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Re: [PATCH v4 11/14] vfio-user: IOMMU support for remote device
From: |
Stefan Hajnoczi |
Subject: |
Re: [PATCH v4 11/14] vfio-user: IOMMU support for remote device |
Date: |
Thu, 16 Dec 2021 14:40:25 +0000 |
On Wed, Dec 15, 2021 at 10:35:35AM -0500, Jagannathan Raman wrote:
> Assign separate address space for each device in the remote processes.
If I understand correctly this isn't really an IOMMU. It's abusing the
IOMMU APIs to create isolated address spaces for each device. This way
memory regions added by the vfio-user client do not conflict when there
are multiple vfio-user servers.
Calling pci_root_bus_new() and keeping one PCI bus per VfuObject might
be a cleaner approach:
- Lets you isolate both PCI Memory Space and IO Space.
- Isolates the PCIDevices and their addresses on the bus.
- Isolates irqs.
- No more need to abuse the IOMMU API.
I might be missing something because I haven't investigated how to do
this myself.
> Signed-off-by: Elena Ufimtseva <elena.ufimtseva@oracle.com>
> Signed-off-by: John G Johnson <john.g.johnson@oracle.com>
> Signed-off-by: Jagannathan Raman <jag.raman@oracle.com>
> ---
> include/hw/pci/pci.h | 2 +
> include/hw/remote/iommu.h | 24 ++++++++
> hw/pci/pci.c | 2 +-
> hw/remote/iommu.c | 117 ++++++++++++++++++++++++++++++++++++++
> hw/remote/machine.c | 5 ++
> hw/remote/vfio-user-obj.c | 20 ++++++-
> MAINTAINERS | 2 +
> hw/remote/meson.build | 1 +
> 8 files changed, 169 insertions(+), 4 deletions(-)
> create mode 100644 include/hw/remote/iommu.h
> create mode 100644 hw/remote/iommu.c
>
> diff --git a/include/hw/pci/pci.h b/include/hw/pci/pci.h
> index 5c4016b995..f2fc2d5375 100644
> --- a/include/hw/pci/pci.h
> +++ b/include/hw/pci/pci.h
> @@ -734,6 +734,8 @@ void lsi53c8xx_handle_legacy_cmdline(DeviceState
> *lsi_dev);
> qemu_irq pci_allocate_irq(PCIDevice *pci_dev);
> void pci_set_irq(PCIDevice *pci_dev, int level);
>
> +void pci_init_bus_master(PCIDevice *pci_dev);
This function isn't used in this patch. Why make it public?
> +
> static inline void pci_irq_assert(PCIDevice *pci_dev)
> {
> pci_set_irq(pci_dev, 1);
> diff --git a/include/hw/remote/iommu.h b/include/hw/remote/iommu.h
> new file mode 100644
> index 0000000000..42ce0ca383
> --- /dev/null
> +++ b/include/hw/remote/iommu.h
> @@ -0,0 +1,24 @@
> +/*
> + * IOMMU for remote device
> + *
> + * Copyright © 2021 Oracle and/or its affiliates.
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2 or later.
> + * See the COPYING file in the top-level directory.
> + *
> + */
> +
> +#ifndef REMOTE_IOMMU_H
> +#define REMOTE_IOMMU_H
> +
> +#include "hw/pci/pci_bus.h"
> +
> +void remote_iommu_free(PCIDevice *pci_dev);
> +
> +void remote_iommu_init(void);
> +
> +void remote_iommu_set(PCIBus *bus);
> +
> +MemoryRegion *remote_iommu_get_ram(PCIDevice *pci_dev);
> +
> +#endif
> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> index 4a84e478ce..57d561cc03 100644
> --- a/hw/pci/pci.c
> +++ b/hw/pci/pci.c
> @@ -95,7 +95,7 @@ static const VMStateDescription vmstate_pcibus = {
> }
> };
>
> -static void pci_init_bus_master(PCIDevice *pci_dev)
> +void pci_init_bus_master(PCIDevice *pci_dev)
> {
> AddressSpace *dma_as = pci_device_iommu_address_space(pci_dev);
>
> diff --git a/hw/remote/iommu.c b/hw/remote/iommu.c
> new file mode 100644
> index 0000000000..30c866badb
> --- /dev/null
> +++ b/hw/remote/iommu.c
> @@ -0,0 +1,117 @@
> +/*
> + * Remote IOMMU
> + *
> + * Copyright © 2021 Oracle and/or its affiliates.
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2 or later.
> + * See the COPYING file in the top-level directory.
