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| author | Lai Jiangshan <laijs@linux.alibaba.com> | 2020-12-17 18:41:18 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-01-12 22:18:22 +0300 |
| commit | ffee6772c489d8d65d86979d4ccc4286624124b2 (patch) | |
| tree | 477fe476deefd1e45f4ba09ef7b5b274f778d943 /virt/kvm | |
| parent | f4064ef40c5c31134d6c360a1f1e9ec64e545ede (diff) | |
| download | linux-ffee6772c489d8d65d86979d4ccc4286624124b2.tar.xz | |
kvm: check tlbs_dirty directly
commit 88bf56d04bc3564542049ec4ec168a8b60d0b48c upstream.
In kvm_mmu_notifier_invalidate_range_start(), tlbs_dirty is used as:
need_tlb_flush |= kvm->tlbs_dirty;
with need_tlb_flush's type being int and tlbs_dirty's type being long.
It means that tlbs_dirty is always used as int and the higher 32 bits
is useless. We need to check tlbs_dirty in a correct way and this
change checks it directly without propagating it to need_tlb_flush.
Note: it's _extremely_ unlikely this neglecting of higher 32 bits can
cause problems in practice. It would require encountering tlbs_dirty
on a 4 billion count boundary, and KVM would need to be using shadow
paging or be running a nested guest.
Cc: stable@vger.kernel.org
Fixes: a4ee1ca4a36e ("KVM: MMU: delay flush all tlbs on sync_page path")
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Message-Id: <20201217154118.16497-1-jiangshanlai@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'virt/kvm')
| -rw-r--r-- | virt/kvm/kvm_main.c | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 2541a17ff1c4..3083fb53861d 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -482,9 +482,8 @@ static int kvm_mmu_notifier_invalidate_range_start(struct mmu_notifier *mn, kvm->mmu_notifier_count++; need_tlb_flush = kvm_unmap_hva_range(kvm, range->start, range->end, range->flags); - need_tlb_flush |= kvm->tlbs_dirty; /* we've to flush the tlb before the pages can be freed */ - if (need_tlb_flush) + if (need_tlb_flush || kvm->tlbs_dirty) kvm_flush_remote_tlbs(kvm); spin_unlock(&kvm->mmu_lock); |