[PATCH v2 03/15] hw/riscv: add RISC-V IOMMU base emulation

[Daniel Henrique Barboza]

From: Tomasz Jeznach <tjeznach@rivosinc.com>

The RISC-V IOMMU specification is now ratified as-per the RISC-V
international process. The latest frozen specifcation can be found
at:

https://github.com/riscv-non-isa/riscv-iommu/releases/download/v1.0/riscv-iommu.pdf

Add the foundation of the device emulation for RISC-V IOMMU, which
includes an IOMMU that has no capabilities but MSI interrupt support and
fault queue interfaces. We'll add add more features incrementally in the
next patches.

Co-developed-by: Sebastien Boeuf <seb@rivosinc.com>
Signed-off-by: Sebastien Boeuf <seb@rivosinc.com>
Signed-off-by: Tomasz Jeznach <tjeznach@rivosinc.com>
Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
---
 hw/riscv/Kconfig         |    4 +
 hw/riscv/meson.build     |    1 +
 hw/riscv/riscv-iommu.c   | 1492 ++++++++++++++++++++++++++++++++++++++
 hw/riscv/riscv-iommu.h   |  141 ++++
 hw/riscv/trace-events    |   11 +
 hw/riscv/trace.h         |    2 +
 include/hw/riscv/iommu.h |   36 +
 meson.build              |    1 +
 8 files changed, 1688 insertions(+)
 create mode 100644 hw/riscv/riscv-iommu.c
 create mode 100644 hw/riscv/riscv-iommu.h
 create mode 100644 hw/riscv/trace-events
 create mode 100644 hw/riscv/trace.h
 create mode 100644 include/hw/riscv/iommu.h

diff --git a/hw/riscv/Kconfig b/hw/riscv/Kconfig
index 5d644eb7b1..faf6a10029 100644
--- a/hw/riscv/Kconfig
+++ b/hw/riscv/Kconfig
@@ -1,3 +1,6 @@
+config RISCV_IOMMU
+    bool
+
 config RISCV_NUMA
     bool
 
@@ -38,6 +41,7 @@ config RISCV_VIRT
     select SERIAL
     select RISCV_ACLINT
     select RISCV_APLIC
+    select RISCV_IOMMU
     select RISCV_IMSIC
     select SIFIVE_PLIC
     select SIFIVE_TEST
diff --git a/hw/riscv/meson.build b/hw/riscv/meson.build
index 2f7ee81be3..ba9eebd605 100644
--- a/hw/riscv/meson.build
+++ b/hw/riscv/meson.build
@@ -10,5 +10,6 @@ riscv_ss.add(when: 'CONFIG_SIFIVE_U', if_true: 
files('sifive_u.c'))
 riscv_ss.add(when: 'CONFIG_SPIKE', if_true: files('spike.c'))
 riscv_ss.add(when: 'CONFIG_MICROCHIP_PFSOC', if_true: 
files('microchip_pfsoc.c'))
 riscv_ss.add(when: 'CONFIG_ACPI', if_true: files('virt-acpi-build.c'))
+riscv_ss.add(when: 'CONFIG_RISCV_IOMMU', if_true: files('riscv-iommu.c'))
 
 hw_arch += {'riscv': riscv_ss}
diff --git a/hw/riscv/riscv-iommu.c b/hw/riscv/riscv-iommu.c
new file mode 100644
index 0000000000..df534b99b0
--- /dev/null
+++ b/hw/riscv/riscv-iommu.c
@@ -0,0 +1,1492 @@
+/*
+ * QEMU emulation of an RISC-V IOMMU (Ziommu)
+ *
+ * Copyright (C) 2021-2023, Rivos Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "qemu/osdep.h"
+#include "qom/object.h"
+#include "hw/pci/pci_bus.h"
+#include "hw/pci/pci_device.h"
+#include "hw/qdev-properties.h"
+#include "hw/riscv/riscv_hart.h"
+#include "migration/vmstate.h"
+#include "qapi/error.h"
+#include "qemu/timer.h"
+
+#include "cpu_bits.h"
+#include "riscv-iommu.h"
+#include "riscv-iommu-bits.h"
+#include "trace.h"
+
+#define LIMIT_CACHE_CTX               (1U << 7)
+#define LIMIT_CACHE_IOT               (1U << 20)
+
+/* Physical page number coversions */
+#define PPN_PHYS(ppn)                 ((ppn) << TARGET_PAGE_BITS)
+#define PPN_DOWN(phy)                 ((phy) >> TARGET_PAGE_BITS)
+
+typedef struct RISCVIOMMUContext RISCVIOMMUContext;
+typedef struct RISCVIOMMUEntry RISCVIOMMUEntry;
+
+/* Device assigned I/O address space */
+struct RISCVIOMMUSpace {
+    IOMMUMemoryRegion iova_mr;  /* IOVA memory region for attached device */
+    AddressSpace iova_as;       /* IOVA address space for attached device */
+    RISCVIOMMUState *iommu;     /* Managing IOMMU device state */
+    uint32_t devid;             /* Requester identifier, AKA device_id */
+    bool notifier;              /* IOMMU unmap notifier enabled */
+    QLIST_ENTRY(RISCVIOMMUSpace) list;
+};
+
+/* Device translation context state. */
+struct RISCVIOMMUContext {
+    uint64_t devid:24;          /* Requester Id, AKA device_id */
+    uint64_t pasid:20;          /* Process Address Space ID */
+    uint64_t __rfu:20;          /* reserved */
+    uint64_t tc;                /* Translation Control */
+    uint64_t ta;                /* Translation Attributes */
+    uint64_t msi_addr_mask;     /* MSI filtering - address mask */
+    uint64_t msi_addr_pattern;  /* MSI filtering - address pattern */
+    uint64_t msiptp;            /* MSI redirection page table pointer */
+};
+
+/* IOMMU index for transactions without PASID specified. */
+#define RISCV_IOMMU_NOPASID 0
+
+static void riscv_iommu_notify(RISCVIOMMUState *s, int vec)
+{
+    const uint32_t ipsr =
+        riscv_iommu_reg_mod32(s, RISCV_IOMMU_REG_IPSR, (1 << vec), 0);
+    const uint32_t ivec = riscv_iommu_reg_get32(s, RISCV_IOMMU_REG_IVEC);
+    if (s->notify && !(ipsr & (1 << vec))) {
+        s->notify(s, (ivec >> (vec * 4)) & 0x0F);
+    }
+}
+
+static void riscv_iommu_fault(RISCVIOMMUState *s,
+                              struct riscv_iommu_fq_record *ev)
+{
+    uint32_t ctrl = riscv_iommu_reg_get32(s, RISCV_IOMMU_REG_FQCSR);
+    uint32_t head = riscv_iommu_reg_get32(s, RISCV_IOMMU_REG_FQH) & s->fq_mask;
+    uint32_t tail = riscv_iommu_reg_get32(s, RISCV_IOMMU_REG_FQT) & s->fq_mask;
+    uint32_t next = (tail + 1) & s->fq_mask;
+    uint32_t devid = get_field(ev->hdr, RISCV_IOMMU_FQ_HDR_DID);
+
+    trace_riscv_iommu_flt(s->parent_obj.id, PCI_BUS_NUM(devid), 
PCI_SLOT(devid),
+                          PCI_FUNC(devid), ev->hdr, ev->iotval);
+
+    if (!(ctrl & RISCV_IOMMU_FQCSR_FQON) ||
+        !!(ctrl & (RISCV_IOMMU_FQCSR_FQOF | RISCV_IOMMU_FQCSR_FQMF))) {
+        return;
+    }
+
+    if (head == next) {
+        riscv_iommu_reg_mod32(s, RISCV_IOMMU_REG_FQCSR,
+                              RISCV_IOMMU_FQCSR_FQOF, 0);
+    } else {
+        dma_addr_t addr = s->fq_addr + tail * sizeof(*ev);
+        if (dma_memory_write(s->target_as, addr, ev, sizeof(*ev),
+                             MEMTXATTRS_UNSPECIFIED) != MEMTX_OK) {
+            riscv_iommu_reg_mod32(s, RISCV_IOMMU_REG_FQCSR,
+                                  RISCV_IOMMU_FQCSR_FQMF, 0);
+        } else {
+            riscv_iommu_reg_set32(s, RISCV_IOMMU_REG_FQT, next);
+        }
+    }
+
+    if (ctrl & RISCV_IOMMU_FQCSR_FIE) {
+        riscv_iommu_notify(s, RISCV_IOMMU_INTR_FQ);
+    }
+}
+
+static void riscv_iommu_pri(RISCVIOMMUState *s,
+    struct riscv_iommu_pq_record *pr)
+{
+    uint32_t ctrl = riscv_iommu_reg_get32(s, RISCV_IOMMU_REG_PQCSR);
+    uint32_t head = riscv_iommu_reg_get32(s, RISCV_IOMMU_REG_PQH) & s->pq_mask;
+    uint32_t tail = riscv_iommu_reg_get32(s, RISCV_IOMMU_REG_PQT) & s->pq_mask;
+    uint32_t next = (tail + 1) & s->pq_mask;
+    uint32_t devid = get_field(pr->hdr, RISCV_IOMMU_PREQ_HDR_DID);
+
+    trace_riscv_iommu_pri(s->parent_obj.id, PCI_BUS_NUM(devid), 
PCI_SLOT(devid),
+                          PCI_FUNC(devid), pr->payload);
+
+    if (!(ctrl & RISCV_IOMMU_PQCSR_PQON) ||
+        !!(ctrl & (RISCV_IOMMU_PQCSR_PQOF | RISCV_IOMMU_PQCSR_PQMF))) {
+        return;
+    }
+
+    if (head == next) {
+        riscv_iommu_reg_mod32(s, RISCV_IOMMU_REG_PQCSR,
+                              RISCV_IOMMU_PQCSR_PQOF, 0);
+    } else {
+        dma_addr_t addr = s->pq_addr + tail * sizeof(*pr);
+        if (dma_memory_write(s->target_as, addr, pr, sizeof(*pr),
+                             MEMTXATTRS_UNSPECIFIED) != MEMTX_OK) {
+            riscv_iommu_reg_mod32(s, RISCV_IOMMU_REG_PQCSR,