> + *
> + */
> +
> +#include "qemu/osdep.h"
> +#include "qemu-common.h"
> +
> +#include "hw/remote/iommu.h"
> +#include "hw/pci/pci_bus.h"
> +#include "exec/memory.h"
> +#include "exec/address-spaces.h"
> +#include "trace.h"
> +
> +struct VFUIOMMU {
> + AddressSpace as;
> + MemoryRegion mr;
I guess this is the root MemoryRegion container? Calling it "root" or
"root_mr" instead of "mr" would make that clearer.
> +};
> +
> +typedef struct VFUPciBus {
There is no uppercase/lowercase consistency between VfuObject vs
VFUIOMMU vs VFUPciBus. Although the coding standard doesn't dictate ABC
vs Abc, please be consistent. I suggest following the VfuObject
convention started in the previous patches. The names would be VfuIommu
and VfuPciBus.
> + PCIBus *bus;
> + struct VFUIOMMU *iommu[];
> +} VFUPciBus;
> +
> +GHashTable *remote_as_table;
> +
> +static AddressSpace *remote_iommu_get_as(PCIBus *bus, void *opaque, int
> devfn)
> +{
> + VFUPciBus *vfu_pci_bus = NULL;
> + struct VFUIOMMU *iommu = NULL;
> +
> + if (!remote_as_table) {
> + return &address_space_memory;
> + }
> +
> + vfu_pci_bus = g_hash_table_lookup(remote_as_table, bus);
> +
> + if (!vfu_pci_bus) {
> + vfu_pci_bus = g_malloc0(sizeof(VFUPciBus));
> + vfu_pci_bus->bus = bus;
> + g_hash_table_insert(remote_as_table, bus, vfu_pci_bus);
> + }
> +
> + iommu = vfu_pci_bus->iommu[devfn];
> +
> + if (!iommu) {
> + g_autofree char *mr_name = g_strdup_printf("vfu-ram-%d", devfn);
> + g_autofree char *as_name = g_strdup_printf("vfu-as-%d", devfn);
> +
> + iommu = g_malloc0(sizeof(struct VFUIOMMU));
> +
> + memory_region_init(&iommu->mr, NULL, mr_name, UINT64_MAX);
> + address_space_init(&iommu->as, &iommu->mr, as_name);
> +
> + vfu_pci_bus->iommu[devfn] = iommu;
> + }
> +
> + return &iommu->as;
> +}
> +
> +void remote_iommu_free(PCIDevice *pci_dev)
> +{
> + VFUPciBus *vfu_pci_bus = NULL;
> + struct VFUIOMMU *iommu = NULL;
> +
> + if (!remote_as_table) {
> + return;
> + }
> +
> + vfu_pci_bus = g_hash_table_lookup(remote_as_table, pci_get_bus(pci_dev));
> +
> + if (!vfu_pci_bus) {
> + return;
> + }
> +
> + iommu = vfu_pci_bus->iommu[pci_dev->devfn];
> +
> + vfu_pci_bus->iommu[pci_dev->devfn] = NULL;
> +
> + if (iommu) {
> + memory_region_unref(&iommu->mr);
> + address_space_destroy(&iommu->as);
> + g_free(iommu);
> + }
> +}
> +
> +void remote_iommu_init(void)
> +{
> + remote_as_table = g_hash_table_new_full(NULL, NULL, NULL, NULL);
> +}
> +
> +void remote_iommu_set(PCIBus *bus)
> +{
> + pci_setup_iommu(bus, remote_iommu_get_as, NULL);
> +}
> +
> +MemoryRegion *remote_iommu_get_ram(PCIDevice *pci_dev)
> +{
> + PCIBus *bus = pci_get_bus(pci_dev);
> + VFUPciBus *vfu_pci_bus;
> +
> + if (!remote_as_table) {
> + return get_system_memory();
> + }
> +
> + vfu_pci_bus = g_hash_table_lookup(remote_as_table, bus);
> + if (!vfu_pci_bus) {
> + return get_system_memory();
> + }
> +
> + return &vfu_pci_bus->iommu[pci_dev->devfn]->mr;
> +}
> diff --git a/hw/remote/machine.c b/hw/remote/machine.c
> index 952105eab5..023be0491e 100644
> --- a/hw/remote/machine.c
> +++ b/hw/remote/machine.c
> @@ -21,6 +21,7 @@
> #include "qapi/error.h"
> #include "hw/pci/pci_host.h"
> #include "hw/remote/iohub.h"
> +#include "hw/remote/iommu.h"
>
> static void remote_machine_init(MachineState *machine)
> {
> @@ -52,6 +53,10 @@ static void remote_machine_init(MachineState *machine)
>
> remote_iohub_init(&s->iohub);
>
> + remote_iommu_init();
> +
> + remote_iommu_set(pci_host->bus);
> +
> pci_bus_irqs(pci_host->bus, remote_iohub_set_irq, remote_iohub_map_irq,
> &s->iohub, REMOTE_IOHUB_NB_PIRQS);
> }
> diff --git a/hw/remote/vfio-user-obj.c b/hw/remote/vfio-user-obj.c
> index 9399e87cbe..ae375e69b9 100644
> --- a/hw/remote/vfio-user-obj.c
> +++ b/hw/remote/vfio-user-obj.c
> @@ -49,6 +49,7 @@
> #include "hw/qdev-core.h"
> #include "hw/pci/pci.h"
> #include "qemu/timer.h"
> +#include "hw/remote/iommu.h"
>
> #define TYPE_VFU_OBJECT "x-vfio-user-server"
> OBJECT_DECLARE_TYPE(VfuObject, VfuObjectClass, VFU_OBJECT)
> @@ -210,6 +211,7 @@ static ssize_t vfu_object_cfg_access(vfu_ctx_t *vfu_ctx,
> char * const buf,
>
> static void dma_register(vfu_ctx_t *vfu_ctx, vfu_dma_info_t *info)
> {
> + VfuObject *o = vfu_get_private(vfu_ctx);
> MemoryRegion *subregion = NULL;
> g_autofree char *name = NULL;
> static unsigned int suffix;
> @@ -226,14 +228,15 @@ static void dma_register(vfu_ctx_t *vfu_ctx,
> vfu_dma_info_t *info)
> memory_region_init_ram_ptr(subregion, NULL, name,
> iov->iov_len, info->vaddr);
>
> - memory_region_add_subregion(get_system_memory(), (hwaddr)iov->iov_base,
> - subregion);
> + memory_region_add_subregion(remote_iommu_get_ram(o->pci_dev),
> + (hwaddr)iov->iov_base, subregion);
>
> trace_vfu_dma_register((uint64_t)iov->iov_base, iov->iov_len);
> }
>
> static void dma_unregister(vfu_ctx_t *vfu_ctx, vfu_dma_info_t *info)
> {
> + VfuObject *o = vfu_get_private(vfu_ctx);
> MemoryRegion *mr = NULL;
> ram_addr_t offset;
>
> @@ -242,7 +245,7 @@ static void dma_unregister(vfu_ctx_t *vfu_ctx,
> vfu_dma_info_t *info)
> return;
> }
>
> - memory_region_del_subregion(get_system_memory(), mr);
> + memory_region_del_subregion(remote_iommu_get_ram(o->pci_dev), mr);
>
> object_unparent((OBJECT(mr)));
>
> @@ -320,6 +323,7 @@ static vfu_region_access_cb_t
> *vfu_object_bar_handlers[PCI_NUM_REGIONS] = {
> */
> static void vfu_object_register_bars(vfu_ctx_t *vfu_ctx, PCIDevice *pdev)
> {
> + VfuObject *o = vfu_get_private(vfu_ctx);
> int i;
>
> for (i = 0; i < PCI_NUM_REGIONS; i++) {
> @@ -332,6 +336,12 @@ static void vfu_object_register_bars(vfu_ctx_t *vfu_ctx,
> PCIDevice *pdev)
> vfu_object_bar_handlers[i],
> VFU_REGION_FLAG_RW, NULL, 0, -1, 0);
>
> + if ((o->pci_dev->io_regions[i].type & PCI_BASE_ADDRESS_SPACE) == 0) {
> + memory_region_unref(o->pci_dev->io_regions[i].address_space);
> + o->pci_dev->io_regions[i].address_space =
> + remote_iommu_get_ram(o->pci_dev);
> + }
This looks hacky. If you create a separate PCIHost for each device
instead then the BARs will be created in the MemoryRegion (confusingly
named "address_space" in the PCI code) of your choosing.
Also, why is PCI Memory Space isolated via VFUIOMMU but PCI IO Space is
not?
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- Re: [PATCH v4 08/14] vfio-user: handle PCI config space accesses, (continued)
[PATCH v4 09/14] vfio-user: handle DMA mappings, Jagannathan Raman, 2021/12/15
[PATCH v4 10/14] vfio-user: handle PCI BAR accesses, Jagannathan Raman, 2021/12/15
[PATCH v4 11/14] vfio-user: IOMMU support for remote device, Jagannathan Raman, 2021/12/15
- Re: [PATCH v4 11/14] vfio-user: IOMMU support for remote device,
Stefan Hajnoczi <=
[PATCH v4 12/14] vfio-user: handle device interrupts, Jagannathan Raman, 2021/12/15
[PATCH v4 13/14] vfio-user: register handlers to facilitate migration, Jagannathan Raman, 2021/12/15
[PATCH v4 14/14] vfio-user: avocado tests for vfio-user, Jagannathan Raman, 2021/12/15
[PATCH v4 04/14] vfio-user: define vfio-user-server object, Jagannathan Raman, 2021/12/15