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Tue, 30 Jul 2024 01:58:35 -0700 (PDT) X-Google-Smtp-Source: AGHT+IHAOIIltVQdWTS+wB0eMPC1Ma/f+US5vc2+G0XsatRnSCbICJZcTeRE4zXEmrhssvwMjnoa3g== X-Received: by 2002:a19:6a0e:0:b0:52e:fa14:cc96 with SMTP id 2adb3069b0e04-5309b27e54dmr7004170e87.34.1722329914765; Tue, 30 Jul 2024 01:58:34 -0700 (PDT) Received: from [192.168.10.47] ([151.95.101.29]) by smtp.googlemail.com with ESMTPSA id a640c23a62f3a-a7acab23125sm616347566b.1.2024.07.30.01.58.33 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 30 Jul 2024 01:58:34 -0700 (PDT) Message-ID: <96df1dd5-cc31-4e84-84fd-ea75b4800be8@redhat.com> Date: Tue, 30 Jul 2024 10:58:32 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v12 48/84] KVM: Move x86's API to release a faultin page to common KVM 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> <20240726235234.228822-49-seanjc@google.com> From: Paolo Bonzini Autocrypt: addr=pbonzini@redhat.com; keydata= xsEhBFRCcBIBDqDGsz4K0zZun3jh+U6Z9wNGLKQ0kSFyjN38gMqU1SfP+TUNQepFHb/Gc0E2 CxXPkIBTvYY+ZPkoTh5xF9oS1jqI8iRLzouzF8yXs3QjQIZ2SfuCxSVwlV65jotcjD2FTN04 hVopm9llFijNZpVIOGUTqzM4U55sdsCcZUluWM6x4HSOdw5F5Utxfp1wOjD/v92Lrax0hjiX DResHSt48q+8FrZzY+AUbkUS+Jm34qjswdrgsC5uxeVcLkBgWLmov2kMaMROT0YmFY6A3m1S P/kXmHDXxhe23gKb3dgwxUTpENDBGcfEzrzilWueOeUWiOcWuFOed/C3SyijBx3Av/lbCsHU Vx6pMycNTdzU1BuAroB+Y3mNEuW56Yd44jlInzG2UOwt9XjjdKkJZ1g0P9dwptwLEgTEd3Fo UdhAQyRXGYO8oROiuh+RZ1lXp6AQ4ZjoyH8WLfTLf5g1EKCTc4C1sy1vQSdzIRu3rBIjAvnC tGZADei1IExLqB3uzXKzZ1BZ+Z8hnt2og9hb7H0y8diYfEk2w3R7wEr+Ehk5NQsT2MPI2QBd wEv1/Aj1DgUHZAHzG1QN9S8wNWQ6K9DqHZTBnI1hUlkp22zCSHK/6FwUCuYp1zcAEQEAAc0j UGFvbG8gQm9uemluaSA8cGJvbnppbmlAcmVkaGF0LmNvbT7CwU0EEwECACMFAlRCcBICGwMH CwkIBwMCAQYVCAIJCgsEFgIDAQIeAQIXgAAKCRB+FRAMzTZpsbceDp9IIN6BIA0Ol7MoB15E 11kRz/ewzryFY54tQlMnd4xxfH8MTQ/mm9I482YoSwPMdcWFAKnUX6Yo30tbLiNB8hzaHeRj jx12K+ptqYbg+cevgOtbLAlL9kNgLLcsGqC2829jBCUTVeMSZDrzS97ole/YEez2qFpPnTV0 VrRWClWVfYh+JfzpXmgyhbkuwUxNFk421s4Ajp3d8nPPFUGgBG5HOxzkAm7xb1cjAuJ+oi/K CHfkuN+fLZl/u3E/fw7vvOESApLU5o0icVXeakfSz0LsygEnekDbxPnE5af/9FEkXJD5EoYG SEahaEtgNrR4qsyxyAGYgZlS70vkSSYJ+iT2rrwEiDlo31MzRo6Ba2FfHBSJ7lcYdPT7bbk9 AO3hlNMhNdUhoQv7M5HsnqZ6unvSHOKmReNaS9egAGdRN0/GPDWr9wroyJ65ZNQsHl9nXBqE AukZNr5oJO5vxrYiAuuTSd6UI/xFkjtkzltG3mw5ao2bBpk/V/YuePrJsnPFHG7NhizrxttB nTuOSCMo45pfHQ+XYd5K1+Cv/NzZFNWscm5htJ0HznY+oOsZvHTyGz3v91pn51dkRYN0otqr bQ4tlFFuVjArBZcapSIe6NV8C4cEiSTOwE0EVEJx7gEIAMeHcVzuv2bp9HlWDp6+RkZe+vtl KwAHplb/WH59j2wyG8V6i33+6MlSSJMOFnYUCCL77bucx9uImI5nX24PIlqT+zasVEEVGSRF m8dgkcJDB7Tps0IkNrUi4yof3B3shR+vMY3i3Ip0e41zKx0CvlAhMOo6otaHmcxr35sWq1Jk tLkbn3wG+fPQCVudJJECvVQ//UAthSSEklA50QtD2sBkmQ14ZryEyTHQ+E42K3j2IUmOLriF dNr9NvE1QGmGyIcbw2NIVEBOK/GWxkS5+dmxM2iD4Jdaf2nSn3jlHjEXoPwpMs0KZsgdU0pP JQzMUMwmB1wM8JxovFlPYrhNT9MAEQEAAcLBMwQYAQIACQUCVEJx7gIbDAAKCRB+FRAMzTZp sadRDqCctLmYICZu4GSnie4lKXl+HqlLanpVMOoFNnWs9oRP47MbE2wv8OaYh5pNR9VVgyhD OG0AU7oidG36OeUlrFDTfnPYYSF/mPCxHttosyt8O5kabxnIPv2URuAxDByz+iVbL+RjKaGM GDph56ZTswlx75nZVtIukqzLAQ5fa8OALSGum0cFi4ptZUOhDNz1onz61klD6z3MODi0sBZN Aj6guB2L/+2ZwElZEeRBERRd/uommlYuToAXfNRdUwrwl9gRMiA0WSyTb190zneRRDfpSK5d usXnM/O+kr3Dm+Ui+UioPf6wgbn3T0o6I5BhVhs4h4hWmIW7iNhPjX1iybXfmb1gAFfjtHfL xRUr64svXpyfJMScIQtBAm0ihWPltXkyITA92ngCmPdHa6M1hMh4RDX+Jf1fiWubzp1voAg0 JBrdmNZSQDz0iKmSrx8xkoXYfA3bgtFN8WJH2xgFL28XnqY4M6dLhJwV3z08tPSRqYFm4NMP dRsn0/7oymhneL8RthIvjDDQ5ktUjMe8LtHr70OZE/TT88qvEdhiIVUogHdo4qBrk41+gGQh b906Dudw5YhTJFU3nC6bbF2nrLlB4C/XSiH76ZvqzV0Z/cAMBo5NF/w= In-Reply-To: <20240726235234.228822-49-seanjc@google.