| Message ID | 20221030060106.1341675-2-lulu@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | vhost-vdpa: add support for vIOMMU | expand |
On Sun, 30 Oct 2022 14:01:05 +0800 Cindy Lu <lulu@redhat.com> wrote: > - 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 | 135 ++++++++++++++---------------------------- > include/exec/memory.h | 4 ++ > softmmu/memory.c | 72 ++++++++++++++++++++++ > 3 files changed, 122 insertions(+), 89 deletions(-) > > diff --git a/hw/vfio/common.c b/hw/vfio/common.c > index ace9562a9b..06ebbb82c7 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 +595,32 @@ static void vfio_iommu_map_notify(IOMMUNotifier *n, IOMMUTLBEntry *iotlb) > > if ((iotlb->perm & IOMMU_RW) != IOMMU_NONE) { > bool read_only; > + bool mr_has_discard_manager; > > - if (!vfio_get_xlat_addr(iotlb, &vaddr, NULL, &read_only)) { > + if (!memory_get_xlat_addr(iotlb, &vaddr, NULL, &read_only, > + &mr_has_discard_manager)) { > 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 +1285,7 @@ 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 +1296,9 @@ 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 +1307,26 @@ 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."); > + } This still needs a vfio wrapper to avoid the duplicate comment and warn_report_once. Thanks, Alex > } > rcu_read_unlock(); > } > 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;
On Sun, 30 Oct 2022 at 21:02, Alex Williamson <alex.williamson@redhat.com> wrote: > > On Sun, 30 Oct 2022 14:01:05 +0800 > Cindy Lu <lulu@redhat.com> wrote: > > > - 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 | 135 ++++++++++++++---------------------------- > > include/exec/memory.h | 4 ++ > > softmmu/memory.c | 72 ++++++++++++++++++++++ > > 3 files changed, 122 insertions(+), 89 deletions(-) > > > > diff --git a/hw/vfio/common.c b/hw/vfio/common.c > > index ace9562a9b..06ebbb82c7 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 +595,32 @@ static void vfio_iommu_map_notify(IOMMUNotifier *n, IOMMUTLBEntry *iotlb) > > > > if ((iotlb->perm & IOMMU_RW) != IOMMU_NONE) { > > bool read_only; > > + bool mr_has_discard_manager; > > > > - if (!vfio_get_xlat_addr(iotlb, &vaddr, NULL, &read_only)) { > > + if (!memory_get_xlat_addr(iotlb, &vaddr, NULL, &read_only, > > + &mr_has_discard_manager)) { > > 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 +1285,7 @@ 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 +1296,9 @@ 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 +1307,26 @@ 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."); > > + } > > This still needs a vfio wrapper to avoid the duplicate comment and > warn_report_once. Thanks, > > Alex > sure, will change this ,Thanks Alex Thanks Cindy > > > } > > rcu_read_unlock(); > > } > > 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; >
diff --git a/hw/vfio/common.c b/hw/vfio/common.c index ace9562a9b..06ebbb82c7 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 +595,32 @@ static void vfio_iommu_map_notify(IOMMUNotifier *n, IOMMUTLBEntry *iotlb) if ((iotlb->perm & IOMMU_RW) != IOMMU_NONE) { bool read_only; + bool mr_has_discard_manager; - if (!vfio_get_xlat_addr(iotlb, &vaddr, NULL, &read_only)) { + if (!memory_get_xlat_addr(iotlb, &vaddr, NULL, &read_only, + &mr_has_discard_manager)) { 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 +1285,7 @@ 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 +1296,9 @@ 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 +1307,26 @@ 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."); + } } rcu_read_unlock(); } 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;
- 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 | 135 ++++++++++++++---------------------------- include/exec/memory.h | 4 ++ softmmu/memory.c | 72 ++++++++++++++++++++++ 3 files changed, 122 insertions(+), 89 deletions(-)