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| author | Lai Jiangshan <laijs@linux.alibaba.com> | 2020-12-17 23:41:18 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-02-23 13:58:14 +0100 |
| commit | 4230401d22d6365338c6cf8003d7d32f06d4680b (patch) | |
| tree | d01367461a9e7c45950dfe706a1bd42008dfc524 | |
| parent | 795d776b71c42aca3c616920da02368f646c5ad5 (diff) | |
| download | linux-stable-4230401d22d6365338c6cf8003d7d32f06d4680b.tar.gz linux-stable-4230401d22d6365338c6cf8003d7d32f06d4680b.tar.bz2 linux-stable-4230401d22d6365338c6cf8003d7d32f06d4680b.zip | |
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>
[sudip: adjust context]
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -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 ba8e8840b94b..b0326734a980 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -346,9 +346,8 @@ static void kvm_mmu_notifier_invalidate_range_start(struct mmu_notifier *mn, */ kvm->mmu_notifier_count++; need_tlb_flush = kvm_unmap_hva_range(kvm, start, end); - 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); |