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Tue, 30 Jul 2024 02:05:38 -0700 (PDT) X-Google-Smtp-Source: AGHT+IGyHe4aJyS1Uxr4GJW4wjt2WBKjxS53+1D2JV4zXUtkqi7IDeNByS7dwef5YTgCXCGFtY96FA== X-Received: by 2002:a17:907:9803:b0:a6f:4f2c:1936 with SMTP id a640c23a62f3a-a7d4011446bmr605763366b.44.1722330337702; Tue, 30 Jul 2024 02:05:37 -0700 (PDT) Received: from [192.168.10.47] ([151.95.101.29]) by smtp.googlemail.com with ESMTPSA id a640c23a62f3a-a7acab23157sm617304466b.33.2024.07.30.02.05.36 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 30 Jul 2024 02:05:37 -0700 (PDT) Message-ID: <2da6b57e-d5c2-4016-b89b-d51700eeb845@redhat.com> Date: Tue, 30 Jul 2024 11:05:35 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v12 45/84] KVM: guest_memfd: Provide "struct page" as output from kvm_gmem_get_pfn() To: Sean Christopherson , Marc Zyngier , Oliver Upton , Tianrui Zhao , Bibo Mao , Huacai Chen , Michael Ellerman , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Christian Borntraeger , Janosch Frank , Claudio Imbrenda Cc: kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, David Matlack , David Stevens References: <20240726235234.228822-1-seanjc@google.com> <20240726235234.228822-46-seanjc@google.com> From: Paolo Bonzini Autocrypt: addr=pbonzini@redhat.com; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240730_020545_440114_DA1762E2 X-CRM114-Status: GOOD ( 17.72 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 7/27/24 01:51, Sean Christopherson wrote: > Provide the "struct page" associated with a guest_memfd pfn as an output > from __kvm_gmem_get_pfn() so that KVM guest page fault handlers can ^^^^^^^^^^^^^^^^^^^^ Just "kvm_gmem_get_pfn()". > directly put the page instead of having to rely on > kvm_pfn_to_refcounted_page(). This will conflict with my series, where I'm introducing folio_file_pfn() and using it here: > - page = folio_file_page(folio, index); > + *page = folio_file_page(folio, index); > > - *pfn = page_to_pfn(page); > + *pfn = page_to_pfn(*page); > if (max_order) > *max_order = 0; That said, I think it's better to turn kvm_gmem_get_pfn() into kvm_gmem_get_page() here, and pull the page_to_pfn() or page_to_phys() to the caller as applicable. This highlights that the caller always gets a refcounted page with guest_memfd. diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 901be9e420a4..bcc4a4c594ef 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -4348,13 +4348,14 @@ static int kvm_faultin_pfn_private(struct kvm_vcpu *vcpu, return -EFAULT; } - r = kvm_gmem_get_pfn(vcpu->kvm, fault->slot, fault->gfn, &fault->pfn, + r = kvm_gmem_get_page(vcpu->kvm, fault->slot, fault->gfn, &fault->refcounted_page, &max_order); if (r) { kvm_mmu_prepare_memory_fault_exit(vcpu, fault); return r; } + fault->pfn = page_to_pfn(page); fault->map_writable = !(fault->slot->flags & KVM_MEM_READONLY); fault->max_level = kvm_max_private_mapping_level(vcpu->kvm, fault->pfn, fault->max_level, max_order); diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index a16c873b3232..db4181d11f2e 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -3847,7 +3847,7 @@ static int __sev_snp_update_protected_guest_state(struct kvm_vcpu *vcpu) if (VALID_PAGE(svm->sev_es.snp_vmsa_gpa)) { gfn_t gfn = gpa_to_gfn(svm->sev_es.snp_vmsa_gpa); struct kvm_memory_slot *slot; - kvm_pfn_t pfn; + struct page *page; slot = gfn_to_memslot(vcpu->kvm, gfn); if (!slot) @@ -3857,7 +3857,7 @@ static int __sev_snp_update_protected_guest_state(struct kvm_vcpu *vcpu) * The new VMSA will be private memory guest memory, so * retrieve the PFN from the gmem backend. */ - if (kvm_gmem_get_pfn(vcpu->kvm, slot, gfn, &pfn, NULL)) + if (kvm_gmem_get_page(vcpu->kvm, slot, gfn, &page, NULL)) return -EINVAL; /* @@ -3873,7 +3873,7 @@ static int __sev_snp_update_protected_guest_state(struct kvm_vcpu *vcpu) svm->sev_es.snp_has_guest_vmsa = true; /* Use the new VMSA */ - svm->vmcb->control.vmsa_pa = pfn_to_hpa(pfn); + svm->vmcb->control.vmsa_pa = page_to_phys(page); /* Mark the vCPU as runnable */ vcpu->arch.pv.pv_unhalted = false; @@ -3886,7 +3886,7 @@ static int __sev_snp_update_protected_guest_state(struct kvm_vcpu *vcpu) * changes then care should be taken to ensure * svm->sev_es.vmsa is pinned through some other means. */ - kvm_release_pfn_clean(pfn); + kvm_release_page_clean(page); } /* @@ -4687,6 +4687,7 @@ void sev_handle_rmp_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u64 error_code) struct kvm *kvm = vcpu->kvm; int order, rmp_level, ret; bool assigned; + struct page *page; kvm_pfn_t pfn; gfn_t gfn; @@ -4712,13 +4713,14 @@ void sev_handle_rmp_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u64 error_code) return; } - ret = kvm_gmem_get_pfn(kvm, slot, gfn, &pfn, &order); + ret = kvm_gmem_get_page(kvm, slot, gfn, &page, &order); if (ret) { pr_warn_ratelimited("SEV: Unexpected RMP fault, no backing page for private GPA 0x%llx\n", gpa); return; } + pfn = page_to_pfn(page); ret = snp_lookup_rmpentry(pfn, &assigned, &rmp_level); if (ret || !assigned) { pr_warn_ratelimited("SEV: Unexpected RMP fault, no assigned RMP entry found for GPA 0x%llx PFN 0x%llx error %d\n", @@ -4770,7 +4772,7 @@ void sev_handle_rmp_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u64 error_code) out: trace_kvm_rmp_fault(vcpu, gpa, pfn, error_code, rmp_level, ret); out_no_trace: - put_page(pfn_to_page(pfn)); + kvm_release_page_unused(page); } static bool is_pfn_range_shared(kvm_pfn_t start, kvm_pfn_t end) And the change in virt/kvm/guest_memfd.c then is just as trivial, apart from all the renaming: - *pfn = folio_file_pfn(folio, index); + *page = folio_file_page(folio, index); Paolo