[PATCH v5 1/2] vfio: move function vfio_get_xlat_addr() to memory.c

[Cindy Lu]

- Move the function vfio_get_xlat_addr to softmmu/memory.c, and
  change the name to memory_get_xlat_addr(). So we can use this
  function on other devices, such as vDPA device.
- Add a new bool arg in this function, which shows whether the memory is
  backed by a discard manager. So the device can have its own warning.

Signed-off-by: Cindy Lu <lulu@redhat.com>
---
 hw/vfio/common.c      | 163 +++++++++++++++++++-----------------------
 include/exec/memory.h |   4 ++
 softmmu/memory.c      |  69 ++++++++++++++++++
 3 files changed, 146 insertions(+), 90 deletions(-)

diff --git a/hw/vfio/common.c b/hw/vfio/common.c
index ace9562a9b..e958a4435f 100644
--- a/hw/vfio/common.c
+++ b/hw/vfio/common.c
@@ -574,92 +574,6 @@ static bool 
vfio_listener_skipped_section(MemoryRegionSection *section)
            section->offset_within_address_space & (1ULL << 63);
 }
 
-/* Called with rcu_read_lock held.  */
-static bool vfio_get_xlat_addr(IOMMUTLBEntry *iotlb, void **vaddr,
-                               ram_addr_t *ram_addr, bool *read_only)
-{
-    MemoryRegion *mr;
-    hwaddr xlat;
-    hwaddr len = iotlb->addr_mask + 1;
-    bool writable = iotlb->perm & IOMMU_WO;
-
-    /*
-     * The IOMMU TLB entry we have just covers translation through
-     * this IOMMU to its immediate target.  We need to translate
-     * it the rest of the way through to memory.
-     */
-    mr = address_space_translate(&address_space_memory,
-                                 iotlb->translated_addr,
-                                 &xlat, &len, writable,
-                                 MEMTXATTRS_UNSPECIFIED);
-    if (!memory_region_is_ram(mr)) {
-        error_report("iommu map to non memory area %"HWADDR_PRIx"",
-                     xlat);
-        return false;
-    } else if (memory_region_has_ram_discard_manager(mr)) {
-        RamDiscardManager *rdm = memory_region_get_ram_discard_manager(mr);
-        MemoryRegionSection tmp = {
-            .mr = mr,
-            .offset_within_region = xlat,
-            .size = int128_make64(len),
-        };
-
-        /*
-         * Malicious VMs can map memory into the IOMMU, which is expected
-         * to remain discarded. vfio will pin all pages, populating memory.
-         * Disallow that. vmstate priorities make sure any RamDiscardManager
-         * were already restored before IOMMUs are restored.
-         */
-        if (!ram_discard_manager_is_populated(rdm, &tmp)) {
-            error_report("iommu map to discarded memory (e.g., unplugged via"
-                         " virtio-mem): %"HWADDR_PRIx"",
-                         iotlb->translated_addr);
-            return false;
-        }
-
-        /*
-         * Malicious VMs might trigger discarding of IOMMU-mapped memory. The
-         * pages will remain pinned inside vfio until unmapped, resulting in a
-         * higher memory consumption than expected. If memory would get
-         * populated again later, there would be an inconsistency between pages
-         * pinned by vfio and pages seen by QEMU. This is the case until
-         * unmapped from the IOMMU (e.g., during device reset).
-         *
-         * With malicious guests, we really only care about pinning more memory
-         * than expected. RLIMIT_MEMLOCK set for the user/process can never be
-         * exceeded and can be used to mitigate this problem.
-         */
-        warn_report_once("Using vfio with vIOMMUs and coordinated discarding 
of"
-                         " RAM (e.g., virtio-mem) works, however, malicious"
-                         " guests can trigger pinning of more memory than"
-                         " intended via an IOMMU. It's possible to mitigate "
-                         " by setting/adjusting RLIMIT_MEMLOCK.");
-    }
-
-    /*
-     * Translation truncates length to the IOMMU page size,
-     * check that it did not truncate too much.
-     */
-    if (len & iotlb->addr_mask) {
-        error_report("iommu has granularity incompatible with target AS");
-        return false;
-    }
-
-    if (vaddr) {
-        *vaddr = memory_region_get_ram_ptr(mr) + xlat;
-    }
-
-    if (ram_addr) {
-        *ram_addr = memory_region_get_ram_addr(mr) + xlat;
-    }
-
-    if (read_only) {
-        *read_only = !writable || mr->readonly;
-    }
-
-    return true;
-}
-
 static void vfio_iommu_map_notify(IOMMUNotifier *n, IOMMUTLBEntry *iotlb)
 {
     VFIOGuestIOMMU *giommu = container_of(n, VFIOGuestIOMMU, n);
@@ -681,10 +595,46 @@ static void vfio_iommu_map_notify(IOMMUNotifier *n, 
IOMMUTLBEntry *iotlb)
 
