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AJvYcCWENokx/+81SH1NmMp+Qw2s2SPjiGGhoLyjEUS1RuqYPDsJxty9TBEDe6A8qRKE6Tz3UKibz0lr3jw080Y=@vger.kernel.org X-Gm-Message-State: AOJu0YxkmFoOuaCTRBZEjskArFrxb5rR2hnBMIEWd5rWS4qQdie/wSUw DEWjO8nx86Ny1001lSto+Ngyr+IonThhz8P07/tnO3Pj5SamBrspAwyiWpu2nqrjpFRw44Zn0xU nbg== X-Google-Smtp-Source: AGHT+IGYUMRc1uUxr912DKcgHH4gUUnvf0wLEKnF8dkY5ruUFOJLgoqFTBS1LD3evC3JUrfTD0ZWGbhz678= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a17:902:cecd:b0:1fd:6529:7443 with SMTP id d9443c01a7336-1ff0486a65amr545105ad.11.1722038027663; Fri, 26 Jul 2024 16:53:47 -0700 (PDT) Reply-To: Sean Christopherson Date: Fri, 26 Jul 2024 16:51:43 -0700 In-Reply-To: <20240726235234.228822-1-seanjc@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20240726235234.228822-1-seanjc@google.com> X-Mailer: git-send-email 2.46.0.rc1.232.g9752f9e123-goog Message-ID: <20240726235234.228822-35-seanjc@google.com> Subject: [PATCH v12 34/84] KVM: Add a helper to lookup a pfn without grabbing a reference From: Sean Christopherson To: Paolo Bonzini , 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 , Sean Christopherson 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 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Add a kvm_follow_pfn() wrapper, kvm_lookup_pfn(), to allow looking up a gfn=3D>pfn mapping without the caller getting a reference to any underlying page. The API will be used in flows that want to know if a gfn points at a valid pfn, but don't actually need to do anything with the pfn. Signed-off-by: Sean Christopherson --- include/linux/kvm_host.h | 2 ++ virt/kvm/kvm_main.c | 16 ++++++++++++++++ 2 files changed, 18 insertions(+) diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 82ca0971c156..5a572cef4adc 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -1212,6 +1212,8 @@ static inline void kvm_release_page_unused(struct pag= e *page) void kvm_release_page_clean(struct page *page); void kvm_release_page_dirty(struct page *page); =20 +kvm_pfn_t kvm_lookup_pfn(struct kvm *kvm, gfn_t gfn); + kvm_pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn); kvm_pfn_t gfn_to_pfn_prot(struct kvm *kvm, gfn_t gfn, bool write_fault, bool *writable); diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 0b3c0bddaa07..ad84dab8c5dc 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -3118,6 +3118,22 @@ kvm_pfn_t kvm_vcpu_gfn_to_pfn(struct kvm_vcpu *vcpu,= gfn_t gfn) } EXPORT_SYMBOL_GPL(kvm_vcpu_gfn_to_pfn); =20 +kvm_pfn_t kvm_lookup_pfn(struct kvm *kvm, gfn_t gfn) +{ + struct page *refcounted_page =3D NULL; + struct kvm_follow_pfn kfp =3D { + .slot =3D gfn_to_memslot(kvm, gfn), + .gfn =3D gfn, + .flags =3D FOLL_WRITE, + .refcounted_page =3D &refcounted_page, + }; + kvm_pfn_t pfn; + + pfn =3D kvm_follow_pfn(&kfp); + kvm_release_page_unused(refcounted_page); + return pfn; +} + int kvm_prefetch_pages(struct kvm_memory_slot *slot, gfn_t gfn, struct page **pages, int nr_pages) { --=20 2.46.0.rc1.232.g9752f9e123-goog