+                                  RISCV_IOMMU_PQCSR_PQMF, 0);
+        } else {
+            riscv_iommu_reg_set32(s, RISCV_IOMMU_REG_PQT, next);
+        }
+    }
+
+    if (ctrl & RISCV_IOMMU_PQCSR_PIE) {
+        riscv_iommu_notify(s, RISCV_IOMMU_INTR_PQ);
+    }
+}
+
+/* Portable implementation of pext_u64, bit-mask extraction. */
+static uint64_t _pext_u64(uint64_t val, uint64_t ext)
+{
+    uint64_t ret = 0;
+    uint64_t rot = 1;
+
+    while (ext) {
+        if (ext & 1) {
+            if (val & 1) {
+                ret |= rot;
+            }
+            rot <<= 1;
+        }
+        val >>= 1;
+        ext >>= 1;
+    }
+
+    return ret;
+}
+
+/* Check if GPA matches MSI/MRIF pattern. */
+static bool riscv_iommu_msi_check(RISCVIOMMUState *s, RISCVIOMMUContext *ctx,
+    dma_addr_t gpa)
+{
+    if (get_field(ctx->msiptp, RISCV_IOMMU_DC_MSIPTP_MODE) !=
+        RISCV_IOMMU_DC_MSIPTP_MODE_FLAT) {
+        return false; /* Invalid MSI/MRIF mode */
+    }
+
+    if ((PPN_DOWN(gpa) ^ ctx->msi_addr_pattern) & ~ctx->msi_addr_mask) {
+        return false; /* GPA not in MSI range defined by AIA IMSIC rules. */
+    }
+
+    return true;
+}
+
+/* RISCV IOMMU Address Translation Lookup - Page Table Walk */
+static int riscv_iommu_spa_fetch(RISCVIOMMUState *s, RISCVIOMMUContext *ctx,
+    IOMMUTLBEntry *iotlb)
+{
+    /* Early check for MSI address match when IOVA == GPA */
+    if (iotlb->perm & IOMMU_WO &&
+        riscv_iommu_msi_check(s, ctx, iotlb->iova)) {
+        iotlb->target_as = &s->trap_as;
+        iotlb->translated_addr = iotlb->iova;
+        iotlb->addr_mask = ~TARGET_PAGE_MASK;
+        return 0;
+    }
+
+    /* Exit early for pass-through mode. */
+    iotlb->translated_addr = iotlb->iova;
+    iotlb->addr_mask = ~TARGET_PAGE_MASK;
+    /* Allow R/W in pass-through mode */
+    iotlb->perm = IOMMU_RW;
+    return 0;
+}
+
+/* Redirect MSI write for given GPA. */
+static MemTxResult riscv_iommu_msi_write(RISCVIOMMUState *s,
+    RISCVIOMMUContext *ctx, uint64_t gpa, uint64_t data,
+    unsigned size, MemTxAttrs attrs)
+{
+    MemTxResult res;
+    dma_addr_t addr;
+    uint64_t intn;
+    uint32_t n190;
+    uint64_t pte[2];
+
+    if (!riscv_iommu_msi_check(s, ctx, gpa)) {
+        return MEMTX_ACCESS_ERROR;
+    }
+
+    /* Interrupt File Number */
+    intn = _pext_u64(PPN_DOWN(gpa), ctx->msi_addr_mask);
+    if (intn >= 256) {
+        /* Interrupt file number out of range */
+        return MEMTX_ACCESS_ERROR;
+    }
+
+    /* fetch MSI PTE */
+    addr = PPN_PHYS(get_field(ctx->msiptp, RISCV_IOMMU_DC_MSIPTP_PPN));
+    addr = addr | (intn * sizeof(pte));
+    res = dma_memory_read(s->target_as, addr, &pte, sizeof(pte),
+            MEMTXATTRS_UNSPECIFIED);
+    if (res != MEMTX_OK) {
+        return res;
+    }
+
+    le64_to_cpus(&pte[0]);
+    le64_to_cpus(&pte[1]);
+
+    if (!(pte[0] & RISCV_IOMMU_MSI_PTE_V) || (pte[0] & RISCV_IOMMU_MSI_PTE_C)) 
{
+        return MEMTX_ACCESS_ERROR;
+    }
+
+    switch (get_field(pte[0], RISCV_IOMMU_MSI_PTE_M)) {
+    case RISCV_IOMMU_MSI_PTE_M_BASIC:
+        /* MSI Pass-through mode */
+        addr = PPN_PHYS(get_field(pte[0], RISCV_IOMMU_MSI_PTE_PPN));
+        addr = addr | (gpa & TARGET_PAGE_MASK);
+
+        trace_riscv_iommu_msi(s->parent_obj.id, PCI_BUS_NUM(ctx->devid),
+                              PCI_SLOT(ctx->devid), PCI_FUNC(ctx->devid),
+                              gpa, addr);
+
+        return dma_memory_write(s->target_as, addr, &data, size, attrs);
+    case RISCV_IOMMU_MSI_PTE_M_MRIF:
+        /* MRIF mode, continue. */
+        break;
+    default:
+        return MEMTX_ACCESS_ERROR;
+    }
+
+    /*
+     * Report an error for interrupt identities exceeding the maximum allowed
+     * for an IMSIC interrupt file (2047) or destination address is not 32-bit
+     * aligned. See IOMMU Specification, Chapter 2.3. MSI page tables.
+     */
+    if ((data > 2047) || (gpa & 3)) {
+        return MEMTX_ACCESS_ERROR;
+    }
+
+    /* MSI MRIF mode, non atomic pending bit update */
+
+    /* MRIF pending bit address */
+    addr = get_field(pte[0], RISCV_IOMMU_MSI_PTE_MRIF_ADDR) << 9;
+    addr = addr | ((data & 0x7c0) >> 3);
+
+    trace_riscv_iommu_msi(s->parent_obj.id, PCI_BUS_NUM(ctx->devid),
+                          PCI_SLOT(ctx->devid), PCI_FUNC(ctx->devid),
+                          gpa, addr);
+
+    /* MRIF pending bit mask */
+    data = 1ULL << (data & 0x03f);
+    res = dma_memory_read(s->target_as, addr, &intn, sizeof(intn), attrs);
+    if (res != MEMTX_OK) {
+        return res;
+    }
+    intn = intn | data;
+    res = dma_memory_write(s->target_as, addr, &intn, sizeof(intn), attrs);
+    if (res != MEMTX_OK) {
+        return res;
+    }
+
+    /* Get MRIF enable bits */
+    addr = addr + sizeof(intn);
+    res = dma_memory_read(s->target_as, addr, &intn, sizeof(intn), attrs);
+    if (res != MEMTX_OK) {
+        return res;
+    }
+    if (!(intn & data)) {
+        /* notification disabled, MRIF update completed. */
+        return MEMTX_OK;
+    }
+
+    /* Send notification message */
+    addr = PPN_PHYS(get_field(pte[1], RISCV_IOMMU_MSI_MRIF_NPPN));
+    n190 = get_field(pte[1], RISCV_IOMMU_MSI_MRIF_NID) |
+          (get_field(pte[1], RISCV_IOMMU_MSI_MRIF_NID_MSB) << 10);
+
+    res = dma_memory_write(s->target_as, addr, &n190, sizeof(n190), attrs);
+    if (res != MEMTX_OK) {
+        return res;
+    }
+
+    return MEMTX_OK;
+}
+
+/*
+ * RISC-V IOMMU Device Context Loopkup - Device Directory Tree Walk
+ *
+ * @s         : IOMMU Device State
+ * @ctx       : Device Translation Context with devid and pasid set.
+ * @return    : success or fault code.
+ */
+static int riscv_iommu_ctx_fetch(RISCVIOMMUState *s, RISCVIOMMUContext *ctx)
+{
+    const uint64_t ddtp = s->ddtp;
+    unsigned mode = get_field(ddtp, RISCV_IOMMU_DDTP_MODE);
+    dma_addr_t addr = PPN_PHYS(get_field(ddtp, RISCV_IOMMU_DDTP_PPN));
+    struct riscv_iommu_dc dc;
+    /* Device Context format: 0: extended (64 bytes) | 1: base (32 bytes) */
+    const int dc_fmt = !s->enable_msi;
+    const size_t dc_len = sizeof(dc) >> dc_fmt;
+    unsigned depth;
+    uint64_t de;
+
+    switch (mode) {
+    case RISCV_IOMMU_DDTP_MODE_OFF:
+        return RISCV_IOMMU_FQ_CAUSE_DMA_DISABLED;
+
+    case RISCV_IOMMU_DDTP_MODE_BARE:
+        /* mock up pass-through translation context */
+        ctx->tc = RISCV_IOMMU_DC_TC_V;
+        ctx->ta = 0;
+        ctx->msiptp = 0;
+        return 0;
+
+    case RISCV_IOMMU_DDTP_MODE_1LVL:
+        depth = 0;
+        break;
+
+    case RISCV_IOMMU_DDTP_MODE_2LVL:
+        depth = 1;
+        break;
+
+    case RISCV_IOMMU_DDTP_MODE_3LVL:
+        depth = 2;
+        break;
+
+    default:
+        return RISCV_IOMMU_FQ_CAUSE_DDT_MISCONFIGURED;
+    }
+
+    /*
+     * Check supported device id width (in bits).
+     * See IOMMU Specification, Chapter 6. Software guidelines.
+     * - if extended device-context format is used:
+     *   1LVL: 6, 2LVL: 15, 3LVL: 24
+     * - if base device-context format is used:
+     *   1LVL: 7, 2LVL: 16, 3LVL: 24
+     */
+    if (ctx->devid >= (1 << (depth * 9 + 6 + (dc_fmt && depth != 2)))) {
+        return RISCV_IOMMU_FQ_CAUSE_DDT_INVALID;
+    }
+
+    /* Device directory tree walk */
+    for (; depth-- > 0; ) {
+        /*
+         * Select device id index bits based on device directory tree level
+         * and device context format.
+         * See IOMMU Specification, Chapter 2. Data Structures.
