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[35.230.65.123]) by smtp.gmail.com with ESMTPSA id i6-20020a626d06000000b0051c09cdd71fsm13518188pfc.72.2022.06.22.07.19.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 22 Jun 2022 07:19:47 -0700 (PDT) Date: Wed, 22 Jun 2022 14:19:43 +0000 From: Sean Christopherson To: Paolo Bonzini Cc: David Matlack , Marc Zyngier , Huacai Chen , Aleksandar Markovic , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Andrew Jones , Ben Gardon , Peter Xu , maciej.szmigiero@oracle.com, "moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64)" , "open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips)" , "open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips)" , "open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv)" , Peter Feiner , Lai Jiangshan Subject: Re: [PATCH v6 03/22] KVM: x86/mmu: Stop passing @direct to mmu_alloc_root() Message-ID: References: <20220516232138.1783324-1-dmatlack@google.com> <20220516232138.1783324-4-dmatlack@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org On Wed, Jun 22, 2022, Paolo Bonzini wrote: > On 6/16/22 20:47, Sean Christopherson wrote: > > > The argument @direct is vcpu->arch.mmu->root_role.direct, so just use > > > that. > > It's worth calling out that, unlike non-root page tables, it's impossible to have > > a direct root in an indirect MMU. I.e. provide a hint as to why there's a need to > > pass @direct in the first place. > > > > I suppose there's *no* need to pass direct? Also, there's the trivial (but > less interesting) justification that kvm_mmu_load does > > if (vcpu->arch.mmu->root_role.direct) > r = mmu_alloc_direct_roots(vcpu); > else > r = mmu_alloc_shadow_roots(vcpu); > > and those are the only callers of mmu_alloc_root. Duh, you're right, grabbing root_role.direct in mmu_alloc_root() is much better. 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[35.230.65.123]) by smtp.gmail.com with ESMTPSA id i6-20020a626d06000000b0051c09cdd71fsm13518188pfc.72.2022.06.22.07.19.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 22 Jun 2022 07:19:47 -0700 (PDT) Date: Wed, 22 Jun 2022 14:19:43 +0000 From: Sean Christopherson To: Paolo Bonzini Subject: Re: [PATCH v6 03/22] KVM: x86/mmu: Stop passing @direct to mmu_alloc_root() Message-ID: References: <20220516232138.1783324-1-dmatlack@google.com> <20220516232138.1783324-4-dmatlack@google.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: Cc: Albert Ou , "open list:KERNEL VIRTUAL MACHINE FOR MIPS \(KVM/mips\)" , Marc Zyngier , Huacai Chen , Lai Jiangshan , "open list:KERNEL VIRTUAL MACHINE FOR MIPS \(KVM/mips\)" , Ben Gardon , Aleksandar Markovic , Palmer Dabbelt , "open list:KERNEL VIRTUAL MACHINE FOR RISC-V \(KVM/riscv\)" , Paul Walmsley , David Matlack , maciej.szmigiero@oracle.com, "moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 \(KVM/arm64\)" , Peter Feiner X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu On Wed, Jun 22, 2022, Paolo Bonzini wrote: > On 6/16/22 20:47, Sean Christopherson wrote: > > > The argument @direct is vcpu->arch.mmu->root_role.direct, so just use > > > that. > > It's worth calling out that, unlike non-root page tables, it's impossible to have > > a direct root in an indirect MMU. I.e. provide a hint as to why there's a need to > > pass @direct in the first place. > > > > I suppose there's *no* need to pass direct? Also, there's the trivial (but > less interesting) justification that kvm_mmu_load does > > if (vcpu->arch.mmu->root_role.direct) > r = mmu_alloc_direct_roots(vcpu); > else > r = mmu_alloc_shadow_roots(vcpu); > > and those are the only callers of mmu_alloc_root. Duh, you're right, grabbing root_role.direct in mmu_alloc_root() is much better. _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm