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authorLai Jiangshan <laijs@linux.alibaba.com>2020-12-17 18:41:18 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2021-02-23 16:00:34 +0300
commit3017f5e12bbfe19add7dc921caddc2a1c0066814 (patch)
treeb22a362d3bc37d45fcf2ec1a7de4f66b47b72b99 /virt/kvm
parent2afb9a5a42ab910589d3a3da96d365cb7085ff8b (diff)
downloadlinux-3017f5e12bbfe19add7dc921caddc2a1c0066814.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> [sudip: adjust context] Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'virt/kvm')
-rw-r--r--virt/kvm/kvm_main.c3
1 files changed, 1 insertions, 2 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index c1ca4d40157b..547ae59199db 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -382,9 +382,8 @@ 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);