From eba1f657cbb1b525e2b069626de655da21084e3e Mon Sep 17 00:00:00 2001 From: Steve Sistare Date: Tue, 10 Jun 2025 08:39:21 -0700 Subject: [PATCH] vfio/container: recover from unmap-all-vaddr failure MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit If there are multiple containers and unmap-all fails for some container, we need to remap vaddr for the other containers for which unmap-all succeeded. Recover by walking all address ranges of all containers to restore the vaddr for each. Do so by invoking the vfio listener callback, and passing a new "remap" flag that tells it to restore a mapping without re-allocating new userland data structures. Signed-off-by: Steve Sistare Reviewed-by: Cédric Le Goater Link: https://lore.kernel.org/qemu-devel/1749569991-25171-9-git-send-email-steven.sistare@oracle.com Signed-off-by: Cédric Le Goater --- hw/vfio/cpr-legacy.c | 91 +++++++++++++++++++++++++++ hw/vfio/listener.c | 19 +++++- include/hw/vfio/vfio-container-base.h | 3 + include/hw/vfio/vfio-cpr.h | 10 +++ 4 files changed, 122 insertions(+), 1 deletion(-) diff --git a/hw/vfio/cpr-legacy.c b/hw/vfio/cpr-legacy.c index 2fd8348c7c..a84c3247b7 100644 --- a/hw/vfio/cpr-legacy.c +++ b/hw/vfio/cpr-legacy.c @@ -29,6 +29,7 @@ static bool vfio_dma_unmap_vaddr_all(VFIOContainer *container, Error **errp) error_setg_errno(errp, errno, "vfio_dma_unmap_vaddr_all"); return false; } + container->cpr.vaddr_unmapped = true; return true; } @@ -59,6 +60,14 @@ static int vfio_legacy_cpr_dma_map(const VFIOContainerBase *bcontainer, return 0; } +static void vfio_region_remap(MemoryListener *listener, + MemoryRegionSection *section) +{ + VFIOContainer *container = container_of(listener, VFIOContainer, + cpr.remap_listener); + vfio_container_region_add(&container->bcontainer, section, true); +} + static bool vfio_cpr_supported(VFIOContainer *container, Error **errp) { if (!ioctl(container->fd, VFIO_CHECK_EXTENSION, VFIO_UPDATE_VADDR)) { @@ -120,6 +129,40 @@ static const VMStateDescription vfio_container_vmstate = { } }; +static int vfio_cpr_fail_notifier(NotifierWithReturn *notifier, + MigrationEvent *e, Error **errp) +{ + VFIOContainer *container = + container_of(notifier, VFIOContainer, cpr.transfer_notifier); + VFIOContainerBase *bcontainer = &container->bcontainer; + + if (e->type != MIG_EVENT_PRECOPY_FAILED) { + return 0; + } + + if (container->cpr.vaddr_unmapped) { + /* + * Force a call to vfio_region_remap for each mapped section by + * temporarily registering a listener, and temporarily diverting + * dma_map to vfio_legacy_cpr_dma_map. The latter restores vaddr. + */ + + VFIOIOMMUClass *vioc = VFIO_IOMMU_GET_CLASS(bcontainer); + vioc->dma_map = vfio_legacy_cpr_dma_map; + + container->cpr.remap_listener = (MemoryListener) { + .name = "vfio cpr recover", + .region_add = vfio_region_remap + }; + memory_listener_register(&container->cpr.remap_listener, + bcontainer->space->as); + memory_listener_unregister(&container->cpr.remap_listener); + container->cpr.vaddr_unmapped = false; + vioc->dma_map = container->cpr.saved_dma_map; + } + return 0; +} + bool vfio_legacy_cpr_register_container(VFIOContainer *container, Error **errp) { VFIOContainerBase *bcontainer = &container->bcontainer; @@ -142,6 +185,10 @@ bool vfio_legacy_cpr_register_container(VFIOContainer *container, Error **errp) container->cpr.saved_dma_map = vioc->dma_map; vioc->dma_map = vfio_legacy_cpr_dma_map; } + + migration_add_notifier_mode(&container->cpr.transfer_notifier, + vfio_cpr_fail_notifier, + MIG_MODE_CPR_TRANSFER); return true; } @@ -152,6 +199,50 @@ void vfio_legacy_cpr_unregister_container(VFIOContainer *container) migration_remove_notifier(&bcontainer->cpr_reboot_notifier); migrate_del_blocker(&container->cpr.blocker); vmstate_unregister(NULL, &vfio_container_vmstate, container); + migration_remove_notifier(&container->cpr.transfer_notifier); +} + +/* + * In old QEMU, VFIO_DMA_UNMAP_FLAG_VADDR may fail on some mapping after + * succeeding for others, so the latter have lost their vaddr. Call this + * to restore vaddr for a section with a giommu. + * + * The giommu already exists. Find it and replay it, which calls + * vfio_legacy_cpr_dma_map