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physmem: Introduce ram_block_discard_guest_memfd_range()

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When memory page is converted from private to shared, the original
private memory is back'ed by guest_memfd. Introduce
ram_block_discard_guest_memfd_range() for discarding memory in
guest_memfd.

Based on a patch by Isaku Yamahata <isaku.yamahata@intel.com>.

Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Michael Roth <michael.roth@amd.com>
Message-ID: <20240320083945.991426-12-michael.roth@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Xiaoyao Li 2024-03-20 03:39:07 -05:00 committed by Paolo Bonzini
parent 852f0048f3
commit b2e9426c04
2 changed files with 25 additions and 0 deletions
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2
include/exec/cpu-common.h
View file

@ -159,6 +159,8 @@ typedef int (RAMBlockIterFunc)(RAMBlock *rb, void *opaque);
int qemu_ram_foreach_block(RAMBlockIterFunc func, void *opaque);
int ram_block_discard_range(RAMBlock *rb, uint64_t start, size_t length);
int ram_block_discard_guest_memfd_range(RAMBlock *rb, uint64_t start,
size_t length);
#endif

23
system/physmem.c
View file

@ -3721,6 +3721,29 @@ err:
return ret;
}
int ram_block_discard_guest_memfd_range(RAMBlock *rb, uint64_t start,
size_t length)
{
int ret = -1;
#ifdef CONFIG_FALLOCATE_PUNCH_HOLE
ret = fallocate(rb->guest_memfd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
start, length);
if (ret) {
ret = -errno;
error_report("%s: Failed to fallocate %s:%" PRIx64 " +%zx (%d)",
__func__, rb->idstr, start, length, ret);
}
#else
ret = -ENOSYS;
error_report("%s: fallocate not available %s:%" PRIx64 " +%zx (%d)",
__func__, rb->idstr, start, length, ret);
#endif
return ret;
}
bool ramblock_is_pmem(RAMBlock *rb)
{
return rb->flags & RAM_PMEM;