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bh=+hqbNHKp7nfp8Ablsh+VUxEE2OoZCl4kTkhN5BtMfzU=; b=COHLBEvtyKWpklYKH3NbxG2sk4V31c9g+LwcZBjayDmTU6v19hD4gtXa2zRM1y/impQl26 RPHIfRGLr+IPYCvRqN94hWpnd9BrTeZY0dvhkQ6ToxF7h0DaDK4Sj84xGbhGHKsKus5T83 A7fpcqswwU7A+H98pVmw93LTDEHg1Ic= X-MC-Unique: hJ--do0-OrGK_6SAMkBmZQ-1 From: Cindy Lu To: lulu@redhat.com, alex.williamson@redhat.com, jasowang@redhat.com, mst@redhat.com, pbonzini@redhat.com, peterx@redhat.com, david@redhat.com, f4bug@amsat.org, sgarzare@redhat.com Cc: qemu-devel@nongnu.org Subject: [PATCH v6 1/2] vfio: move function vfio_get_xlat_addr() to memory.c Date: Sun, 30 Oct 2022 14:01:05 +0800 Message-Id: <20221030060106.1341675-2-lulu@redhat.com> In-Reply-To: <20221030060106.1341675-1-lulu@redhat.com> References: <20221030060106.1341675-1-lulu@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.1 on 10.11.54.4 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.129.124; envelope-from=lulu@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -25 X-Spam_score: -2.6 X-Spam_bar: -- X-Spam_report: (-2.6 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.516, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Qemu-devel" Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1667109758218100001 - Move the function vfio_get_xlat_addr to softmmu/memory.c, and =C2=A0 change the name to memory_get_xlat_addr(). So we can use this =C2=A0 function on other devices, such as vDPA device. - Add a new bool arg in this function, which shows whether the memory is =C2=A0 backed by a discard manager. So the device can have its own warning. Signed-off-by: Cindy Lu --- 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(MemoryRegion= Section *section) section->offset_within_address_space & (1ULL << 63); } =20 -/* 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 =3D iotlb->addr_mask + 1; - bool writable =3D 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 =3D 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 =3D memory_region_get_ram_discard_manager(m= r); - MemoryRegionSection tmp =3D { - .mr =3D mr, - .offset_within_region =3D xlat, - .size =3D 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 RamDiscardManag= er - * 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 v= ia" - " 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 m= emory - * than expected. RLIMIT_MEMLOCK set for the user/process can neve= r be - * exceeded and can be used to mitigate this problem. - */ - warn_report_once("Using vfio with vIOMMUs and coordinated discardi= ng of" - " RAM (e.g., virtio-mem) works, however, maliciou= s" - " guests can trigger pinning of more memory than" - " intended via an IOMMU. It's possible to mitigat= e " - " 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 =3D memory_region_get_ram_ptr(mr) + xlat; - } - - if (ram_addr) { - *ram_addr =3D memory_region_get_ram_addr(mr) + xlat; - } - - if (read_only) { - *read_only =3D !writable || mr->readonly; - } - - return true; -} - static void vfio_iommu_map_notify(IOMMUNotifier *n, IOMMUTLBEntry *iotlb) { VFIOGuestIOMMU *giommu =3D container_of(n, VFIOGuestIOMMU, n); @@ -681,10 +595,32 @@ static void vfio_iommu_map_notify(IOMMUNotifier *n, I= OMMUTLBEntry *iotlb) =20 if ((iotlb->perm & IOMMU_RW) !=3D IOMMU_NONE) { bool read_only; + bool mr_has_discard_manager; =20 - 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 memo= ry. + * 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 inconsis= tency + * between pages pinned by vfio and pages seen by QEMU. This i= s the + * case until unmapped from the IOMMU (e.g., during device res= et). + * + * With malicious guests, we really only care about pinning mo= re + * memory than expected. RLIMIT_MEMLOCK set for the user/proce= ss 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 =3D giommu->container; hwaddr iova =3D iotlb->iova + giommu->iommu_offset; ram_addr_t translated_addr; + bool mr_has_discard_manager; =20 trace_vfio_iommu_map_dirty_notify(iova, iova + iotlb->addr_mask); =20 @@ -1359,9 +1296,9 @@ static void vfio_iommu_map_dirty_notify(IOMMUNotifier= *n, IOMMUTLBEntry *iotlb) } =20 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 =3D 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(IOMMUNotifie= r *n, IOMMUTLBEntry *iotlb) container, iova, iotlb->addr_mask + 1, ret); } + if (mr_has_discard_manager) { + /* + * Malicious VMs might trigger discarding of IOMMU-mapped memo= ry. + * 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 inconsis= tency + * between pages pinned by vfio and pages seen by QEMU. This i= s the + * case until unmapped from the IOMMU (e.g., during device res= et). + * + * With malicious guests, we really only care about pinning mo= re + * memory than expected. RLIMIT_MEMLOCK set for the user/proce= ss 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(RamDiscardM= anager *rdm, void ram_discard_manager_unregister_listener(RamDiscardManager *rdm, RamDiscardListener *rdl); =20 +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; =20 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" =20 //#define DEBUG_UNASSIGNED =20 @@ -2121,6 +2122,77 @@ void ram_discard_manager_unregister_listener(RamDisc= ardManager *rdm, rdmc->unregister_listener(rdm, rdl); } =20 +/* 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 =3D iotlb->addr_mask + 1; + bool writable =3D iotlb->perm & IOMMU_WO; + + if (mr_has_discard_manager) { + *mr_has_discard_manager =3D 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 =3D address_space_translate(&address_space_memory, iotlb->translate= d_addr, + &xlat, &len, writable, MEMTXATTRS_UNSPECI= FIED); + 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 =3D memory_region_get_ram_discard_manager(m= r); + MemoryRegionSection tmp =3D { + .mr =3D mr, + .offset_within_region =3D xlat, + .size =3D int128_make64(len), + }; + if (mr_has_discard_manager) { + *mr_has_discard_manager =3D 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 RamDiscardManag= er + * 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 v= ia" + " 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 =3D memory_region_get_ram_ptr(mr) + xlat; + } + + if (ram_addr) { + *ram_addr =3D memory_region_get_ram_addr(mr) + xlat; + } + + if (read_only) { + *read_only =3D !writable || mr->readonly; + } + + return true; +} + void memory_region_set_log(MemoryRegion *mr, bool log, unsigned client) { uint8_t mask =3D 1 << client; --=20 2.34.3