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[2.98.59.96]) by smtp.gmail.com with ESMTPSA id u4sm5575434wrr.37.2021.02.17.14.00.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 17 Feb 2021 14:00:18 -0800 (PST) Date: Wed, 17 Feb 2021 22:00:16 +0000 From: Sudip Mukherjee To: gregkh@linuxfoundation.org Cc: laijs@linux.alibaba.com, pbonzini@redhat.com, stable@vger.kernel.org Subject: Re: FAILED: patch "[PATCH] kvm: check tlbs_dirty directly" failed to apply to 4.19-stable tree Message-ID: References: <1610354985142194@kroah.com> MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="VWHgY4RwVqrINEdd" Content-Disposition: inline In-Reply-To: <1610354985142194@kroah.com> Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org --VWHgY4RwVqrINEdd Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Hi Greg, On Mon, Jan 11, 2021 at 09:49:45AM +0100, gregkh@linuxfoundation.org wrote: > > The patch below does not apply to the 4.19-stable tree. > If someone wants it applied there, or to any other stable or longterm > tree, then please email the backport, including the original git commit > id to . Here is the backport. -- Regards Sudip --VWHgY4RwVqrINEdd Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="0001-kvm-check-tlbs_dirty-directly.patch" >From 17a6138c90d0816bb02f35a2600ffb67a00f64f7 Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Thu, 17 Dec 2020 23:41:18 +0800 Subject: [PATCH] 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 Message-Id: <20201217154118.16497-1-jiangshanlai@gmail.com> Signed-off-by: Paolo Bonzini [sudip: adjust context] Signed-off-by: Sudip Mukherjee --- 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 9312c7e750ed..1ecb27b3421a 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -412,9 +412,8 @@ static int kvm_mmu_notifier_invalidate_range_start(struct mmu_notifier *mn, */ kvm->mmu_notifier_count++; need_tlb_flush = kvm_unmap_hva_range(kvm, start, end, blockable); - 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); -- 2.30.0 --VWHgY4RwVqrINEdd--