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[35.185.214.157]) by smtp.gmail.com with ESMTPSA id d2-20020a056a0024c200b004f6b6817549sm18217058pfv.173.2022.03.28.14.04.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 28 Mar 2022 14:04:23 -0700 (PDT) Date: Mon, 28 Mar 2022 21:04:19 +0000 From: Sean Christopherson To: Nikunj A Dadhania Cc: Paolo Bonzini , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Brijesh Singh , Tom Lendacky , Peter Gonda , Bharata B Rao , "Maciej S . Szmigiero" , Mingwei Zhang , David Hildenbrand , kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH RFC v1 2/9] KVM: x86/mmu: Move hugepage adjust to direct_page_fault Message-ID: References: <20220308043857.13652-1-nikunj@amd.com> <20220308043857.13652-3-nikunj@amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220308043857.13652-3-nikunj@amd.com> Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Tue, Mar 08, 2022, Nikunj A Dadhania wrote: > Both TDP MMU and legacy MMU do hugepage adjust in the mapping routine. > Adjust the pfn early in the common code. This will be used by the > following patches for pinning the pages. > > No functional change intended. There is a functional change here, as kvm_mmu_hugepage_adjust() is now called without mmu_lock being held. That really shouldn't be problematic, but sadly KVM very, very subtly relies on calling lookup_address_in_mm() while holding mmu_lock _and_ after checking mmu_notifier_retry_hva(). https://lore.kernel.org/all/CAL715WL7ejOBjzXy9vbS_M2LmvXcC-CxmNr+oQtCZW0kciozHA@mail.gmail.com > Signed-off-by: Nikunj A Dadhania > --- > arch/x86/kvm/mmu/mmu.c | 4 ++-- > arch/x86/kvm/mmu/tdp_mmu.c | 2 -- > 2 files changed, 2 insertions(+), 4 deletions(-) > > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c > index 8e24f73bf60b..db1feecd6fed 100644 > --- a/arch/x86/kvm/mmu/mmu.c > +++ b/arch/x86/kvm/mmu/mmu.c > @@ -2940,8 +2940,6 @@ static int __direct_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) > int ret; > gfn_t base_gfn = fault->gfn; > > - kvm_mmu_hugepage_adjust(vcpu, fault); > - > trace_kvm_mmu_spte_requested(fault); > for_each_shadow_entry(vcpu, fault->addr, it) { > /* > @@ -4035,6 +4033,8 @@ static int direct_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault > > r = RET_PF_RETRY; > > + kvm_mmu_hugepage_adjust(vcpu, fault); > + > if (is_tdp_mmu_fault) > read_lock(&vcpu->kvm->mmu_lock); > else > diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c > index bc9e3553fba2..e03bf59b2f81 100644 > --- a/arch/x86/kvm/mmu/tdp_mmu.c > +++ b/arch/x86/kvm/mmu/tdp_mmu.c > @@ -959,8 +959,6 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) > u64 new_spte; > int ret; > > - kvm_mmu_hugepage_adjust(vcpu, fault); > - > trace_kvm_mmu_spte_requested(fault); > > rcu_read_lock(); > -- > 2.32.0 >