+         * - if extended device-context format is used:
+         *   device index: [23:15][14:6][5:0]
+         * - if base device-context format is used:
+         *   device index: [23:16][15:7][6:0]
+         */
+        const int split = depth * 9 + 6 + dc_fmt;
+        addr |= ((ctx->devid >> split) << 3) & ~TARGET_PAGE_MASK;
+        if (dma_memory_read(s->target_as, addr, &de, sizeof(de),
+                            MEMTXATTRS_UNSPECIFIED) != MEMTX_OK) {
+            return RISCV_IOMMU_FQ_CAUSE_DDT_LOAD_FAULT;
+        }
+        le64_to_cpus(&de);
+        if (!(de & RISCV_IOMMU_DDTE_VALID)) {
+            /* invalid directory entry */
+            return RISCV_IOMMU_FQ_CAUSE_DDT_INVALID;
+        }
+        if (de & ~(RISCV_IOMMU_DDTE_PPN | RISCV_IOMMU_DDTE_VALID)) {
+            /* reserved bits set */
+            return RISCV_IOMMU_FQ_CAUSE_DDT_INVALID;
+        }
+        addr = PPN_PHYS(get_field(de, RISCV_IOMMU_DDTE_PPN));
+    }
+
+    /* index into device context entry page */
+    addr |= (ctx->devid * dc_len) & ~TARGET_PAGE_MASK;
+
+    memset(&dc, 0, sizeof(dc));
+    if (dma_memory_read(s->target_as, addr, &dc, dc_len,
+                        MEMTXATTRS_UNSPECIFIED) != MEMTX_OK) {
+        return RISCV_IOMMU_FQ_CAUSE_DDT_LOAD_FAULT;
+    }
+
+    /* Set translation context. */
+    ctx->tc = le64_to_cpu(dc.tc);
+    ctx->ta = le64_to_cpu(dc.ta);
+    ctx->msiptp = le64_to_cpu(dc.msiptp);
+    ctx->msi_addr_mask = le64_to_cpu(dc.msi_addr_mask);
+    ctx->msi_addr_pattern = le64_to_cpu(dc.msi_addr_pattern);
+
+    if (!(ctx->tc & RISCV_IOMMU_DC_TC_V)) {
+        return RISCV_IOMMU_FQ_CAUSE_DDT_INVALID;
+    }
+
+    if (!(ctx->tc & RISCV_IOMMU_DC_TC_PDTV)) {
+        if (ctx->pasid != RISCV_IOMMU_NOPASID) {
+            /* PASID is disabled */
+            return RISCV_IOMMU_FQ_CAUSE_TTYPE_BLOCKED;
+        }
+        return 0;
+    }
+
+    /* FSC.TC.PDTV enabled */
+    if (mode > RISCV_IOMMU_DC_FSC_PDTP_MODE_PD20) {
+        /* Invalid PDTP.MODE */
+        return RISCV_IOMMU_FQ_CAUSE_PDT_MISCONFIGURED;
+    }
+
+    for (depth = mode - RISCV_IOMMU_DC_FSC_PDTP_MODE_PD8; depth-- > 0; ) {
+        /*
+         * Select process id index bits based on process directory tree
+         * level. See IOMMU Specification, 2.2. Process-Directory-Table.
+         */
+        const int split = depth * 9 + 8;
+        addr |= ((ctx->pasid >> split) << 3) & ~TARGET_PAGE_MASK;
+        if (dma_memory_read(s->target_as, addr, &de, sizeof(de),
+                            MEMTXATTRS_UNSPECIFIED) != MEMTX_OK) {
+            return RISCV_IOMMU_FQ_CAUSE_PDT_LOAD_FAULT;
+        }
+        le64_to_cpus(&de);
+        if (!(de & RISCV_IOMMU_PC_TA_V)) {
+            return RISCV_IOMMU_FQ_CAUSE_PDT_INVALID;
+        }
+        addr = PPN_PHYS(get_field(de, RISCV_IOMMU_PC_FSC_PPN));
+    }
+
+    /* Leaf entry in PDT */
+    addr |= (ctx->pasid << 4) & ~TARGET_PAGE_MASK;
+    if (dma_memory_read(s->target_as, addr, &dc.ta, sizeof(uint64_t) * 2,
+                        MEMTXATTRS_UNSPECIFIED) != MEMTX_OK) {
+        return RISCV_IOMMU_FQ_CAUSE_PDT_LOAD_FAULT;
+    }
+
+    /* Use FSC and TA from process directory entry. */
+    ctx->ta = le64_to_cpu(dc.ta);
+
+    return 0;
+}
+
+/* Translation Context cache support */
+static gboolean __ctx_equal(gconstpointer v1, gconstpointer v2)
+{
+    RISCVIOMMUContext *c1 = (RISCVIOMMUContext *) v1;
+    RISCVIOMMUContext *c2 = (RISCVIOMMUContext *) v2;
+    return c1->devid == c2->devid && c1->pasid == c2->pasid;
+}
+
+static guint __ctx_hash(gconstpointer v)
+{
+    RISCVIOMMUContext *ctx = (RISCVIOMMUContext *) v;
+    /* Generate simple hash of (pasid, devid), assuming 24-bit wide devid */
+    return (guint)(ctx->devid) + ((guint)(ctx->pasid) << 24);
+}
+
+static void __ctx_inval_devid_pasid(gpointer key, gpointer value, gpointer 
data)
+{
+    RISCVIOMMUContext *ctx = (RISCVIOMMUContext *) value;
+    RISCVIOMMUContext *arg = (RISCVIOMMUContext *) data;
+    if (ctx->tc & RISCV_IOMMU_DC_TC_V &&
+        ctx->devid == arg->devid &&
+        ctx->pasid == arg->pasid) {
+        ctx->tc &= ~RISCV_IOMMU_DC_TC_V;
+    }
+}
+
+static void __ctx_inval_devid(gpointer key, gpointer value, gpointer data)
+{
+    RISCVIOMMUContext *ctx = (RISCVIOMMUContext *) value;
+    RISCVIOMMUContext *arg = (RISCVIOMMUContext *) data;
+    if (ctx->tc & RISCV_IOMMU_DC_TC_V &&
+        ctx->devid == arg->devid) {
+        ctx->tc &= ~RISCV_IOMMU_DC_TC_V;
+    }
+}
+
+static void __ctx_inval_all(gpointer key, gpointer value, gpointer data)
+{
+    RISCVIOMMUContext *ctx = (RISCVIOMMUContext *) value;
+    if (ctx->tc & RISCV_IOMMU_DC_TC_V) {
+        ctx->tc &= ~RISCV_IOMMU_DC_TC_V;
+    }
+}
+
+static void riscv_iommu_ctx_inval(RISCVIOMMUState *s, GHFunc func,
+    uint32_t devid, uint32_t pasid)
+{
+    GHashTable *ctx_cache;
+    RISCVIOMMUContext key = {
+        .devid = devid,
+        .pasid = pasid,
+    };
+    ctx_cache = g_hash_table_ref(s->ctx_cache);
+    g_hash_table_foreach(ctx_cache, func, &key);
+    g_hash_table_unref(ctx_cache);
+}
+
+/* Find or allocate translation context for a given {device_id, process_id} */
+static RISCVIOMMUContext *riscv_iommu_ctx(RISCVIOMMUState *s,
+    unsigned devid, unsigned pasid, void **ref)
+{
+    GHashTable *ctx_cache;
+    RISCVIOMMUContext *ctx;
+    RISCVIOMMUContext key = {
+        .devid = devid,
+        .pasid = pasid,
+    };
+
+    ctx_cache = g_hash_table_ref(s->ctx_cache);
+    ctx = g_hash_table_lookup(ctx_cache, &key);
+
+    if (ctx && (ctx->tc & RISCV_IOMMU_DC_TC_V)) {
+        *ref = ctx_cache;
+        return ctx;
+    }
+
+    if (g_hash_table_size(s->ctx_cache) >= LIMIT_CACHE_CTX) {
+        ctx_cache = g_hash_table_new_full(__ctx_hash, __ctx_equal,
+                                          g_free, NULL);
+        g_hash_table_unref(qatomic_xchg(&s->ctx_cache, ctx_cache));
+    }
+
+    ctx = g_new0(RISCVIOMMUContext, 1);
+    ctx->devid = devid;
+    ctx->pasid = pasid;
+
+    int fault = riscv_iommu_ctx_fetch(s, ctx);
+    if (!fault) {
+        g_hash_table_add(ctx_cache, ctx);
+        *ref = ctx_cache;
+        return ctx;
+    }
+
+    g_hash_table_unref(ctx_cache);
+    *ref = NULL;
+
+    if (!(ctx->tc & RISCV_IOMMU_DC_TC_DTF)) {
+        struct riscv_iommu_fq_record ev = { 0 };
+        ev.hdr = set_field(ev.hdr, RISCV_IOMMU_FQ_HDR_CAUSE, fault);
+        ev.hdr = set_field(ev.hdr, RISCV_IOMMU_FQ_HDR_TTYPE,
+            RISCV_IOMMU_FQ_TTYPE_UADDR_RD);
+        ev.hdr = set_field(ev.hdr, RISCV_IOMMU_FQ_HDR_DID, devid);
+        ev.hdr = set_field(ev.hdr, RISCV_IOMMU_FQ_HDR_PID, pasid);
+        ev.hdr = set_field(ev.hdr, RISCV_IOMMU_FQ_HDR_PV, !!pasid);
+        riscv_iommu_fault(s, &ev);
+    }
+
+    g_free(ctx);
+    return NULL;
+}
+
+static void riscv_iommu_ctx_put(RISCVIOMMUState *s, void *ref)
+{
+    if (ref) {
+        g_hash_table_unref((GHashTable *)ref);
+    }
+}
+
+/* Find or allocate address space for a given device */
+static AddressSpace *riscv_iommu_space(RISCVIOMMUState *s, uint32_t devid)
+{
+    RISCVIOMMUSpace *as;
+
+    /* FIXME: PCIe bus remapping for attached endpoints. */
+    devid |= s->bus << 8;
+
+    qemu_mutex_lock(&s->core_lock);
+    QLIST_FOREACH(as, &s->spaces, list) {
+        if (as->devid == devid) {
+            break;
+        }
+    }
+    qemu_mutex_unlock(&s->core_lock);
+
+    if (as == NULL) {
+        char name[64];
+        as = g_new0(RISCVIOMMUSpace, 1);
+
+        as->iommu = s;
+        as->devid = devid;
+
+        snprintf(name, sizeof(name), "riscv-iommu-%04x:%02x.%d-iova",
+            PCI_BUS_NUM(as->devid), PCI_SLOT(as->devid), PCI_FUNC(as->devid));
+
+        /* IOVA address space, untranslated addresses */
+        memory_region_init_iommu(&as->iova_mr, sizeof(as->iova_mr),
+            TYPE_RISCV_IOMMU_MEMORY_REGION,
+            OBJECT(as), name, UINT64_MAX);
+        address_space_init(&as->iova_as, MEMORY_REGION(&as->iova_mr),
+            TYPE_RISCV_IOMMU_PCI);
+
+        qemu_mutex_lock(&s->core_lock);
+        QLIST_INSERT_HEAD(&s->spaces, as, list);
+        qemu_mutex_unlock(&s->core_lock);
+
+        trace_riscv_iommu_new(s->parent_obj.id, PCI_BUS_NUM(as->devid),
+                PCI_SLOT(as->devid), PCI_FUNC(as->devid));
+    }
+    return &as->iova_as;
+}
+
+static int riscv_iommu_translate(RISCVIOMMUState *s, RISCVIOMMUContext *ctx,
+    IOMMUTLBEntry *iotlb)
+{
+    bool enable_faults;
+    bool enable_pasid;
+    bool enable_pri;
+    int fault;
+
+    enable_faults = !(ctx->tc & RISCV_IOMMU_DC_TC_DTF);
+    /*
+     * TC[32] is reserved for custom extensions, used here to temporarily
+     * enable automatic page-request generation for ATS queries.