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; 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_015841_157648_461C9784 X-CRM114-Status: GOOD ( 22.99 ) 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: > Move KVM x86's helper that "finishes" the faultin process to common KVM > so that the logic can be shared across all architectures. Note, not all > architectures implement a fast page fault path, but the gist of the > comment applies to all architectures. > > Signed-off-by: Sean Christopherson > --- > arch/x86/kvm/mmu/mmu.c | 24 ++---------------------- > include/linux/kvm_host.h | 26 ++++++++++++++++++++++++++ > 2 files changed, 28 insertions(+), 22 deletions(-) > > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c > index 95beb50748fc..2a0cfa225c8d 100644 > --- a/arch/x86/kvm/mmu/mmu.c > +++ b/arch/x86/kvm/mmu/mmu.c > @@ -4323,28 +4323,8 @@ static u8 kvm_max_private_mapping_level(struct kvm *kvm, kvm_pfn_t pfn, > static void kvm_mmu_finish_page_fault(struct kvm_vcpu *vcpu, > struct kvm_page_fault *fault, int r) > { > - lockdep_assert_once(lockdep_is_held(&vcpu->kvm->mmu_lock) || > - r == RET_PF_RETRY); > - > - if (!fault->refcounted_page) > - return; > - > - /* > - * If the page that KVM got from the *primary MMU* is writable, and KVM > - * installed or reused a SPTE, mark the page/folio dirty. Note, this > - * may mark a folio dirty even if KVM created a read-only SPTE, e.g. if > - * the GFN is write-protected. Folios can't be safely marked dirty > - * outside of mmu_lock as doing so could race with writeback on the > - * folio. As a result, KVM can't mark folios dirty in the fast page > - * fault handler, and so KVM must (somewhat) speculatively mark the > - * folio dirty if KVM could locklessly make the SPTE writable. > - */ > - if (r == RET_PF_RETRY) > - kvm_release_page_unused(fault->refcounted_page); > - else if (!fault->map_writable) > - kvm_release_page_clean(fault->refcounted_page); > - else > - kvm_release_page_dirty(fault->refcounted_page); > + kvm_release_faultin_page(vcpu->kvm, fault->refcounted_page, > + r == RET_PF_RETRY, fault->map_writable); Does it make sense to move RET_PF_* to common code, and avoid a bool argument here? Paolo > } > > static int kvm_mmu_faultin_pfn_private(struct kvm_vcpu *vcpu, > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > index 9d2a97eb30e4..91341cdc6562 100644 > --- a/include/linux/kvm_host.h > +++ b/include/linux/kvm_host.h > @@ -1216,6 +1216,32 @@ static inline void kvm_release_page_unused(struct page *page) > void kvm_release_page_clean(struct page *page); > void kvm_release_page_dirty(struct page *page); > > +static inline void kvm_release_faultin_page(struct kvm *kvm, struct page *page, > + bool unused, bool dirty) > +{ > + lockdep_assert_once(lockdep_is_held(&kvm->mmu_lock) || unused); > + > + if (!page) > + return; > + > + /* > + * If the page that KVM got from the *primary MMU* is writable, and KVM > + * installed or reused a SPTE, mark the page/folio dirty. Note, this > + * may mark a folio dirty even if KVM created a read-only SPTE, e.g. if > + * the GFN is write-protected. Folios can't be safely marked dirty > + * outside of mmu_lock as doing so could race with writeback on the > + * folio. As a result, KVM can't mark folios dirty in the fast page > + * fault handler, and so KVM must (somewhat) speculatively mark the > + * folio dirty if KVM could locklessly make the SPTE writable. > + */ > + if (unused) > + kvm_release_page_unused(page); > + else if (dirty) > + kvm_release_page_dirty(page); > + else > + kvm_release_page_clean(page); > +} > + > kvm_pfn_t kvm_lookup_pfn(struct kvm *kvm, gfn_t gfn); > kvm_pfn_t __kvm_faultin_pfn(const struct kvm_memory_slot *slot, gfn_t gfn, > unsigned int foll, bool *writable,