migrate_ignore_shared() is an optimization that avoids copying memory that is visible and can be mapped on the target. However, a memory-backend-ram or a memory-backend-memfd block with the RAM_SHARED flag set is not migrated when migrate_ignore_shared() is true. This is wrong, because the block has no named backing store, and its contents will be lost. To fix, ignore shared memory iff it is a named file. Define a new flag RAM_NAMED_FILE to distinguish this case.
Signed-off-by: Steve Sistare <steven.sist...@oracle.com> --- backends/hostmem-file.c | 1 + include/exec/cpu-common.h | 1 + include/exec/memory.h | 3 +++ migration/ram.c | 3 ++- softmmu/physmem.c | 7 ++++++- 5 files changed, 13 insertions(+), 2 deletions(-) diff --git a/backends/hostmem-file.c b/backends/hostmem-file.c index 2514128..486d77d 100644 --- a/backends/hostmem-file.c +++ b/backends/hostmem-file.c @@ -56,6 +56,7 @@ file_backend_memory_alloc(HostMemoryBackend *backend, Error **errp) ram_flags = backend->share ? RAM_SHARED : 0; ram_flags |= backend->reserve ? 0 : RAM_NORESERVE; ram_flags |= fb->is_pmem ? RAM_PMEM : 0; + ram_flags |= RAM_NAMED_FILE; memory_region_init_ram_from_file(&backend->mr, OBJECT(backend), name, backend->size, fb->align, ram_flags, fb->mem_path, fb->readonly, errp); diff --git a/include/exec/cpu-common.h b/include/exec/cpu-common.h index 6feaa40..8173e3b 100644 --- a/include/exec/cpu-common.h +++ b/include/exec/cpu-common.h @@ -92,6 +92,7 @@ void qemu_ram_set_uf_zeroable(RAMBlock *rb); bool qemu_ram_is_migratable(RAMBlock *rb); void qemu_ram_set_migratable(RAMBlock *rb); void qemu_ram_unset_migratable(RAMBlock *rb); +bool qemu_ram_is_named_file(RAMBlock *rb); int qemu_ram_get_fd(RAMBlock *rb); size_t qemu_ram_pagesize(RAMBlock *block); diff --git a/include/exec/memory.h b/include/exec/memory.h index 2e602a2..3224e09 100644 --- a/include/exec/memory.h +++ b/include/exec/memory.h @@ -232,6 +232,9 @@ typedef struct IOMMUTLBEvent { /* RAM that isn't accessible through normal means. */ #define RAM_PROTECTED (1 << 8) +/* RAM is an mmap-ed named file */ +#define RAM_NAMED_FILE (1 << 9) + static inline void iommu_notifier_init(IOMMUNotifier *n, IOMMUNotify fn, IOMMUNotifierFlag flags, hwaddr start, hwaddr end, diff --git a/migration/ram.c b/migration/ram.c index 334309f..03f8131 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -190,7 +190,8 @@ static bool postcopy_preempt_active(void) bool ramblock_is_ignored(RAMBlock *block) { return !qemu_ram_is_migratable(block) || - (migrate_ignore_shared() && qemu_ram_is_shared(block)); + (migrate_ignore_shared() && qemu_ram_is_shared(block) && + qemu_ram_is_named_file(block)); } #undef RAMBLOCK_FOREACH diff --git a/softmmu/physmem.c b/softmmu/physmem.c index cb998cd..767a5f0 100644 --- a/softmmu/physmem.c +++ b/softmmu/physmem.c @@ -1749,6 +1749,11 @@ void qemu_ram_unset_migratable(RAMBlock *rb) rb->flags &= ~RAM_MIGRATABLE; } +bool qemu_ram_is_named_file(RAMBlock *rb) +{ + return rb->flags & RAM_NAMED_FILE; +} + int qemu_ram_get_fd(RAMBlock *rb) { return rb->fd; @@ -2059,7 +2064,7 @@ RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t size, MemoryRegion *mr, /* Just support these ram flags by now. */ assert((ram_flags & ~(RAM_SHARED | RAM_PMEM | RAM_NORESERVE | - RAM_PROTECTED)) == 0); + RAM_PROTECTED | RAM_NAMED_FILE)) == 0); if (xen_enabled()) { error_setg(errp, "-mem-path not supported with Xen"); -- 1.8.3.1