From 082851a3af1450fa714e9a0a3ca7cb4b9dbd8855 Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Thu, 29 Apr 2021 13:26:59 +0200 Subject: util: vfio-helpers: Factor out and fix processing of existing ram blocks Factor it out into common code when a new notifier is registered, just as done with the memory region notifier. This keeps logic about how to process existing ram blocks at a central place. Just like when adding a new ram block, we have to register the max_length. Ram blocks are only "fake resized". All memory (max_length) is mapped. Print the warning from inside qemu_vfio_ram_block_added(). Reviewed-by: Peter Xu Signed-off-by: David Hildenbrand Message-Id: <20210429112708.12291-2-david@redhat.com> Signed-off-by: Dr. David Alan Gilbert --- include/exec/cpu-common.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/exec') diff --git a/include/exec/cpu-common.h b/include/exec/cpu-common.h index 5a0a2d93e0..ccabed4003 100644 --- a/include/exec/cpu-common.h +++ b/include/exec/cpu-common.h @@ -57,6 +57,7 @@ const char *qemu_ram_get_idstr(RAMBlock *rb); void *qemu_ram_get_host_addr(RAMBlock *rb); ram_addr_t qemu_ram_get_offset(RAMBlock *rb); ram_addr_t qemu_ram_get_used_length(RAMBlock *rb); +ram_addr_t qemu_ram_get_max_length(RAMBlock *rb); bool qemu_ram_is_shared(RAMBlock *rb); bool qemu_ram_is_uf_zeroable(RAMBlock *rb); void qemu_ram_set_uf_zeroable(RAMBlock *rb); -- cgit v1.2.3-55-g7522 From 8f44304c76036ac8544468c9306c5b30d1fdd201 Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Thu, 29 Apr 2021 13:27:00 +0200 Subject: numa: Teach ram block notifiers about resizeable ram blocks Ram block notifiers are currently not aware of resizes. To properly handle resizes during migration, we want to teach ram block notifiers about resizeable ram. Introduce the basic infrastructure but keep using max_size in the existing notifiers. Supply the max_size when adding and removing ram blocks. Also, notify on resizes. Acked-by: Paul Durrant Reviewed-by: Peter Xu Cc: xen-devel@lists.xenproject.org Cc: haxm-team@intel.com Cc: Paul Durrant Cc: Stefano Stabellini Cc: Anthony Perard Cc: Wenchao Wang Cc: Colin Xu Signed-off-by: David Hildenbrand Message-Id: <20210429112708.12291-3-david@redhat.com> Signed-off-by: Dr. David Alan Gilbert --- hw/core/numa.c | 22 +++++++++++++++++----- hw/i386/xen/xen-mapcache.c | 7 ++++--- include/exec/ramlist.h | 13 +++++++++---- softmmu/physmem.c | 12 ++++++++++-- target/i386/hax/hax-mem.c | 5 +++-- target/i386/sev.c | 18 ++++++++++-------- util/vfio-helpers.c | 16 ++++++++-------- 7 files changed, 61 insertions(+), 32 deletions(-) (limited to 'include/exec') diff --git a/hw/core/numa.c b/hw/core/numa.c index 134ebc2b72..4c58b2348d 100644 --- a/hw/core/numa.c +++ b/hw/core/numa.c @@ -805,11 +805,12 @@ void query_numa_node_mem(NumaNodeMem node_mem[], MachineState *ms) static int ram_block_notify_add_single(RAMBlock *rb, void *opaque) { const ram_addr_t max_size = qemu_ram_get_max_length(rb); + const ram_addr_t size = qemu_ram_get_used_length(rb); void *host = qemu_ram_get_host_addr(rb); RAMBlockNotifier *notifier = opaque; if (host) { - notifier->ram_block_added(notifier, host, max_size); + notifier->ram_block_added(notifier, host, size, max_size); } return 0; } @@ -826,20 +827,31 @@ void ram_block_notifier_remove(RAMBlockNotifier *n) QLIST_REMOVE(n, next); } -void ram_block_notify_add(void *host, size_t size) +void ram_block_notify_add(void *host, size_t size, size_t max_size) { RAMBlockNotifier *notifier; QLIST_FOREACH(notifier, &ram_list.ramblock_notifiers, next) { - notifier->ram_block_added(notifier, host, size); + notifier->ram_block_added(notifier, host, size, max_size); } } -void ram_block_notify_remove(void *host, size_t size) +void ram_block_notify_remove(void *host, size_t size, size_t max_size) { RAMBlockNotifier *notifier; QLIST_FOREACH(notifier, &ram_list.ramblock_notifiers, next) { - notifier->ram_block_removed(notifier, host, size); + notifier->ram_block_removed(notifier, host, size, max_size); + } +} + +void ram_block_notify_resize(void *host, size_t old_size, size_t new_size) +{ + RAMBlockNotifier *notifier; + + QLIST_FOREACH(notifier, &ram_list.ramblock_notifiers, next) { + if (notifier->ram_block_resized) { + notifier->ram_block_resized(notifier, host, old_size, new_size); + } } } diff --git a/hw/i386/xen/xen-mapcache.c b/hw/i386/xen/xen-mapcache.c index e82b7dcdd2..bd47c3d672 100644 --- a/hw/i386/xen/xen-mapcache.c +++ b/hw/i386/xen/xen-mapcache.c @@ -169,7 +169,8 @@ static void xen_remap_bucket(MapCacheEntry *entry, if (entry->vaddr_base != NULL) { if (!(entry->flags & XEN_MAPCACHE_ENTRY_DUMMY)) { - ram_block_notify_remove(entry->vaddr_base, entry->size); + ram_block_notify_remove(entry->vaddr_base, entry->size, + entry->size); } /* @@ -224,7 +225,7 @@ static void xen_remap_bucket(MapCacheEntry *entry, } if (!(entry->flags & XEN_MAPCACHE_ENTRY_DUMMY)) { - ram_block_notify_add(vaddr_base, size); + ram_block_notify_add(vaddr_base, size, size); } entry->vaddr_base = vaddr_base; @@ -465,7 +466,7 @@ static void xen_invalidate_map_cache_entry_unlocked(uint8_t *buffer) } pentry->next = entry->next; - ram_block_notify_remove(entry->vaddr_base, entry->size); + ram_block_notify_remove(entry->vaddr_base, entry->size, entry->size); if (munmap(entry->vaddr_base, entry->size) != 0) { perror("unmap fails"); exit(-1); diff --git a/include/exec/ramlist.h b/include/exec/ramlist.h index 26704aa3b0..ece6497ee2 100644 --- a/include/exec/ramlist.h +++ b/include/exec/ramlist.h @@ -65,15 +65,20 @@ void qemu_mutex_lock_ramlist(void); void qemu_mutex_unlock_ramlist(void); struct RAMBlockNotifier { - void (*ram_block_added)(RAMBlockNotifier *n, void *host, size_t size); - void (*ram_block_removed)(RAMBlockNotifier *n, void *host, size_t size); + void (*ram_block_added)(RAMBlockNotifier *n, void *host, size_t size, + size_t max_size); + void (*ram_block_removed)(RAMBlockNotifier *n, void *host, size_t size, + size_t max_size); + void (*ram_block_resized)(RAMBlockNotifier *n, void *host, size_t old_size, + size_t new_size); QLIST_ENTRY(RAMBlockNotifier) next; }; void ram_block_notifier_add(RAMBlockNotifier *n); void ram_block_notifier_remove(RAMBlockNotifier *n); -void ram_block_notify_add(void *host, size_t size); -void ram_block_notify_remove(void *host, size_t size); +void ram_block_notify_add(void *host, size_t size, size_t max_size); +void ram_block_notify_remove(void *host, size_t size, size_t max_size); +void ram_block_notify_resize(void *host, size_t old_size, size_t new_size); void ram_block_dump(Monitor *mon); diff --git a/softmmu/physmem.c b/softmmu/physmem.c index 0a05533ed0..81ec3b85b9 100644 --- a/softmmu/physmem.c +++ b/softmmu/physmem.c @@ -1807,6 +1807,7 @@ static int memory_try_enable_merging(void *addr, size_t len) */ int qemu_ram_resize(RAMBlock *block, ram_addr_t newsize, Error **errp) { + const ram_addr_t oldsize = block->used_length; const ram_addr_t unaligned_size = newsize; assert(block); @@ -1843,6 +1844,11 @@ int qemu_ram_resize(RAMBlock *block, ram_addr_t newsize, Error **errp) return -EINVAL; } + /* Notify before modifying the ram block and touching the bitmaps. */ + if (block->host) { + ram_block_notify_resize(block->host, oldsize, newsize); + } + cpu_physical_memory_clear_dirty_range(block->offset, block->used_length); block->used_length = newsize; cpu_physical_memory_set_dirty_range(block->offset, block->used_length, @@ -2010,7 +2016,8 @@ static void ram_block_add(RAMBlock *new_block, Error **errp, bool shared) qemu_madvise(new_block->host, new_block->max_length, QEMU_MADV_DONTFORK); } - ram_block_notify_add(new_block->host, new_block->max_length); + ram_block_notify_add(new_block->host, new_block->used_length, + new_block->max_length); } } @@ -2189,7 +2196,8 @@ void qemu_ram_free(RAMBlock *block) } if (block->host) { - ram_block_notify_remove(block->host, block->max_length); + ram_block_notify_remove(block->host, block->used_length, + block->max_length); } qemu_mutex_lock_ramlist(); diff --git a/target/i386/hax/hax-mem.c b/target/i386/hax/hax-mem.c index 35495f5e82..8d44edbffd 100644 --- a/target/i386/hax/hax-mem.c +++ b/target/i386/hax/hax-mem.c @@ -293,7 +293,8 @@ static MemoryListener hax_memory_listener = { .priority = 10, }; -static void hax_ram_block_added(RAMBlockNotifier *n, void *host, size_t size) +static void hax_ram_block_added(RAMBlockNotifier *n, void *host, size_t size, + size_t max_size) { /* * We must register each RAM block with the HAXM kernel module, or @@ -304,7 +305,7 @@ static void hax_ram_block_added(RAMBlockNotifier *n, void *host, size_t size) * host physical pages for the RAM block as part of this registration * process, hence the name hax_populate_ram(). */ - if (hax_populate_ram((uint64_t)(uintptr_t)host, size) < 0) { + if (hax_populate_ram((uint64_t)(uintptr_t)host, max_size) < 0) { fprintf(stderr, "HAX failed to populate RAM\n"); abort(); } diff --git a/target/i386/sev.c b/target/i386/sev.c index 9a43be11cb..41f7800b5f 100644 --- a/target/i386/sev.c +++ b/target/i386/sev.c @@ -180,7 +180,8 @@ sev_set_guest_state(SevGuestState *sev, SevState new_state) } static void -sev_ram_block_added(RAMBlockNotifier *n, void *host, size_t size) +sev_ram_block_added(RAMBlockNotifier *n, void *host, size_t size, + size_t max_size) { int r; struct kvm_enc_region range; @@ -197,19 +198,20 @@ sev_ram_block_added(RAMBlockNotifier *n, void *host, size_t size) } range.addr = (__u64)(unsigned long)host; - range.size = size; + range.size = max_size; - trace_kvm_memcrypt_register_region(host, size); + trace_kvm_memcrypt_register_region(host, max_size); r = kvm_vm_ioctl(kvm_state, KVM_MEMORY_ENCRYPT_REG_REGION, &range); if (r) { error_report("%s: failed to register region (%p+%#zx) error '%s'", - __func__, host, size, strerror(errno)); + __func__, host, max_size, strerror(errno)); exit(1); } } static void -sev_ram_block_removed(RAMBlockNotifier *n, void *host, size_t size) +sev_ram_block_removed(RAMBlockNotifier *n, void *host, size_t size, + size_t max_size) { int r; struct kvm_enc_region range; @@ -226,13 +228,13 @@ sev_ram_block_removed(RAMBlockNotifier *n, void *host, size_t size) } range.addr = (__u64)(unsigned long)host; - range.size = size; + range.size = max_size; - trace_kvm_memcrypt_unregister_region(host, size); + trace_kvm_memcrypt_unregister_region(host, max_size); r = kvm_vm_ioctl(kvm_state, KVM_MEMORY_ENCRYPT_UNREG_REGION, &range); if (r) { error_report("%s: failed to unregister region (%p+%#zx)", - __func__, host, size); + __func__, host, max_size); } } diff --git a/util/vfio-helpers.c b/util/vfio-helpers.c index 92b9565797..911115b86e 100644 --- a/util/vfio-helpers.c +++ b/util/vfio-helpers.c @@ -459,26 +459,26 @@ fail_container: return ret; } -static void qemu_vfio_ram_block_added(RAMBlockNotifier *n, - void *host, size_t size) +static void qemu_vfio_ram_block_added(RAMBlockNotifier *n, void *host, + size_t size, size_t max_size) { QEMUVFIOState *s = container_of(n, QEMUVFIOState, ram_notifier); int ret; - trace_qemu_vfio_ram_block_added(s, host, size); - ret = qemu_vfio_dma_map(s, host, size, false, NULL); + trace_qemu_vfio_ram_block_added(s, host, max_size); + ret = qemu_vfio_dma_map(s, host, max_size, false, NULL); if (ret) { - error_report("qemu_vfio_dma_map(%p, %zu) failed: %s", host, size, + error_report("qemu_vfio_dma_map(%p, %zu) failed: %s", host, max_size, strerror(-ret)); } } -static void qemu_vfio_ram_block_removed(RAMBlockNotifier *n, - void *host, size_t size) +static void qemu_vfio_ram_block_removed(RAMBlockNotifier *n, void *host, + size_t size, size_t max_size) { QEMUVFIOState *s = container_of(n, QEMUVFIOState, ram_notifier); if (host) { - trace_qemu_vfio_ram_block_removed(s, host, size); + trace_qemu_vfio_ram_block_removed(s, host, max_size); qemu_vfio_dma_unmap(s, host); } } -- cgit v1.2.3-55-g7522 From c7c0e72408df5e7821c0e995122fb2fe0ac001f1 Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Thu, 29 Apr 2021 13:27:02 +0200 Subject: migration/ram: Handle RAM block resizes during precopy Resizing while migrating is dangerous and does not work as expected. The whole migration code works on the usable_length of ram blocks and does not expect this to change at random points in time. In the case of precopy, the ram block size must not change on the source, after syncing the RAM block list in ram_save_setup(), so as long as the guest is still running on the source. Resizing can be trigger *after* (but not during) a reset in ACPI code by the guest - hw/arm/virt-acpi-build.c:acpi_ram_update() - hw/i386/acpi-build.c:acpi_ram_update() Use the ram block notifier to get notified about resizes. Let's simply cancel migration and indicate the reason. We'll continue running on the source. No harm done. Update the documentation. Postcopy will be handled separately. Reviewed-by: Peter Xu Signed-off-by: David Hildenbrand Message-Id: <20210429112708.12291-5-david@redhat.com> Signed-off-by: Dr. David Alan Gilbert Manual merge --- include/exec/memory.h | 10 ++++++---- migration/migration.c | 9 +++++++-- migration/migration.h | 1 + migration/ram.c | 30 ++++++++++++++++++++++++++++++ softmmu/physmem.c | 5 +++-- 5 files changed, 47 insertions(+), 8 deletions(-) (limited to 'include/exec') diff --git a/include/exec/memory.h b/include/exec/memory.h index 5728a681b2..c8b9088924 100644 --- a/include/exec/memory.h +++ b/include/exec/memory.h @@ -131,7 +131,7 @@ typedef struct IOMMUTLBEvent { #define RAM_SHARED (1 << 1) /* Only a portion of RAM (used_length) is actually used, and migrated. - * This used_length size can change across reboots. + * Resizing RAM while migrating can result in the migration being canceled. */ #define RAM_RESIZEABLE (1 << 2) @@ -955,7 +955,9 @@ void memory_region_init_ram_shared_nomigrate(MemoryRegion *mr, * RAM. Accesses into the region will * modify memory directly. Only an initial * portion of this RAM is actually used. - * The used size can change across reboots. + * Changing the size while migrating + * can result in the migration being + * canceled. * * @mr: the #MemoryRegion to be initialized. * @owner: the object that tracks the region's reference count @@ -1586,8 +1588,8 @@ void *memory_region_get_ram_ptr(MemoryRegion *mr); /* memory_region_ram_resize: Resize a RAM region. * - * Only legal before guest might have detected the memory size: e.g. on - * incoming migration, or right after reset. + * Resizing RAM while migrating can result in the migration being canceled. + * Care has to be taken if the guest might have already detected the memory. * * @mr: a memory region created with @memory_region_init_resizeable_ram. * @newsize: the new size the region diff --git a/migration/migration.c b/migration/migration.c index fdadee290e..4698b47442 100644 --- a/migration/migration.c +++ b/migration/migration.c @@ -223,13 +223,18 @@ void migration_object_init(void) dirty_bitmap_mig_init(); } +void migration_cancel(void) +{ + migrate_fd_cancel(current_migration); +} + void migration_shutdown(void) { /* * Cancel the current migration - that will (eventually) * stop the migration using this structure */ - migrate_fd_cancel(current_migration); + migration_cancel(); object_unref(OBJECT(current_migration)); /* @@ -2307,7 +2312,7 @@ void qmp_migrate(const char *uri, bool has_blk, bool blk, void qmp_migrate_cancel(Error **errp) { - migrate_fd_cancel(migrate_get_current()); + migration_cancel(); } void qmp_migrate_continue(MigrationStatus state, Error **errp) diff --git a/migration/migration.h b/migration/migration.h index db6708326b..f7b388d718 100644 --- a/migration/migration.h +++ b/migration/migration.h @@ -375,5 +375,6 @@ int foreach_not_ignored_block(RAMBlockIterFunc func, void *opaque); void migration_make_urgent_request(void); void migration_consume_urgent_request(void); bool migration_rate_limit(void); +void migration_cancel(void); #endif diff --git a/migration/ram.c b/migration/ram.c index bb52bd97db..77922c445e 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -4096,8 +4096,38 @@ static SaveVMHandlers savevm_ram_handlers = { .resume_prepare = ram_resume_prepare, }; +static void ram_mig_ram_block_resized(RAMBlockNotifier *n, void *host, + size_t old_size, size_t new_size) +{ + ram_addr_t offset; + RAMBlock *rb = qemu_ram_block_from_host(host, false, &offset); + Error *err = NULL; + + if (ramblock_is_ignored(rb)) { + return; + } + + if (!migration_is_idle()) { + /* + * Precopy code on the source cannot deal with the size of RAM blocks + * changing at random points in time - especially after sending the + * RAM block sizes in the migration stream, they must no longer change. + * Abort and indicate a proper reason. + */ + error_setg(&err, "RAM block '%s' resized during precopy.", rb->idstr); + migrate_set_error(migrate_get_current(), err); + error_free(err); + migration_cancel(); + } +} + +static RAMBlockNotifier ram_mig_ram_notifier = { + .ram_block_resized = ram_mig_ram_block_resized, +}; + void ram_mig_init(void) { qemu_mutex_init(&XBZRLE.lock); register_savevm_live("ram", 0, 4, &savevm_ram_handlers, &ram_state); + ram_block_notifier_add(&ram_mig_ram_notifier); } diff --git a/softmmu/physmem.c b/softmmu/physmem.c index 81ec3b85b9..813a3efe8e 100644 --- a/softmmu/physmem.c +++ b/softmmu/physmem.c @@ -1798,8 +1798,9 @@ static int memory_try_enable_merging(void *addr, size_t len) return qemu_madvise(addr, len, QEMU_MADV_MERGEABLE); } -/* Only legal before guest might have detected the memory size: e.g. on - * incoming migration, or right after reset. +/* + * Resizing RAM while migrating can result in the migration being canceled. + * Care has to be taken if the guest might have already detected the memory. * * As memory core doesn't know how is memory accessed, it is up to * resize callback to update device state and/or add assertions to detect -- cgit v1.2.3-55-g7522 From 898ba906ccb85ba17d65e64a31cc13128803ef86 Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Thu, 29 Apr 2021 13:27:06 +0200 Subject: migration/ram: Handle RAM block resizes during postcopy Resizing while migrating is dangerous and does not work as expected. The whole migration code works with the usable_length of a ram block and does not expect this value to change at random points in time. In the case of postcopy, relying on used_length is racy as soon as the guest is running. Also, when used_length changes we might leave the uffd handler registered for some memory regions, reject valid pages when migrating and fail when sending the recv bitmap to the source. Resizing can be trigger *after* (but not during) a reset in ACPI code by the guest - hw/arm/virt-acpi-build.c:acpi_ram_update() - hw/i386/acpi-build.c:acpi_ram_update() Let's remember the original used_length in a separate variable and use it in relevant postcopy code. Make sure to update it when we resize during precopy, when synchronizing the RAM block sizes with the source. Reviewed-by: Peter Xu Reviewed-by: Dr. David Alan Gilbert Signed-off-by: David Hildenbrand Message-Id: <20210429112708.12291-9-david@redhat.com> Signed-off-by: Dr. David Alan Gilbert --- include/exec/ramblock.h | 10 ++++++++++ migration/postcopy-ram.c | 15 ++++++++++++--- migration/ram.c | 11 +++++++++-- 3 files changed, 31 insertions(+), 5 deletions(-) (limited to 'include/exec') diff --git a/include/exec/ramblock.h b/include/exec/ramblock.h index 07d50864d8..664701b759 100644 --- a/include/exec/ramblock.h +++ b/include/exec/ramblock.h @@ -59,6 +59,16 @@ struct RAMBlock { */ unsigned long *clear_bmap; uint8_t