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[35.230.65.123]) by smtp.gmail.com with ESMTPSA id bj23-20020a056a00319700b0052584b69a50sm218842pfb.66.2022.06.24.15.53.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 24 Jun 2022 15:53:29 -0700 (PDT) Date: Fri, 24 Jun 2022 22:53:25 +0000 From: Sean Christopherson To: Hou Wenlong Cc: kvm@vger.kernel.org, Paolo Bonzini , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Lan Tianyu , linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/5] KVM: x86/mmu: Fix wrong gfn range of tlb flushing in kvm_set_pte_rmapp() Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Fri, Jun 24, 2022, Hou Wenlong wrote: > When the spte of hupe page is dropped in kvm_set_pte_rmapp(), > the whole gfn range covered by the spte should be flushed. > However, rmap_walk_init_level() doesn't align down the gfn > for new level like tdp iterator does, then the gfn used in > kvm_set_pte_rmapp() is not the base gfn of huge page. And > the size of gfn range is wrong too for huge page. Since > the base gfn of huge page is more meaningful during the > rmap walking, so align down the gfn for new level and use > the correct size of huge page for tlb flushing in > kvm_set_pte_rmapp(). It's also worth noting that kvm_set_pte_rmapp() is the other user of the rmap iterators that consumes @gfn, i.e. modifying iterator->gfn is safe-ish. > Fixes: c3134ce240eed ("KVM: Replace old tlb flush function with new one to flush a specified range.") > Signed-off-by: Hou Wenlong > --- > arch/x86/kvm/mmu/mmu.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c > index b8a1f5b46b9d..37bfc88ea212 100644 > --- a/arch/x86/kvm/mmu/mmu.c > +++ b/arch/x86/kvm/mmu/mmu.c > @@ -1427,7 +1427,7 @@ static bool kvm_set_pte_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head, > } > > if (need_flush && kvm_available_flush_tlb_with_range()) { > - kvm_flush_remote_tlbs_with_address(kvm, gfn, 1); > + kvm_flush_remote_tlbs_with_address(kvm, gfn, KVM_PAGES_PER_HPAGE(level)); > return false; > } > > @@ -1455,7 +1455,7 @@ static void > rmap_walk_init_level(struct slot_rmap_walk_iterator *iterator, int level) > { > iterator->level = level; > - iterator->gfn = iterator->start_gfn; > + iterator->gfn = iterator->start_gfn & -KVM_PAGES_PER_HPAGE(level); Hrm, arguably this be done on start_gfn in slot_rmap_walk_init(). Having iter->gfn be less than iter->start_gfn will be odd. > iterator->rmap = gfn_to_rmap(iterator->gfn, level, iterator->slot); > iterator->end_rmap = gfn_to_rmap(iterator->end_gfn, level, iterator->slot); > } > -- > 2.31.1 >