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| author | Paolo Bonzini <pbonzini@redhat.com> | 2019-04-17 15:28:44 +0200 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2019-04-30 21:32:19 +0200 |
| commit | 65c4189de8c1d995f6bc2cc96b22206405466b53 (patch) | |
| tree | 458839f13a2c760594db18f48c52cd9d1b267829 /Documentation | |
| parent | KVM: VMX: Skip delta_tsc shift-and-divide if the dividend is zero (diff) | |
| download | linux-65c4189de8c1d995f6bc2cc96b22206405466b53.tar.xz linux-65c4189de8c1d995f6bc2cc96b22206405466b53.zip | |
KVM: fix KVM_CLEAR_DIRTY_LOG for memory slots of unaligned size
If a memory slot's size is not a multiple of 64 pages (256K), then
the KVM_CLEAR_DIRTY_LOG API is unusable: clearing the final 64 pages
either requires the requested page range to go beyond memslot->npages,
or requires log->num_pages to be unaligned, and kvm_clear_dirty_log_protect
requires log->num_pages to be both in range and aligned.
To allow this case, allow log->num_pages not to be a multiple of 64 if
it ends exactly on the last page of the slot.
Reported-by: Peter Xu <peterx@redhat.com>
Fixes: 98938aa8edd6 ("KVM: validate userspace input in kvm_clear_dirty_log_protect()", 2019-01-02)
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/virtual/kvm/api.txt | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt index 26dc1280b49b..675cb0bea903 100644 --- a/Documentation/virtual/kvm/api.txt +++ b/Documentation/virtual/kvm/api.txt @@ -3812,8 +3812,9 @@ The ioctl clears the dirty status of pages in a memory slot, according to the bitmap that is passed in struct kvm_clear_dirty_log's dirty_bitmap field. Bit 0 of the bitmap corresponds to page "first_page" in the memory slot, and num_pages is the size in bits of the input bitmap. -Both first_page and num_pages must be a multiple of 64. For each bit -that is set in the input bitmap, the corresponding page is marked "clean" +first_page must be a multiple of 64; num_pages must also be a multiple of +64 unless first_page + num_pages is the size of the memory slot. For each +bit that is set in the input bitmap, the corresponding page is marked "clean" in KVM's dirty bitmap, and dirty tracking is re-enabled for that page (for example via write-protection, or by clearing the dirty bit in a page table entry). |