- 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 <l...@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