+     */
+    enable_pri = (iotlb->perm == IOMMU_NONE) && (ctx->tc & BIT_ULL(32));
+    enable_pasid = (ctx->tc & RISCV_IOMMU_DC_TC_PDTV);
+
+    /* Translate using device directory / page table information. */
+    fault = riscv_iommu_spa_fetch(s, ctx, iotlb);
+
+    if (enable_pri && fault) {
+        struct riscv_iommu_pq_record pr = {0};
+        if (enable_pasid) {
+            pr.hdr = set_field(RISCV_IOMMU_PREQ_HDR_PV,
+                RISCV_IOMMU_PREQ_HDR_PID, ctx->pasid);
+        }
+        pr.hdr = set_field(pr.hdr, RISCV_IOMMU_PREQ_HDR_DID, ctx->devid);
+        pr.payload = (iotlb->iova & TARGET_PAGE_MASK) |
+                     RISCV_IOMMU_PREQ_PAYLOAD_M;
+        riscv_iommu_pri(s, &pr);
+        return fault;
+    }
+
+    if (enable_faults && fault) {
+        struct riscv_iommu_fq_record ev;
+        unsigned ttype;
+
+        if (iotlb->perm & IOMMU_RW) {
+            ttype = RISCV_IOMMU_FQ_TTYPE_UADDR_WR;
+        } else {
+            ttype = RISCV_IOMMU_FQ_TTYPE_UADDR_RD;
+        }
+        ev.hdr = set_field(0, RISCV_IOMMU_FQ_HDR_CAUSE, fault);
+        ev.hdr = set_field(ev.hdr, RISCV_IOMMU_FQ_HDR_TTYPE, ttype);
+        ev.hdr = set_field(ev.hdr, RISCV_IOMMU_FQ_HDR_PV, enable_pasid);
+        ev.hdr = set_field(ev.hdr, RISCV_IOMMU_FQ_HDR_PID, ctx->pasid);
+        ev.hdr = set_field(ev.hdr, RISCV_IOMMU_FQ_HDR_DID, ctx->devid);
+        ev.iotval    = iotlb->iova;
+        ev.iotval2   = iotlb->translated_addr;
+        ev._reserved = 0;
+        riscv_iommu_fault(s, &ev);
+        return fault;
+    }
+
+    return 0;
+}
+
+/* IOMMU Command Interface */
+static MemTxResult riscv_iommu_iofence(RISCVIOMMUState *s, bool notify,
+    uint64_t addr, uint32_t data)
+{
+    /*
+     * ATS processing in this implementation of the IOMMU is synchronous,
+     * no need to wait for completions here.
+     */
+    if (!notify) {
+        return MEMTX_OK;
+    }
+
+    return dma_memory_write(s->target_as, addr, &data, sizeof(data),
+        MEMTXATTRS_UNSPECIFIED);
+}
+
+static void riscv_iommu_process_ddtp(RISCVIOMMUState *s)
+{
+    uint64_t old_ddtp = s->ddtp;
+    uint64_t new_ddtp = riscv_iommu_reg_get64(s, RISCV_IOMMU_REG_DDTP);
+    unsigned new_mode = get_field(new_ddtp, RISCV_IOMMU_DDTP_MODE);
+    unsigned old_mode = get_field(old_ddtp, RISCV_IOMMU_DDTP_MODE);
+    bool ok = false;
+
+    /*
+     * Check for allowed DDTP.MODE transitions:
+     * {OFF, BARE}        -> {OFF, BARE, 1LVL, 2LVL, 3LVL}
+     * {1LVL, 2LVL, 3LVL} -> {OFF, BARE}
+     */
+    if (new_mode == old_mode ||
+        new_mode == RISCV_IOMMU_DDTP_MODE_OFF ||
+        new_mode == RISCV_IOMMU_DDTP_MODE_BARE) {
+        ok = true;
+    } else if (new_mode == RISCV_IOMMU_DDTP_MODE_1LVL ||
+               new_mode == RISCV_IOMMU_DDTP_MODE_2LVL ||
+               new_mode == RISCV_IOMMU_DDTP_MODE_3LVL) {
+        ok = old_mode == RISCV_IOMMU_DDTP_MODE_OFF ||
+             old_mode == RISCV_IOMMU_DDTP_MODE_BARE;
+    }
+
+    if (ok) {
+        /* clear reserved and busy bits, report back sanitized version */
+        new_ddtp = set_field(new_ddtp & RISCV_IOMMU_DDTP_PPN,
+                             RISCV_IOMMU_DDTP_MODE, new_mode);
+    } else {
+        new_ddtp = old_ddtp;
+    }
+    s->ddtp = new_ddtp;
+
+    riscv_iommu_reg_set64(s, RISCV_IOMMU_REG_DDTP, new_ddtp);
+}
+
+/* Command function and opcode field. */
+#define RISCV_IOMMU_CMD(func, op) (((func) << 7) | (op))
+
+static void riscv_iommu_process_cq_tail(RISCVIOMMUState *s)
+{
+    struct riscv_iommu_command cmd;
+    MemTxResult res;
+    dma_addr_t addr;
+    uint32_t tail, head, ctrl;
+    uint64_t cmd_opcode;
+    GHFunc func;
+
+    ctrl = riscv_iommu_reg_get32(s, RISCV_IOMMU_REG_CQCSR);
+    tail = riscv_iommu_reg_get32(s, RISCV_IOMMU_REG_CQT) & s->cq_mask;
+    head = riscv_iommu_reg_get32(s, RISCV_IOMMU_REG_CQH) & s->cq_mask;
+
+    /* Check for pending error or queue processing disabled */
+    if (!(ctrl & RISCV_IOMMU_CQCSR_CQON) ||
+        !!(ctrl & (RISCV_IOMMU_CQCSR_CMD_ILL | RISCV_IOMMU_CQCSR_CQMF))) {
+        return;
+    }
+
+    while (tail != head) {
+        addr = s->cq_addr  + head * sizeof(cmd);
+        res = dma_memory_read(s->target_as, addr, &cmd, sizeof(cmd),
+                              MEMTXATTRS_UNSPECIFIED);
+
+        if (res != MEMTX_OK) {
+            riscv_iommu_reg_mod32(s, RISCV_IOMMU_REG_CQCSR,
+                                  RISCV_IOMMU_CQCSR_CQMF, 0);
+            goto fault;
+        }
+
+        trace_riscv_iommu_cmd(s->parent_obj.id, cmd.dword0, cmd.dword1);
+
+        cmd_opcode = get_field(cmd.dword0,
+                               RISCV_IOMMU_CMD_OPCODE | RISCV_IOMMU_CMD_FUNC);
+
+        switch (cmd_opcode) {
+        case RISCV_IOMMU_CMD(RISCV_IOMMU_CMD_IOFENCE_FUNC_C,
+                             RISCV_IOMMU_CMD_IOFENCE_OPCODE):
+            res = riscv_iommu_iofence(s,
+                cmd.dword0 & RISCV_IOMMU_CMD_IOFENCE_AV, cmd.dword1,
+                get_field(cmd.dword0, RISCV_IOMMU_CMD_IOFENCE_DATA));
+
+            if (res != MEMTX_OK) {
+                riscv_iommu_reg_mod32(s, RISCV_IOMMU_REG_CQCSR,
+                                      RISCV_IOMMU_CQCSR_CQMF, 0);
+                goto fault;
+            }
+            break;
+
+        case RISCV_IOMMU_CMD(RISCV_IOMMU_CMD_IOTINVAL_FUNC_GVMA,
+                             RISCV_IOMMU_CMD_IOTINVAL_OPCODE):
+            if (cmd.dword0 & RISCV_IOMMU_CMD_IOTINVAL_PSCV) {
+                /* illegal command arguments IOTINVAL.GVMA & PSCV == 1 */
+                goto cmd_ill;
+            }
+            /* translation cache not implemented yet */
+            break;
+
+        case RISCV_IOMMU_CMD(RISCV_IOMMU_CMD_IOTINVAL_FUNC_VMA,
+                             RISCV_IOMMU_CMD_IOTINVAL_OPCODE):
+            /* translation cache not implemented yet */
+            break;
+
+        case RISCV_IOMMU_CMD(RISCV_IOMMU_CMD_IODIR_FUNC_INVAL_DDT,
+                             RISCV_IOMMU_CMD_IODIR_OPCODE):
+            if (!(cmd.dword0 & RISCV_IOMMU_CMD_IODIR_DV)) {
+                /* invalidate all device context cache mappings */
+                func = __ctx_inval_all;
+            } else {
+                /* invalidate all device context matching DID */
+                func = __ctx_inval_devid;
+            }
+            riscv_iommu_ctx_inval(s, func,
+                get_field(cmd.dword0, RISCV_IOMMU_CMD_IODIR_DID), 0);
+            break;
+
+        case RISCV_IOMMU_CMD(RISCV_IOMMU_CMD_IODIR_FUNC_INVAL_PDT,
+                             RISCV_IOMMU_CMD_IODIR_OPCODE):
+            if (!(cmd.dword0 & RISCV_IOMMU_CMD_IODIR_DV)) {
+                /* illegal command arguments IODIR_PDT & DV == 0 */
+                goto cmd_ill;
+            } else {
+                func = __ctx_inval_devid_pasid;
+            }
+            riscv_iommu_ctx_inval(s, func,
+                get_field(cmd.dword0, RISCV_IOMMU_CMD_IODIR_DID),
+                get_field(cmd.dword0, RISCV_IOMMU_CMD_IODIR_PID));
+            break;
+
+        default:
+        cmd_ill:
+            /* Invalid instruction, do not advance instruction index. */
+            riscv_iommu_reg_mod32(s, RISCV_IOMMU_REG_CQCSR,
+                RISCV_IOMMU_CQCSR_CMD_ILL, 0);
+            goto fault;
+        }
+
+        /* Advance and update head pointer after command completes. */
+        head = (head + 1) & s->cq_mask;