     if ((iotlb->perm & IOMMU_RW) != IOMMU_NONE) {
         bool read_only;
-
-        if (!vfio_get_xlat_addr(iotlb, &vaddr, NULL, &read_only)) {
+        bool mr_has_discard_manager;
+
+        if (!memory_get_xlat_addr(iotlb, &vaddr, NULL, &read_only,
+                                  &mr_has_discard_manager)) {
+            if (mr_has_discard_manager) {
+                /*
+                 * Malicious VMs can map memory into the IOMMU, which is
+                 * expected to remain discarded. vfio will pin all pages,
+                 * populating memory. Disallow that. vmstate priorities make
+                 * sure any RamDiscardManager were already restored before
+                 * IOMMUs are restored.
+                 */
+
+                error_report(
+                    "iommu map to discarded memory (e.g., unplugged via"
+                    " virtio-mem): %" HWADDR_PRIx "",
+                    iotlb->translated_addr);
+            }
             goto out;
         }
+        if (mr_has_discard_manager) {
+            /*
+             * Malicious VMs might trigger discarding of IOMMU-mapped memory.
+             * The pages will remain pinned inside vfio until unmapped,
+             * resulting in a higher memory consumption than expected. If 
memory
+             * would get populated again later, there would be an inconsistency
+             * between pages pinned by vfio and pages seen by QEMU. This is the
+             * case until unmapped from the IOMMU (e.g., during device reset).
+             *
+             * With malicious guests, we really only care about pinning more
+             * memory than expected. RLIMIT_MEMLOCK set for the user/process 
can
+             * never be exceeded and can be used to mitigate this problem.
+             */
+            warn_report_once(
+                "Using vfio with vIOMMUs and coordinated discarding of"
+                " RAM (e.g., virtio-mem) works, however, malicious"
+                " guests can trigger pinning of more memory than"
+                " intended via an IOMMU. It's possible to mitigate "
+                " by setting/adjusting RLIMIT_MEMLOCK.");
+        }
         /*
          * vaddr is only valid until rcu_read_unlock(). But after
          * vfio_dma_map has set up the mapping the pages will be
@@ -1349,6 +1299,7 @@ static void vfio_iommu_map_dirty_notify(IOMMUNotifier *n, 
IOMMUTLBEntry *iotlb)
     VFIOContainer *container = giommu->container;
     hwaddr iova = iotlb->iova + giommu->iommu_offset;
     ram_addr_t translated_addr;
+    bool mr_has_discard_manager;
 
     trace_vfio_iommu_map_dirty_notify(iova, iova + iotlb->addr_mask);
 
@@ -1359,9 +1310,9 @@ static void vfio_iommu_map_dirty_notify(IOMMUNotifier *n, 
IOMMUTLBEntry *iotlb)
     }
 
     rcu_read_lock();
-    if (vfio_get_xlat_addr(iotlb, NULL, &translated_addr, NULL)) {
+    if (memory_get_xlat_addr(iotlb, NULL, &translated_addr, NULL,
+                             &mr_has_discard_manager)) {
         int ret;
-
         ret = vfio_get_dirty_bitmap(container, iova, iotlb->addr_mask + 1,
                                     translated_addr);
         if (ret) {
@@ -1370,6 +1321,38 @@ static void vfio_iommu_map_dirty_notify(IOMMUNotifier 
*n, IOMMUTLBEntry *iotlb)
                          container, iova,
                          iotlb->addr_mask + 1, ret);
         }
+        if (mr_has_discard_manager) {
+            /*
+             * Malicious VMs might trigger discarding of IOMMU-mapped memory.
+             * The pages will remain pinned inside vfio until unmapped,
+             * resulting in a higher memory consumption than expected. If 
memory
+             * would get populated again later, there would be an inconsistency
+             * between pages pinned by vfio and pages seen by QEMU. This is the
+             * case until unmapped from the IOMMU (e.g., during device reset).
+             *
+             * With malicious guests, we really only care about pinning more
+             * memory than expected. RLIMIT_MEMLOCK set for the user/process 
can
+             * never be exceeded and can be used to mitigate this problem.
+             */
+            warn_report_once(
+                "Using vfio with vIOMMUs and coordinated discarding of"
+                " RAM (e.g., virtio-mem) works, however, malicious"
+                " guests can trigger pinning of more memory than"
+                " intended via an IOMMU. It's possible to mitigate "
+                " by setting/adjusting RLIMIT_MEMLOCK.");
+        }
+    } else {
+        /*
+         * Malicious VMs can map memory into the IOMMU, which is expected
+         * to remain discarded. vfio will pin all pages, populating memory.
+         * Disallow that. vmstate priorities make sure any RamDiscardManager
+         * were already restored before IOMMUs are restored.
+         */
+        if (mr_has_discard_manager) {
+            error_report("iommu map to discarded memory (e.g., unplugged via"
+                         " virtio-mem): %" HWADDR_PRIx "",
+                         iotlb->translated_addr);
+        }
     }
     rcu_read_unlock();
 }
diff --git a/include/exec/memory.h b/include/exec/memory.h
index bfb1de8eea..ed8b1e8e0e 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -713,6 +713,10 @@ void 
ram_discard_manager_register_listener(RamDiscardManager *rdm,
 void ram_discard_manager_unregister_listener(RamDiscardManager *rdm,
                                              RamDiscardListener *rdl);
 