clear_bmap_shift; + + /* + * RAM block length that corresponds to the used_length on the migration + * source (after RAM block sizes were synchronized). Especially, after + * starting to run the guest, used_length and postcopy_length can differ. + * Used to register/unregister uffd handlers and as the size of the received + * bitmap. Receiving any page beyond this length will bail out, as it + * could not have been valid on the source. + */ + ram_addr_t postcopy_length; }; #endif #endif diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c index ab482adef1..2e9697bdd2 100644 --- a/migration/postcopy-ram.c +++ b/migration/postcopy-ram.c @@ -17,6 +17,7 @@ */ #include "qemu/osdep.h" +#include "qemu/rcu.h" #include "exec/target_page.h" #include "migration.h" #include "qemu-file.h" @@ -30,6 +31,7 @@ #include "qemu/error-report.h" #include "trace.h" #include "hw/boards.h" +#include "exec/ramblock.h" /* Arbitrary limit on size of each discard command, * keeps them around ~200 bytes @@ -452,6 +454,13 @@ static int init_range(RAMBlock *rb, void *opaque) ram_addr_t length = qemu_ram_get_used_length(rb); trace_postcopy_init_range(block_name, host_addr, offset, length); + /* + * Save the used_length before running the guest. In case we have to + * resize RAM blocks when syncing RAM block sizes from the source during + * precopy, we'll update it manually via the ram block notifier. + */ + rb->postcopy_length = length; + /* * We need the whole of RAM to be truly empty for postcopy, so things * like ROMs and any data tables built during init must be zero'd @@ -474,7 +483,7 @@ static int cleanup_range(RAMBlock *rb, void *opaque) const char *block_name = qemu_ram_get_idstr(rb); void *host_addr = qemu_ram_get_host_addr(rb); ram_addr_t offset = qemu_ram_get_offset(rb); - ram_addr_t length = qemu_ram_get_used_length(rb); + ram_addr_t length = rb->postcopy_length; MigrationIncomingState *mis = opaque; struct uffdio_range range_struct; trace_postcopy_cleanup_range(block_name, host_addr, offset, length); @@ -580,7 +589,7 @@ static int nhp_range(RAMBlock *rb, void *opaque) const char *block_name = qemu_ram_get_idstr(rb); void *host_addr = qemu_ram_get_host_addr(rb); ram_addr_t offset = qemu_ram_get_offset(rb); - ram_addr_t length = qemu_ram_get_used_length(rb); + ram_addr_t length = rb->postcopy_length; trace_postcopy_nhp_range(block_name, host_addr, offset, length); /* @@ -624,7 +633,7 @@ static int ram_block_enable_notify(RAMBlock *rb, void *opaque) struct uffdio_register reg_struct; reg_struct.range.start = (uintptr_t)qemu_ram_get_host_addr(rb); - reg_struct.range.len = qemu_ram_get_used_length(rb); + reg_struct.range.len = rb->postcopy_length; reg_struct.mode = UFFDIO_REGISTER_MODE_MISSING; /* Now tell our userfault_fd that it's responsible for this area */ diff --git a/migration/ram.c b/migration/ram.c index 26ed42b87d..6d09ca78bc 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -240,7 +240,7 @@ int64_t ramblock_recv_bitmap_send(QEMUFile *file, return -1; } - nbits = block->used_length >> TARGET_PAGE_BITS; + nbits = block->postcopy_length >> TARGET_PAGE_BITS; /* * Make sure the tmp bitmap buffer is big enough, e.g., on 32bit @@ -3530,7 +3530,13 @@ static int ram_load_postcopy(QEMUFile *f) break; } - if (!offset_in_ramblock(block, addr)) { + /* + * Relying on used_length is racy and can result in false positives. + * We might place pages beyond used_length in case RAM was shrunk + * while in postcopy, which is fine - trying to place via + * UFFDIO_COPY/UFFDIO_ZEROPAGE will never segfault. + */ + if (!block->host || addr >= block->postcopy_length) { error_report("Illegal RAM offset " RAM_ADDR_FMT, addr); ret = -EINVAL; break; @@ -4143,6 +4149,7 @@ static void ram_mig_ram_block_resized(RAMBlockNotifier *n, void *host, rb->idstr); } } + rb->postcopy_length = new_size; break; case POSTCOPY_INCOMING_NONE: case POSTCOPY_INCOMING_RUNNING: -- cgit v1.2.3-55-g7522