+        riscv_iommu_reg_set32(s, RISCV_IOMMU_REG_CQH, head);
+    }
+    return;
+
+fault:
+    if (ctrl & RISCV_IOMMU_CQCSR_CIE) {
+        riscv_iommu_notify(s, RISCV_IOMMU_INTR_CQ);
+    }
+}
+
+static void riscv_iommu_process_cq_control(RISCVIOMMUState *s)
+{
+    uint64_t base;
+    uint32_t ctrl_set = riscv_iommu_reg_get32(s, RISCV_IOMMU_REG_CQCSR);
+    uint32_t ctrl_clr;
+    bool enable = !!(ctrl_set & RISCV_IOMMU_CQCSR_CQEN);
+    bool active = !!(ctrl_set & RISCV_IOMMU_CQCSR_CQON);
+
+    if (enable && !active) {
+        base = riscv_iommu_reg_get64(s, RISCV_IOMMU_REG_CQB);
+        s->cq_mask = (2ULL << get_field(base, RISCV_IOMMU_CQB_LOG2SZ)) - 1;
+        s->cq_addr = PPN_PHYS(get_field(base, RISCV_IOMMU_CQB_PPN));
+        stl_le_p(&s->regs_ro[RISCV_IOMMU_REG_CQT], ~s->cq_mask);
+        stl_le_p(&s->regs_rw[RISCV_IOMMU_REG_CQH], 0);
+        stl_le_p(&s->regs_rw[RISCV_IOMMU_REG_CQT], 0);
+        ctrl_set = RISCV_IOMMU_CQCSR_CQON;
+        ctrl_clr = RISCV_IOMMU_CQCSR_BUSY | RISCV_IOMMU_CQCSR_CQMF |
+            RISCV_IOMMU_CQCSR_CMD_ILL | RISCV_IOMMU_CQCSR_CMD_TO;
+    } else if (!enable && active) {
+        stl_le_p(&s->regs_ro[RISCV_IOMMU_REG_CQT], ~0);
+        ctrl_set = 0;
+        ctrl_clr = RISCV_IOMMU_CQCSR_BUSY | RISCV_IOMMU_CQCSR_CQON;
+    } else {
+        ctrl_set = 0;
+        ctrl_clr = RISCV_IOMMU_CQCSR_BUSY;
+    }
+
+    riscv_iommu_reg_mod32(s, RISCV_IOMMU_REG_CQCSR, ctrl_set, ctrl_clr);
+}
+
+static void riscv_iommu_process_fq_control(RISCVIOMMUState *s)
+{
+    uint64_t base;
+    uint32_t ctrl_set = riscv_iommu_reg_get32(s, RISCV_IOMMU_REG_FQCSR);
+    uint32_t ctrl_clr;
+    bool enable = !!(ctrl_set & RISCV_IOMMU_FQCSR_FQEN);
+    bool active = !!(ctrl_set & RISCV_IOMMU_FQCSR_FQON);
+
+    if (enable && !active) {
+        base = riscv_iommu_reg_get64(s, RISCV_IOMMU_REG_FQB);
+        s->fq_mask = (2ULL << get_field(base, RISCV_IOMMU_FQB_LOG2SZ)) - 1;
+        s->fq_addr = PPN_PHYS(get_field(base, RISCV_IOMMU_FQB_PPN));
+        stl_le_p(&s->regs_ro[RISCV_IOMMU_REG_FQH], ~s->fq_mask);
+        stl_le_p(&s->regs_rw[RISCV_IOMMU_REG_FQH], 0);
+        stl_le_p(&s->regs_rw[RISCV_IOMMU_REG_FQT], 0);
+        ctrl_set = RISCV_IOMMU_FQCSR_FQON;
+        ctrl_clr = RISCV_IOMMU_FQCSR_BUSY | RISCV_IOMMU_FQCSR_FQMF |
+            RISCV_IOMMU_FQCSR_FQOF;
+    } else if (!enable && active) {
+        stl_le_p(&s->regs_ro[RISCV_IOMMU_REG_FQH], ~0);
+        ctrl_set = 0;
+        ctrl_clr = RISCV_IOMMU_FQCSR_BUSY | RISCV_IOMMU_FQCSR_FQON;
+    } else {
+        ctrl_set = 0;
+        ctrl_clr = RISCV_IOMMU_FQCSR_BUSY;
+    }
+
+    riscv_iommu_reg_mod32(s, RISCV_IOMMU_REG_FQCSR, ctrl_set, ctrl_clr);
+}
+
+static void riscv_iommu_process_pq_control(RISCVIOMMUState *s)
+{
+    uint64_t base;
+    uint32_t ctrl_set = riscv_iommu_reg_get32(s, RISCV_IOMMU_REG_PQCSR);
+    uint32_t ctrl_clr;
+    bool enable = !!(ctrl_set & RISCV_IOMMU_PQCSR_PQEN);
+    bool active = !!(ctrl_set & RISCV_IOMMU_PQCSR_PQON);
+
+    if (enable && !active) {
+        base = riscv_iommu_reg_get64(s, RISCV_IOMMU_REG_PQB);
+        s->pq_mask = (2ULL << get_field(base, RISCV_IOMMU_PQB_LOG2SZ)) - 1;
+        s->pq_addr = PPN_PHYS(get_field(base, RISCV_IOMMU_PQB_PPN));
+        stl_le_p(&s->regs_ro[RISCV_IOMMU_REG_PQH], ~s->pq_mask);
+        stl_le_p(&s->regs_rw[RISCV_IOMMU_REG_PQH], 0);
+        stl_le_p(&s->regs_rw[RISCV_IOMMU_REG_PQT], 0);
+        ctrl_set = RISCV_IOMMU_PQCSR_PQON;
+        ctrl_clr = RISCV_IOMMU_PQCSR_BUSY | RISCV_IOMMU_PQCSR_PQMF |
+            RISCV_IOMMU_PQCSR_PQOF;
+    } else if (!enable && active) {
+        stl_le_p(&s->regs_ro[RISCV_IOMMU_REG_PQH], ~0);
+        ctrl_set = 0;
+        ctrl_clr = RISCV_IOMMU_PQCSR_BUSY | RISCV_IOMMU_PQCSR_PQON;
+    } else {
+        ctrl_set = 0;
+        ctrl_clr = RISCV_IOMMU_PQCSR_BUSY;
+    }
+
+    riscv_iommu_reg_mod32(s, RISCV_IOMMU_REG_PQCSR, ctrl_set, ctrl_clr);
+}
+
+/* Core IOMMU execution activation */
+enum {
+    RISCV_IOMMU_EXEC_DDTP,
+    RISCV_IOMMU_EXEC_CQCSR,
+    RISCV_IOMMU_EXEC_CQT,
+    RISCV_IOMMU_EXEC_FQCSR,
+    RISCV_IOMMU_EXEC_FQH,
+    RISCV_IOMMU_EXEC_PQCSR,
+    RISCV_IOMMU_EXEC_PQH,
+    RISCV_IOMMU_EXEC_TR_REQUEST,
+    /* RISCV_IOMMU_EXEC_EXIT must be the last enum value */
+    RISCV_IOMMU_EXEC_EXIT,
+};
+
+static void *riscv_iommu_core_proc(void* arg)
+{
+    RISCVIOMMUState *s = arg;
+    unsigned exec = 0;
+    unsigned mask = 0;
+
+    while (!(exec & BIT(RISCV_IOMMU_EXEC_EXIT))) {
+        mask = (mask ? mask : BIT(RISCV_IOMMU_EXEC_EXIT)) >> 1;
+        switch (exec & mask) {
+        case BIT(RISCV_IOMMU_EXEC_DDTP):
+            riscv_iommu_process_ddtp(s);
+            break;
+        case BIT(RISCV_IOMMU_EXEC_CQCSR):
+            riscv_iommu_process_cq_control(s);
+            break;
+        case BIT(RISCV_IOMMU_EXEC_CQT):
+            riscv_iommu_process_cq_tail(s);
+            break;
+        case BIT(RISCV_IOMMU_EXEC_FQCSR):
+            riscv_iommu_process_fq_control(s);
+            break;
+        case BIT(RISCV_IOMMU_EXEC_FQH):
+            /* NOP */
+            break;
+        case BIT(RISCV_IOMMU_EXEC_PQCSR):
+            riscv_iommu_process_pq_control(s);
+            break;
+        case BIT(RISCV_IOMMU_EXEC_PQH):
+            /* NOP */
+            break;
+        case BIT(RISCV_IOMMU_EXEC_TR_REQUEST):
+            /* DBG support not implemented yet */
+            break;
+        }
+        exec &= ~mask;
+        if (!exec) {
+            qemu_mutex_lock(&s->core_lock);
+            exec = s->core_exec;
+            while (!exec) {
+                qemu_cond_wait(&s->core_cond, &s->core_lock);
+                exec = s->core_exec;
+            }
+            s->core_exec = 0;
+            qemu_mutex_unlock(&s->core_lock);
+        }
+    };
+
+    return NULL;
+}
+
+static MemTxResult riscv_iommu_mmio_write(void *opaque, hwaddr addr,
+    uint64_t data, unsigned size, MemTxAttrs attrs)
+{
+    RISCVIOMMUState *s = opaque;
+    uint32_t regb = addr & ~3;
+    uint32_t busy = 0;
+    uint32_t exec = 0;
+
+    if (size == 0 || size > 8 || (addr & (size - 1)) != 0) {
+        /* Unsupported MMIO alignment or access size */
+        return MEMTX_ERROR;
+    }
+
+    if (addr + size > RISCV_IOMMU_REG_MSI_CONFIG) {
+        /* Unsupported MMIO access location. */
+        return MEMTX_ACCESS_ERROR;
+    }
+
+    /* Track actionable MMIO write. */
+    switch (regb) {
+    case RISCV_IOMMU_REG_DDTP:
+    case RISCV_IOMMU_REG_DDTP + 4:
+        exec = BIT(RISCV_IOMMU_EXEC_DDTP);
+        regb = RISCV_IOMMU_REG_DDTP;
+        busy = RISCV_IOMMU_DDTP_BUSY;
+        break;
+
+    case RISCV_IOMMU_REG_CQT:
+        exec = BIT(RISCV_IOMMU_EXEC_CQT);
+        break;
+
+    case RISCV_IOMMU_REG_CQCSR:
+        exec = BIT(RISCV_IOMMU_EXEC_CQCSR);
+        busy = RISCV_IOMMU_CQCSR_BUSY;
+        break;
+
+    case RISCV_IOMMU_REG_FQH:
+        exec = BIT(RISCV_IOMMU_EXEC_FQH);
+        break;
+
+    case RISCV_IOMMU_REG_FQCSR:
+        exec = BIT(RISCV_IOMMU_EXEC_FQCSR);
+        busy = RISCV_IOMMU_FQCSR_BUSY;
+        break;
+
+    case RISCV_IOMMU_REG_PQH:
+        exec = BIT(RISCV_IOMMU_EXEC_PQH);
+        break;
+
+    case RISCV_IOMMU_REG_PQCSR:
+        exec = BIT(RISCV_IOMMU_EXEC_PQCSR);
+        busy = RISCV_IOMMU_PQCSR_BUSY;
+        break;
+    }
+
+    /*
+     * Registers update might be not synchronized with core logic.