further down the stack. + */ +void vfio_cpr_giommu_remap(VFIOContainerBase *bcontainer, + MemoryRegionSection *section) +{ + VFIOGuestIOMMU *giommu = NULL; + hwaddr as_offset = section->offset_within_address_space; + hwaddr iommu_offset = as_offset - section->offset_within_region; + + QLIST_FOREACH(giommu, &bcontainer->giommu_list, giommu_next) { + if (giommu->iommu_mr == IOMMU_MEMORY_REGION(section->mr) && + giommu->iommu_offset == iommu_offset) { + break; + } + } + g_assert(giommu); + memory_region_iommu_replay(giommu->iommu_mr, &giommu->n); +} + +/* + * In old QEMU, VFIO_DMA_UNMAP_FLAG_VADDR may fail on some mapping after + * succeeding for others, so the latter have lost their vaddr. Call this + * to restore vaddr for a section with a RamDiscardManager. + * + * The ram discard listener already exists. Call its populate function + * directly, which calls vfio_legacy_cpr_dma_map. + */ +bool vfio_cpr_ram_discard_register_listener(VFIOContainerBase *bcontainer, + MemoryRegionSection *section) +{ + VFIORamDiscardListener *vrdl = + vfio_find_ram_discard_listener(bcontainer, section); + + g_assert(vrdl); + return vrdl->listener.notify_populate(&vrdl->listener, section) == 0; } int vfio_cpr_group_get_device_fd(int d, const char *name) diff --git a/hw/vfio/listener.c b/hw/vfio/listener.c index 735b5f21b7..f498e23a93 100644 --- a/hw/vfio/listener.c +++ b/hw/vfio/listener.c @@ -481,6 +481,13 @@ static void vfio_listener_region_add(MemoryListener *listener, { VFIOContainerBase *bcontainer = container_of(listener, VFIOContainerBase, listener); + vfio_container_region_add(bcontainer, section, false); +} + +void vfio_container_region_add(VFIOContainerBase *bcontainer, + MemoryRegionSection *section, + bool cpr_remap) +{ hwaddr iova, end; Int128 llend, llsize; void *vaddr; @@ -516,6 +523,11 @@ static void vfio_listener_region_add(MemoryListener *listener, int iommu_idx; trace_vfio_listener_region_add_iommu(section->mr->name, iova, end); + + if (cpr_remap) { + vfio_cpr_giommu_remap(bcontainer, section); + } + /* * FIXME: For VFIO iommu types which have KVM acceleration to * avoid bouncing all map/unmaps through qemu this way, this @@ -558,7 +570,12 @@ static void vfio_listener_region_add(MemoryListener *listener, * about changes. */ if (memory_region_has_ram_discard_manager(section->mr)) { - vfio_ram_discard_register_listener(bcontainer, section); + if (!cpr_remap) { + vfio_ram_discard_register_listener(bcontainer, section); + } else if (!vfio_cpr_ram_discard_register_listener(bcontainer, + section)) { + goto fail; + } return; } diff --git a/include/hw/vfio/vfio-container-base.h b/include/hw/vfio/vfio-container-base.h index 9d37f86115..f0232654ee 100644 --- a/include/hw/vfio/vfio-container-base.h +++ b/include/hw/vfio/vfio-container-base.h @@ -256,4 +256,7 @@ struct VFIOIOMMUClass { VFIORamDiscardListener *vfio_find_ram_discard_listener( VFIOContainerBase *bcontainer, MemoryRegionSection *section); +void vfio_container_region_add(VFIOContainerBase *bcontainer, + MemoryRegionSection *section, bool cpr_remap); + #endif /* HW_VFIO_VFIO_CONTAINER_BASE_H */ diff --git a/include/hw/vfio/vfio-cpr.h b/include/hw/vfio/vfio-cpr.h index b83dd42751..56ede049ad 100644 --- a/include/hw/vfio/vfio-cpr.h +++ b/include/hw/vfio/vfio-cpr.h @@ -10,6 +10,7 @@ #define HW_VFIO_VFIO_CPR_H #include "migration/misc.h" +#include "system/memory.h" struct VFIOContainer; struct VFIOContainerBase; @@ -17,6 +18,9 @@ struct VFIOGroup; typedef struct VFIOContainerCPR { Error *blocker; + bool vaddr_unmapped; + NotifierWithReturn transfer_notifier; + MemoryListener remap_listener; int (*saved_dma_map)(const struct VFIOContainerBase *bcontainer, hwaddr iova, ram_addr_t size, void *vaddr, bool readonly, MemoryRegion *mr); @@ -42,4 +46,10 @@ int vfio_cpr_group_get_device_fd(int d, const char *name); bool vfio_cpr_container_match(struct VFIOContainer *container, struct VFIOGroup *group, int fd); +void vfio_cpr_giommu_remap(struct VFIOContainerBase *bcontainer, + MemoryRegionSection *section); + +bool vfio_cpr_ram_discard_register_listener( + struct VFIOContainerBase *bcontainer, MemoryRegionSection *section); + #endif /* HW_VFIO_VFIO_CPR_H */ -- 2.39.5