[PATCH v8 1/2] vfio: move implement of vfio_get_xlat_addr() to memory.c

[Cindy Lu <lulu@redhat.com>]

- Move the implement 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 function vfio_get_xlat_addr in vfio/common.c, and it will check
  whether the memory is backed by a discard manager. the device can
  have its own warning.

Signed-off-by: Cindy Lu <lulu@redhat.com>
---
 hw/vfio/common.c      | 101 +++++++++++-------------------------------
 include/exec/memory.h |   4 ++
 softmmu/memory.c      |  72 ++++++++++++++++++++++++++++++
 3 files changed, 102 insertions(+), 75 deletions(-)

diff --git a/hw/vfio/common.c b/hw/vfio/common.c
index ace9562a9b..5bfd55de86 100644
--- a/hw/vfio/common.c
+++ b/hw/vfio/common.c
@@ -578,86 +578,37 @@ static bool vfio_listener_skipped_section(MemoryRegionSection *section)
 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),
-        };
-
+    bool mr_has_discard_manager;
+    if (memory_get_xlat_addr(iotlb, vaddr, ram_addr, read_only,
+                             &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.
+         * if the mr has the discard_manager and the return value of
+         * memory_get_xlat_addr() is ture then we need to warn
          */
-        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;
+        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.");
         }
 
-        /*
-         * 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;
+        return true;
     }
-
-    if (ram_addr) {
-        *ram_addr = memory_region_get_ram_addr(mr) + xlat;
-    }
-
-    if (read_only) {
-        *read_only = !writable || mr->readonly;
-    }
-
-    return true;
+    return false;
 }
 
 static void vfio_iommu_map_notify(IOMMUNotifier *n, IOMMUTLBEntry *iotlb)
diff --git a/include/exec/memory.h b/include/exec/memory.h
index bfb1de8eea..d1e79c39dc 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_has_discard_manager);
+
 typedef struct CoalescedMemoryRange CoalescedMemoryRange;
 typedef struct MemoryRegionIoeventfd MemoryRegionIoeventfd;
 
diff --git a/softmmu/memory.c b/softmmu/memory.c
index 7ba2048836..bc0be3f62c 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 +2122,77 @@ 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)) {
+            error_report("iommu map to discarded memory (e.g., unplugged via"
+                         " virtio-mem): %" HWADDR_PRIx "",
+                         iotlb->translated_addr);
+            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