+     * If system software updates register when relevant BUSY bit is set
+     * IOMMU behavior of additional writes to the register is UNSPECIFIED
+     */
+
+    qemu_spin_lock(&s->regs_lock);
+    if (size == 1) {
+        uint8_t ro = s->regs_ro[addr];
+        uint8_t wc = s->regs_wc[addr];
+        uint8_t rw = s->regs_rw[addr];
+        s->regs_rw[addr] = ((rw & ro) | (data & ~ro)) & ~(data & wc);
+    } else if (size == 2) {
+        uint16_t ro = lduw_le_p(&s->regs_ro[addr]);
+        uint16_t wc = lduw_le_p(&s->regs_wc[addr]);
+        uint16_t rw = lduw_le_p(&s->regs_rw[addr]);
+        stw_le_p(&s->regs_rw[addr], ((rw & ro) | (data & ~ro)) & ~(data & wc));
+    } else if (size == 4) {
+        uint32_t ro = ldl_le_p(&s->regs_ro[addr]);
+        uint32_t wc = ldl_le_p(&s->regs_wc[addr]);
+        uint32_t rw = ldl_le_p(&s->regs_rw[addr]);
+        stl_le_p(&s->regs_rw[addr], ((rw & ro) | (data & ~ro)) & ~(data & wc));
+    } else if (size == 8) {
+        uint64_t ro = ldq_le_p(&s->regs_ro[addr]);
+        uint64_t wc = ldq_le_p(&s->regs_wc[addr]);
+        uint64_t rw = ldq_le_p(&s->regs_rw[addr]);
+        stq_le_p(&s->regs_rw[addr], ((rw & ro) | (data & ~ro)) & ~(data & wc));
+    }
+
+    /* Busy flag update, MSB 4-byte register. */
+    if (busy) {
+        uint32_t rw = ldl_le_p(&s->regs_rw[regb]);
+        stl_le_p(&s->regs_rw[regb], rw | busy);
+    }
+    qemu_spin_unlock(&s->regs_lock);
+
+    /* Wake up core processing thread. */
+    if (exec) {
+        qemu_mutex_lock(&s->core_lock);
+        s->core_exec |= exec;
+        qemu_cond_signal(&s->core_cond);
+        qemu_mutex_unlock(&s->core_lock);
+    }
+
+    return MEMTX_OK;
+}
+
+static MemTxResult riscv_iommu_mmio_read(void *opaque, hwaddr addr,
+    uint64_t *data, unsigned size, MemTxAttrs attrs)
+{
+    RISCVIOMMUState *s = opaque;
+    uint64_t val = -1;
+    uint8_t *ptr;
+
+    if ((addr & (size - 1)) != 0) {
+        /* Unsupported MMIO alignment. */
+        return MEMTX_ERROR;
+    }
+
+    if (addr + size > RISCV_IOMMU_REG_MSI_CONFIG) {
+        return MEMTX_ACCESS_ERROR;
+    }
+
+    ptr = &s->regs_rw[addr];
+
+    if (size == 1) {
+        val = (uint64_t)*ptr;
+    } else if (size == 2) {
+        val = lduw_le_p(ptr);
+    } else if (size == 4) {
+        val = ldl_le_p(ptr);
+    } else if (size == 8) {
+        val = ldq_le_p(ptr);
+    } else {
+        return MEMTX_ERROR;
+    }
+
+    *data = val;
+
+    return MEMTX_OK;
+}
+
+static const MemoryRegionOps riscv_iommu_mmio_ops = {
+    .read_with_attrs = riscv_iommu_mmio_read,
+    .write_with_attrs = riscv_iommu_mmio_write,
+    .endianness = DEVICE_NATIVE_ENDIAN,
+    .impl = {
+        .min_access_size = 1,
+        .max_access_size = 8,
+        .unaligned = false,
+    },
+    .valid = {
+        .min_access_size = 1,
+        .max_access_size = 8,
+    }
+};
+
+/*
+ * Translations matching MSI pattern check are redirected to "riscv-iommu-trap"
+ * memory region as untranslated address, for additional MSI/MRIF interception
+ * by IOMMU interrupt remapping implementation.
+ * Note: Device emulation code generating an MSI is expected to provide a valid
+ * memory transaction attributes with requested_id set.
+ */
+static MemTxResult riscv_iommu_trap_write(void *opaque, hwaddr addr,
+    uint64_t data, unsigned size, MemTxAttrs attrs)
+{
+    RISCVIOMMUState* s = (RISCVIOMMUState *)opaque;
+    RISCVIOMMUContext *ctx;
+    MemTxResult res;
+    void *ref;
+    uint32_t devid = attrs.requester_id;
+
+    if (attrs.unspecified) {
+        return MEMTX_ACCESS_ERROR;
+    }
+
+    /* FIXME: PCIe bus remapping for attached endpoints. */
+    devid |= s->bus << 8;
+
+    ctx = riscv_iommu_ctx(s, devid, 0, &ref);
+    if (ctx == NULL) {
+        res = MEMTX_ACCESS_ERROR;
+    } else {
+        res = riscv_iommu_msi_write(s, ctx, addr, data, size, attrs);
+    }
+    riscv_iommu_ctx_put(s, ref);
+    return res;
+}
+
+static MemTxResult riscv_iommu_trap_read(void *opaque, hwaddr addr,
+    uint64_t *data, unsigned size, MemTxAttrs attrs)
+{
+    return MEMTX_ACCESS_ERROR;
+}
+
+static const MemoryRegionOps riscv_iommu_trap_ops = {
+    .read_with_attrs = riscv_iommu_trap_read,
+    .write_with_attrs = riscv_iommu_trap_write,
+    .endianness = DEVICE_LITTLE_ENDIAN,
+    .impl = {
+        .min_access_size = 1,
+        .max_access_size = 8,
+        .unaligned = true,
+    },
+    .valid = {
+        .min_access_size = 1,
+        .max_access_size = 8,
+    }
+};
+
+static void riscv_iommu_realize(DeviceState *dev, Error **errp)
+{
+    RISCVIOMMUState *s = RISCV_IOMMU(dev);
+
+    s->cap = s->version & RISCV_IOMMU_CAP_VERSION;
+    if (s->enable_msi) {
+        s->cap |= RISCV_IOMMU_CAP_MSI_FLAT | RISCV_IOMMU_CAP_MSI_MRIF;
+    }
+    /* Report QEMU target physical address space limits */
+    s->cap = set_field(s->cap, RISCV_IOMMU_CAP_PAS,
+                       TARGET_PHYS_ADDR_SPACE_BITS);
+
+    /* TODO: method to report supported PASID bits */
+    s->pasid_bits = 8; /* restricted to size of MemTxAttrs.pasid */
+    s->cap |= RISCV_IOMMU_CAP_PD8;
+
+    /* Out-of-reset translation mode: OFF (DMA disabled) BARE (passthrough) */
+    s->ddtp = set_field(0, RISCV_IOMMU_DDTP_MODE, s->enable_off ?
+                        RISCV_IOMMU_DDTP_MODE_OFF : 
RISCV_IOMMU_DDTP_MODE_BARE);
+
+    /* register storage */
+    s->regs_rw = g_new0(uint8_t, RISCV_IOMMU_REG_SIZE);
+    s->regs_ro = g_new0(uint8_t, RISCV_IOMMU_REG_SIZE);
+    s->regs_wc = g_new0(uint8_t, RISCV_IOMMU_REG_SIZE);
+
+     /* Mark all registers read-only */
+    memset(s->regs_ro, 0xff, RISCV_IOMMU_REG_SIZE);
+
+    /*
+     * Register complete MMIO space, including MSI/PBA registers.
+     * Note, PCIDevice implementation will add overlapping MR for MSI/PBA,
+     * managed directly by the PCIDevice implementation.
