| Message ID | 20201217154118.16497-1-jiangshanlai@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | [V3] kvm: check tlbs_dirty directly | expand |
On 17/12/20 16:41, Lai Jiangshan wrote: > From: Lai Jiangshan <laijs@linux.alibaba.com> > > 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> > --- > Changed from V1: > Update the patch and the changelog as Sean Christopherson suggested. > > Changed from v2: > don't change the type of need_tlb_flush > > virt/kvm/kvm_main.c | 3 +-- > 1 file changed, 1 insertion(+), 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); > Queued, thanks. Paolo
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);