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| author | Maciej S. Szmigiero <maciej.szmigiero@oracle.com> | 2020-12-05 01:48:08 +0100 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2020-12-11 19:18:43 -0500 |
| commit | 34c0f6f2695a2db81e09a3ab7bdb2853f45d4d3d (patch) | |
| tree | 8902487302d44024632c943bf6369fedd6cdefa1 /Documentation/virt | |
| parent | 83bbb8ffb4629ece5d6c0b093b9f66297a9e27e0 (diff) | |
KVM: mmu: Fix SPTE encoding of MMIO generation upper half
Commit cae7ed3c2cb0 ("KVM: x86: Refactor the MMIO SPTE generation handling")
cleaned up the computation of MMIO generation SPTE masks, however it
introduced a bug how the upper part was encoded:
SPTE bits 52-61 were supposed to contain bits 10-19 of the current
generation number, however a missing shift encoded bits 1-10 there instead
(mostly duplicating the lower part of the encoded generation number that
then consisted of bits 1-9).
In the meantime, the upper part was shrunk by one bit and moved by
subsequent commits to become an upper half of the encoded generation number
(bits 9-17 of bits 0-17 encoded in a SPTE).
In addition to the above, commit 56871d444bc4 ("KVM: x86: fix overlap between SPTE_MMIO_MASK and generation")
has changed the SPTE bit range assigned to encode the generation number and
the total number of bits encoded but did not update them in the comment
attached to their defines, nor in the KVM MMU doc.
Let's do it here, too, since it is too trivial thing to warrant a separate
commit.
Fixes: cae7ed3c2cb0 ("KVM: x86: Refactor the MMIO SPTE generation handling")
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Message-Id: <156700708db2a5296c5ed7a8b9ac71f1e9765c85.1607129096.git.maciej.szmigiero@oracle.com>
Cc: stable@vger.kernel.org
[Reorganize macros so that everything is computed from the bit ranges. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'Documentation/virt')
| -rw-r--r-- | Documentation/virt/kvm/mmu.rst | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/Documentation/virt/kvm/mmu.rst b/Documentation/virt/kvm/mmu.rst index 1c030dbac7c4..5bfe28b0728e 100644 --- a/Documentation/virt/kvm/mmu.rst +++ b/Documentation/virt/kvm/mmu.rst @@ -455,7 +455,7 @@ If the generation number of the spte does not equal the global generation number, it will ignore the cached MMIO information and handle the page fault through the slow path. -Since only 19 bits are used to store generation-number on mmio spte, all +Since only 18 bits are used to store generation-number on mmio spte, all pages are zapped when there is an overflow. Unfortunately, a single memory access might access kvm_memslots(kvm) multiple |