+     */
+    memory_region_init_io(&s->regs_mr, OBJECT(dev), &riscv_iommu_mmio_ops, s,
+        "riscv-iommu-regs", RISCV_IOMMU_REG_SIZE);
+
+    /* Set power-on register state */
+    stq_le_p(&s->regs_rw[RISCV_IOMMU_REG_CAP], s->cap);
+    stq_le_p(&s->regs_rw[RISCV_IOMMU_REG_FCTL], s->fctl);
+    stq_le_p(&s->regs_ro[RISCV_IOMMU_REG_DDTP],
+        ~(RISCV_IOMMU_DDTP_PPN | RISCV_IOMMU_DDTP_MODE));
+    stq_le_p(&s->regs_ro[RISCV_IOMMU_REG_CQB],
+        ~(RISCV_IOMMU_CQB_LOG2SZ | RISCV_IOMMU_CQB_PPN));
+    stq_le_p(&s->regs_ro[RISCV_IOMMU_REG_FQB],
+        ~(RISCV_IOMMU_FQB_LOG2SZ | RISCV_IOMMU_FQB_PPN));
+    stq_le_p(&s->regs_ro[RISCV_IOMMU_REG_PQB],
+        ~(RISCV_IOMMU_PQB_LOG2SZ | RISCV_IOMMU_PQB_PPN));
+    stl_le_p(&s->regs_wc[RISCV_IOMMU_REG_CQCSR], RISCV_IOMMU_CQCSR_CQMF |
+        RISCV_IOMMU_CQCSR_CMD_TO | RISCV_IOMMU_CQCSR_CMD_ILL);
+    stl_le_p(&s->regs_ro[RISCV_IOMMU_REG_CQCSR], RISCV_IOMMU_CQCSR_CQON |
+        RISCV_IOMMU_CQCSR_BUSY);
+    stl_le_p(&s->regs_wc[RISCV_IOMMU_REG_FQCSR], RISCV_IOMMU_FQCSR_FQMF |
+        RISCV_IOMMU_FQCSR_FQOF);
+    stl_le_p(&s->regs_ro[RISCV_IOMMU_REG_FQCSR], RISCV_IOMMU_FQCSR_FQON |
+        RISCV_IOMMU_FQCSR_BUSY);
+    stl_le_p(&s->regs_wc[RISCV_IOMMU_REG_PQCSR], RISCV_IOMMU_PQCSR_PQMF |
+        RISCV_IOMMU_PQCSR_PQOF);
+    stl_le_p(&s->regs_ro[RISCV_IOMMU_REG_PQCSR], RISCV_IOMMU_PQCSR_PQON |
+        RISCV_IOMMU_PQCSR_BUSY);
+    stl_le_p(&s->regs_wc[RISCV_IOMMU_REG_IPSR], ~0);
+    stl_le_p(&s->regs_ro[RISCV_IOMMU_REG_IVEC], 0);
+    stq_le_p(&s->regs_rw[RISCV_IOMMU_REG_DDTP], s->ddtp);
+
+    /* Memory region for downstream access, if specified. */
+    if (s->target_mr) {
+        s->target_as = g_new0(AddressSpace, 1);
+        address_space_init(s->target_as, s->target_mr,
+            "riscv-iommu-downstream");
+    } else {
+        /* Fallback to global system memory. */
+        s->target_as = &address_space_memory;
+    }
+
+    /* Memory region for untranslated MRIF/MSI writes */
+    memory_region_init_io(&s->trap_mr, OBJECT(dev), &riscv_iommu_trap_ops, s,
+            "riscv-iommu-trap", ~0ULL);
+    address_space_init(&s->trap_as, &s->trap_mr, "riscv-iommu-trap-as");
+
+    /* Device translation context cache */
+    s->ctx_cache = g_hash_table_new_full(__ctx_hash, __ctx_equal,
+                                         g_free, NULL);
+
+    s->iommus.le_next = NULL;
+    s->iommus.le_prev = NULL;
+    QLIST_INIT(&s->spaces);
+    qemu_cond_init(&s->core_cond);
+    qemu_mutex_init(&s->core_lock);
+    qemu_spin_init(&s->regs_lock);
+    qemu_thread_create(&s->core_proc, "riscv-iommu-core",
+        riscv_iommu_core_proc, s, QEMU_THREAD_JOINABLE);
+}
+
+static void riscv_iommu_unrealize(DeviceState *dev)
+{
+    RISCVIOMMUState *s = RISCV_IOMMU(dev);
+
+    qemu_mutex_lock(&s->core_lock);
+    /* cancel pending operations and stop */
+    s->core_exec = BIT(RISCV_IOMMU_EXEC_EXIT);
+    qemu_cond_signal(&s->core_cond);
+    qemu_mutex_unlock(&s->core_lock);
+    qemu_thread_join(&s->core_proc);
+    qemu_cond_destroy(&s->core_cond);
+    qemu_mutex_destroy(&s->core_lock);
+    g_hash_table_unref(s->ctx_cache);
+}
+
+static Property riscv_iommu_properties[] = {
+    DEFINE_PROP_UINT32("version", RISCVIOMMUState, version,
+        RISCV_IOMMU_SPEC_DOT_VER),
+    DEFINE_PROP_UINT32("bus", RISCVIOMMUState, bus, 0x0),
+    DEFINE_PROP_BOOL("intremap", RISCVIOMMUState, enable_msi, TRUE),
+    DEFINE_PROP_BOOL("off", RISCVIOMMUState, enable_off, TRUE),
+    DEFINE_PROP_LINK("downstream-mr", RISCVIOMMUState, target_mr,
+        TYPE_MEMORY_REGION, MemoryRegion *),
+    DEFINE_PROP_END_OF_LIST(),
+};
+
+static void riscv_iommu_class_init(ObjectClass *klass, void* data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+
+    /* internal device for riscv-iommu-{pci/sys}, not user-creatable */
+    dc->user_creatable = false;
+    dc->realize = riscv_iommu_realize;
+    dc->unrealize = riscv_iommu_unrealize;
+    device_class_set_props(dc, riscv_iommu_properties);
+}
+
+static const TypeInfo riscv_iommu_info = {
+    .name = TYPE_RISCV_IOMMU,
+    .parent = TYPE_DEVICE,
+    .instance_size = sizeof(RISCVIOMMUState),
+    .class_init = riscv_iommu_class_init,
+};
+
+static const char *IOMMU_FLAG_STR[] = {
+    "NA",
+    "RO",
+    "WR",
+    "RW",
+};
+
+/* RISC-V IOMMU Memory Region - Address Translation Space */
+static IOMMUTLBEntry riscv_iommu_memory_region_translate(
+    IOMMUMemoryRegion *iommu_mr, hwaddr addr,
+    IOMMUAccessFlags flag, int iommu_idx)
+{
+    RISCVIOMMUSpace *as = container_of(iommu_mr, RISCVIOMMUSpace, iova_mr);
+    RISCVIOMMUContext *ctx;
+    void *ref;
+    IOMMUTLBEntry iotlb = {
+        .iova = addr,
+        .target_as = as->iommu->target_as,
+        .addr_mask = ~0ULL,
+        .perm = flag,
+    };
+
+    ctx = riscv_iommu_ctx(as->iommu, as->devid, iommu_idx, &ref);
+    if (ctx == NULL) {
+        /* Translation disabled or invalid. */
+        iotlb.addr_mask = 0;
+        iotlb.perm = IOMMU_NONE;
+    } else if (riscv_iommu_translate(as->iommu, ctx, &iotlb)) {
+        /* Translation disabled or fault reported. */
+        iotlb.addr_mask = 0;
+        iotlb.perm = IOMMU_NONE;
+    }
+
+    /* Trace all dma translations with original access flags. */
+    trace_riscv_iommu_dma(as->iommu->parent_obj.id, PCI_BUS_NUM(as->devid),
+                          PCI_SLOT(as->devid), PCI_FUNC(as->devid), iommu_idx,
+                          IOMMU_FLAG_STR[flag & IOMMU_RW], iotlb.iova,
+                          iotlb.translated_addr);
+
+    riscv_iommu_ctx_put(as->iommu, ref);
+
+    return iotlb;
+}
+
+static int riscv_iommu_memory_region_notify(
+    IOMMUMemoryRegion *iommu_mr, IOMMUNotifierFlag old,
+    IOMMUNotifierFlag new, Error **errp)
+{
+    RISCVIOMMUSpace *as = container_of(iommu_mr, RISCVIOMMUSpace, iova_mr);
+
+    if (old == IOMMU_NOTIFIER_NONE) {
+        as->notifier = true;
+        trace_riscv_iommu_notifier_add(iommu_mr->parent_obj.name);
+    } else if (new == IOMMU_NOTIFIER_NONE) {
+        as->notifier = false;
+        trace_riscv_iommu_notifier_del(iommu_mr->parent_obj.name);
+    }
+
+    return 0;
+}
+
+static inline bool pci_is_iommu(PCIDevice *pdev)
+{
+    return pci_get_word(pdev->config + PCI_CLASS_DEVICE) == 0x0806;
+}
+
+static AddressSpace *riscv_iommu_find_as(PCIBus *bus, void *opaque, int devfn)
+{
+    RISCVIOMMUState *s = (RISCVIOMMUState *) opaque;
+    PCIDevice *pdev = pci_find_device(bus, pci_bus_num(bus), devfn);
+    AddressSpace *as = NULL;
+
+    if (pdev && pci_is_iommu(pdev)) {
+        return s->target_as;
+    }
+
+    /* Find first registered IOMMU device */
+    while (s->iommus.le_prev) {
+        s = *(s->iommus.le_prev);
+    }
+
+    /* Find first matching IOMMU */
+    while (s != NULL && as == NULL) {
+        as = riscv_iommu_space(s, PCI_BUILD_BDF(pci_bus_num(bus), devfn));
+        s = s->iommus.le_next;
+    }
+
+    return as ? as : &address_space_memory;
+}
+
+static const PCIIOMMUOps riscv_iommu_ops = {
+    .get_address_space = riscv_iommu_find_as,
+};
+
+void riscv_iommu_pci_setup_iommu(RISCVIOMMUState *iommu, PCIBus *bus,
+        Error **errp)
+{
+    if (bus->iommu_ops &&
+        bus->iommu_ops->get_address_space == riscv_iommu_find_as) {
+        /* Allow multiple IOMMUs on the same PCIe bus, link known devices */
+        RISCVIOMMUState *last = (RISCVIOMMUState *)bus->iommu_opaque;
+        QLIST_INSERT_AFTER(last, iommu, iommus);
+    } else if (bus->iommu_ops == NULL) {
+        pci_setup_iommu(bus, &riscv_iommu_ops, iommu);
+    } else {
+        error_setg(errp, "can't register secondary IOMMU for PCI bus #%d",
+            pci_bus_num(bus));
+    }
+}
+
+static int riscv_iommu_memory_region_index(IOMMUMemoryRegion *iommu_mr,