+bool memory_get_xlat_addr(IOMMUTLBEntry *iotlb, void **vaddr,
+                          ram_addr_t *ram_addr, bool *read_only,
+                          bool *mr_discard_populated);
+
 typedef struct CoalescedMemoryRange CoalescedMemoryRange;
 typedef struct MemoryRegionIoeventfd MemoryRegionIoeventfd;
 
diff --git a/softmmu/memory.c b/softmmu/memory.c
index 7ba2048836..b6ac5161e2 100644
--- a/softmmu/memory.c
+++ b/softmmu/memory.c
@@ -33,6 +33,7 @@
 #include "qemu/accel.h"
 #include "hw/boards.h"
 #include "migration/vmstate.h"
+#include "exec/address-spaces.h"
 
 //#define DEBUG_UNASSIGNED
 
@@ -2121,6 +2122,74 @@ void 
ram_discard_manager_unregister_listener(RamDiscardManager *rdm,
     rdmc->unregister_listener(rdm, rdl);
 }
 
+/* Called with rcu_read_lock held.  */
+bool memory_get_xlat_addr(IOMMUTLBEntry *iotlb, void **vaddr,
+                          ram_addr_t *ram_addr, bool *read_only,
+                          bool *mr_has_discard_manager)
+{
+    MemoryRegion *mr;
+    hwaddr xlat;
+    hwaddr len = iotlb->addr_mask + 1;
+    bool writable = iotlb->perm & IOMMU_WO;
+
+    if (mr_has_discard_manager) {
+        *mr_has_discard_manager = false;
+    }
+    /*
+     * The IOMMU TLB entry we have just covers translation through
+     * this IOMMU to its immediate target.  We need to translate
+     * it the rest of the way through to memory.
+     */
+    mr = address_space_translate(&address_space_memory, iotlb->translated_addr,
+                                 &xlat, &len, writable, 
MEMTXATTRS_UNSPECIFIED);
+    if (!memory_region_is_ram(mr)) {
+        error_report("iommu map to non memory area %" HWADDR_PRIx "", xlat);
+        return false;
+    } else if (memory_region_has_ram_discard_manager(mr)) {
+        RamDiscardManager *rdm = memory_region_get_ram_discard_manager(mr);
+        MemoryRegionSection tmp = {
+            .mr = mr,
+            .offset_within_region = xlat,
+            .size = int128_make64(len),
+        };
+        if (mr_has_discard_manager) {
+            *mr_has_discard_manager = true;
+        }
+        /*
+         * Malicious VMs can map memory into the IOMMU, which is expected
+         * to remain discarded. vfio will pin all pages, populating memory.
+         * Disallow that. vmstate priorities make sure any RamDiscardManager
+         * were already restored before IOMMUs are restored.
+         */
+        if (!ram_discard_manager_is_populated(rdm, &tmp)) {
+            return false;
+        }
+    }
+
+    /*
+     * Translation truncates length to the IOMMU page size,
+     * check that it did not truncate too much.
+     */
+    if (len & iotlb->addr_mask) {
+        error_report("iommu has granularity incompatible with target AS");
+        return false;
+    }
+
+    if (vaddr) {
+        *vaddr = memory_region_get_ram_ptr(mr) + xlat;
+    }
+
+    if (ram_addr) {
+        *ram_addr = memory_region_get_ram_addr(mr) + xlat;
+    }
+
+    if (read_only) {
+        *read_only = !writable || mr->readonly;
+    }
+
+    return true;
+}
+
 void memory_region_set_log(MemoryRegion *mr, bool log, unsigned client)
 {
     uint8_t mask = 1 << client;
-- 
2.34.3