+    MemTxAttrs attrs)
+{
+    return attrs.unspecified ? RISCV_IOMMU_NOPASID : (int)attrs.pasid;
+}
+
+static int riscv_iommu_memory_region_index_len(IOMMUMemoryRegion *iommu_mr)
+{
+    RISCVIOMMUSpace *as = container_of(iommu_mr, RISCVIOMMUSpace, iova_mr);
+    return 1 << as->iommu->pasid_bits;
+}
+
+static void riscv_iommu_memory_region_init(ObjectClass *klass, void *data)
+{
+    IOMMUMemoryRegionClass *imrc = IOMMU_MEMORY_REGION_CLASS(klass);
+
+    imrc->translate = riscv_iommu_memory_region_translate;
+    imrc->notify_flag_changed = riscv_iommu_memory_region_notify;
+    imrc->attrs_to_index = riscv_iommu_memory_region_index;
+    imrc->num_indexes = riscv_iommu_memory_region_index_len;
+}
+
+static const TypeInfo riscv_iommu_memory_region_info = {
+    .parent = TYPE_IOMMU_MEMORY_REGION,
+    .name = TYPE_RISCV_IOMMU_MEMORY_REGION,
+    .class_init = riscv_iommu_memory_region_init,
+};
+
+static void riscv_iommu_register_mr_types(void)
+{
+    type_register_static(&riscv_iommu_memory_region_info);
+    type_register_static(&riscv_iommu_info);
+}
+
+type_init(riscv_iommu_register_mr_types);
diff --git a/hw/riscv/riscv-iommu.h b/hw/riscv/riscv-iommu.h
new file mode 100644
index 0000000000..6f740de690
--- /dev/null
+++ b/hw/riscv/riscv-iommu.h
@@ -0,0 +1,141 @@
+/*
+ * QEMU emulation of an RISC-V IOMMU (Ziommu)
+ *
+ * Copyright (C) 2022-2023 Rivos Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef HW_RISCV_IOMMU_STATE_H
+#define HW_RISCV_IOMMU_STATE_H
+
+#include "qemu/osdep.h"
+#include "qom/object.h"
+
+#include "hw/riscv/iommu.h"
+
+struct RISCVIOMMUState {
+    /*< private >*/
+    DeviceState parent_obj;
+
+    /*< public >*/
+    uint32_t version;     /* Reported interface version number */
+    uint32_t pasid_bits;  /* process identifier width */
+    uint32_t bus;         /* PCI bus mapping for non-root endpoints */
+
+    uint64_t cap;         /* IOMMU supported capabilities */
+    uint64_t fctl;        /* IOMMU enabled features */
+
+    bool enable_off;      /* Enable out-of-reset OFF mode (DMA disabled) */
+    bool enable_msi;      /* Enable MSI remapping */
+
+    /* IOMMU Internal State */
+    uint64_t ddtp;        /* Validated Device Directory Tree Root Pointer */
+
+    dma_addr_t cq_addr;   /* Command queue base physical address */
+    dma_addr_t fq_addr;   /* Fault/event queue base physical address */
+    dma_addr_t pq_addr;   /* Page request queue base physical address */
+
+    uint32_t cq_mask;     /* Command queue index bit mask */
+    uint32_t fq_mask;     /* Fault/event queue index bit mask */
+    uint32_t pq_mask;     /* Page request queue index bit mask */
+
+    /* interrupt notifier */
+    void (*notify)(RISCVIOMMUState *iommu, unsigned vector);
+
+    /* IOMMU State Machine */
+    QemuThread core_proc; /* Background processing thread */
+    QemuMutex core_lock;  /* Global IOMMU lock, used for cache/regs updates */
+    QemuCond core_cond;   /* Background processing wake up signal */
+    unsigned core_exec;   /* Processing thread execution actions */
+
+    /* IOMMU target address space */
+    AddressSpace *target_as;
+    MemoryRegion *target_mr;
+
+    /* MSI / MRIF access trap */
+    AddressSpace trap_as;
+    MemoryRegion trap_mr;
+
+    GHashTable *ctx_cache;          /* Device translation Context Cache */
+
+    /* MMIO Hardware Interface */
+    MemoryRegion regs_mr;
+    QemuSpin regs_lock;
+    uint8_t *regs_rw;  /* register state (user write) */
+    uint8_t *regs_wc;  /* write-1-to-clear mask */
+    uint8_t *regs_ro;  /* read-only mask */
+
+    QLIST_ENTRY(RISCVIOMMUState) iommus;
+    QLIST_HEAD(, RISCVIOMMUSpace) spaces;
+};
+
+void riscv_iommu_pci_setup_iommu(RISCVIOMMUState *iommu, PCIBus *bus,
+         Error **errp);
+
+/* private helpers */
+
+/* Register helper functions */
+static inline uint32_t riscv_iommu_reg_mod32(RISCVIOMMUState *s,
+    unsigned idx, uint32_t set, uint32_t clr)
+{
+    uint32_t val;
+    qemu_spin_lock(&s->regs_lock);
+    val = ldl_le_p(s->regs_rw + idx);
+    stl_le_p(s->regs_rw + idx, (val & ~clr) | set);
+    qemu_spin_unlock(&s->regs_lock);
+    return val;
+}
+
+static inline void riscv_iommu_reg_set32(RISCVIOMMUState *s,
+    unsigned idx, uint32_t set)
+{
+    qemu_spin_lock(&s->regs_lock);
+    stl_le_p(s->regs_rw + idx, set);
+    qemu_spin_unlock(&s->regs_lock);
+}
+
+static inline uint32_t riscv_iommu_reg_get32(RISCVIOMMUState *s,
+    unsigned idx)
+{
+    return ldl_le_p(s->regs_rw + idx);
+}
+
+static inline uint64_t riscv_iommu_reg_mod64(RISCVIOMMUState *s,
+    unsigned idx, uint64_t set, uint64_t clr)
+{
+    uint64_t val;
+    qemu_spin_lock(&s->regs_lock);
+    val = ldq_le_p(s->regs_rw + idx);
+    stq_le_p(s->regs_rw + idx, (val & ~clr) | set);
+    qemu_spin_unlock(&s->regs_lock);
+    return val;
+}
+
+static inline void riscv_iommu_reg_set64(RISCVIOMMUState *s,
+    unsigned idx, uint64_t set)
+{
+    qemu_spin_lock(&s->regs_lock);
+    stq_le_p(s->regs_rw + idx, set);
+    qemu_spin_unlock(&s->regs_lock);
+}
+
+static inline uint64_t riscv_iommu_reg_get64(RISCVIOMMUState *s,
+    unsigned idx)
+{
+    return ldq_le_p(s->regs_rw + idx);
+}
+
+
+
+#endif
diff --git a/hw/riscv/trace-events b/hw/riscv/trace-events
new file mode 100644
index 0000000000..42a97caffa
--- /dev/null
+++ b/hw/riscv/trace-events
@@ -0,0 +1,11 @@
+# See documentation at docs/devel/tracing.rst
+
+# riscv-iommu.c
+riscv_iommu_new(const char *id, unsigned b, unsigned d, unsigned f) "%s: 
device attached %04x:%02x.%d"
+riscv_iommu_flt(const char *id, unsigned b, unsigned d, unsigned f, uint64_t 
reason, uint64_t iova) "%s: fault %04x:%02x.%u reason: 0x%"PRIx64" iova: 
0x%"PRIx64
+riscv_iommu_pri(const char *id, unsigned b, unsigned d, unsigned f, uint64_t 
iova) "%s: page request %04x:%02x.%u iova: 0x%"PRIx64
+riscv_iommu_dma(const char *id, unsigned b, unsigned d, unsigned f, unsigned 
pasid, const char *dir, uint64_t iova, uint64_t phys) "%s: translate 
%04x:%02x.%u #%u %s 0x%"PRIx64" -> 0x%"PRIx64
+riscv_iommu_msi(const char *id, unsigned b, unsigned d, unsigned f, uint64_t 
iova, uint64_t phys) "%s: translate %04x:%02x.%u MSI 0x%"PRIx64" -> 0x%"PRIx64
+riscv_iommu_cmd(const char *id, uint64_t l, uint64_t u) "%s: command 
0x%"PRIx64" 0x%"PRIx64
+riscv_iommu_notifier_add(const char *id) "%s: dev-iotlb notifier added"
+riscv_iommu_notifier_del(const char *id) "%s: dev-iotlb notifier removed"
diff --git a/hw/riscv/trace.h b/hw/riscv/trace.h
new file mode 100644
index 0000000000..b88504b750
--- /dev/null
+++ b/hw/riscv/trace.h
@@ -0,0 +1,2 @@
+#include "trace/trace-hw_riscv.h"
+
diff --git a/include/hw/riscv/iommu.h b/include/hw/riscv/iommu.h
new file mode 100644
index 0000000000..403b365893
--- /dev/null
+++ b/include/hw/riscv/iommu.h
@@ -0,0 +1,36 @@
+/*
+ * QEMU emulation of an RISC-V IOMMU (Ziommu)
+ *
+ * Copyright (C) 2022-2023 Rivos Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef HW_RISCV_IOMMU_H
+#define HW_RISCV_IOMMU_H
+
+#include "qemu/osdep.h"
+#include "qom/object.h"
+
+#define TYPE_RISCV_IOMMU "riscv-iommu"
+OBJECT_DECLARE_SIMPLE_TYPE(RISCVIOMMUState, RISCV_IOMMU)
+typedef struct RISCVIOMMUState RISCVIOMMUState;
+
+#define TYPE_RISCV_IOMMU_MEMORY_REGION "riscv-iommu-mr"
+typedef struct RISCVIOMMUSpace RISCVIOMMUSpace;
+
+#define TYPE_RISCV_IOMMU_PCI "riscv-iommu-pci"
+OBJECT_DECLARE_SIMPLE_TYPE(RISCVIOMMUStatePci, RISCV_IOMMU_PCI)
+typedef struct RISCVIOMMUStatePci RISCVIOMMUStatePci;
+
+#endif
diff --git a/meson.build b/meson.build
index c59ca496f2..75e56f3282 100644
--- a/meson.build
+++ b/meson.build
@@ -3361,6 +3361,7 @@ if have_system
     'hw/rdma',
     'hw/rdma/vmw',
     'hw/rtc',
+    'hw/riscv',
     'hw/s390x',
     'hw/scsi',
     'hw/sd',
-- 
2.43.2