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AJvYcCWE4FMK2/XaP/nOnPGeqeABheNRS2nMIsRwk8Eg17gyFVIHamQjlJ//sGIYdflAORlCCntO8Kn1lw==@kvack.org X-Gm-Message-State: AOJu0YzPVLmK1uT7HrCX9SiSICt9+IWv4bR/syDEDWPN58LFeSG4AobS R5T56CChpoCIpP0w0AMFRbV0jzbTVPASXaXZxhfcE2zcIU/6HwFaN31iSpa9j+55LHmF6ivkH2N Xhg== X-Google-Smtp-Source: AGHT+IGbecgOoimuhgq7GBsyMfiouaKkyce/B8FWdopk44Xy71H+G8NRPUx2Bg44d+1+Ni1BCYWnqV0plA== X-Received: from wmbbi11.prod.google.com ([2002:a05:600c:3d8b:b0:44a:ebc5:9921]) (user=tabba job=prod-delivery.src-stubby-dispatcher) by 2002:a05:600c:37cf:b0:450:d01f:de6f with SMTP id 5b1f17b1804b1-454d53087f8mr22468195e9.15.1752058816177; Wed, 09 Jul 2025 04:00:16 -0700 (PDT) Date: Wed, 9 Jul 2025 11:59:39 +0100 In-Reply-To: <20250709105946.4009897-1-tabba@google.com> Mime-Version: 1.0 References: <20250709105946.4009897-1-tabba@google.com> X-Mailer: git-send-email 2.50.0.727.gbf7dc18ff4-goog Message-ID: <20250709105946.4009897-14-tabba@google.com> Subject: [PATCH v13 13/20] KVM: x86/mmu: Handle guest page faults for guest_memfd with shared memory From: Fuad Tabba To: kvm@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-mm@kvack.org, kvmarm@lists.linux.dev Cc: pbonzini@redhat.com, chenhuacai@kernel.org, mpe@ellerman.id.au, anup@brainfault.org, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, seanjc@google.com, viro@zeniv.linux.org.uk, brauner@kernel.org, willy@infradead.org, akpm@linux-foundation.org, xiaoyao.li@intel.com, yilun.xu@intel.com, chao.p.peng@linux.intel.com, jarkko@kernel.org, amoorthy@google.com, dmatlack@google.com, isaku.yamahata@intel.com, mic@digikod.net, vbabka@suse.cz, vannapurve@google.com, ackerleytng@google.com, mail@maciej.szmigiero.name, david@redhat.com, michael.roth@amd.com, wei.w.wang@intel.com, liam.merwick@oracle.com, isaku.yamahata@gmail.com, kirill.shutemov@linux.intel.com, suzuki.poulose@arm.com, steven.price@arm.com, quic_eberman@quicinc.com, quic_mnalajal@quicinc.com, quic_tsoni@quicinc.com, quic_svaddagi@quicinc.com, quic_cvanscha@quicinc.com, quic_pderrin@quicinc.com, quic_pheragu@quicinc.com, catalin.marinas@arm.com, james.morse@arm.com, yuzenghui@huawei.com, oliver.upton@linux.dev, maz@kernel.org, will@kernel.org, qperret@google.com, keirf@google.com, roypat@amazon.co.uk, shuah@kernel.org, hch@infradead.org, jgg@nvidia.com, rientjes@google.com, jhubbard@nvidia.com, fvdl@google.com, hughd@google.com, jthoughton@google.com, peterx@redhat.com, pankaj.gupta@amd.com, ira.weiny@intel.com, tabba@google.com Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: A79EFC000B X-Stat-Signature: 9iyscwe5disme55udk8sjbocnmquq36i X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1752058817-532310 X-HE-Meta: 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 EdUXK9yH 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: Ackerley Tng Update the KVM MMU fault handler to service guest page faults for memory slots backed by guest_memfd with mmap support. For such slots, the MMU must always fault in pages directly from guest_memfd, bypassing the host's userspace_addr. This ensures that guest_memfd-backed memory is always handled through the guest_memfd specific faulting path, regardless of whether it's for private or non-private (shared) use cases. Additionally, rename kvm_mmu_faultin_pfn_private() to kvm_mmu_faultin_pfn_gmem(), as this function is now used to fault in pages from guest_memfd for both private and non-private memory, accommodating the new use cases. Co-developed-by: David Hildenbrand Signed-off-by: David Hildenbrand Signed-off-by: Ackerley Tng Co-developed-by: Fuad Tabba Signed-off-by: Fuad Tabba --- arch/x86/kvm/mmu/mmu.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 6d997063f76f..cc4cdfea343b 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -4511,8 +4511,8 @@ static void kvm_mmu_finish_page_fault(struct kvm_vcpu *vcpu, r == RET_PF_RETRY, fault->map_writable); } -static int kvm_mmu_faultin_pfn_private(struct kvm_vcpu *vcpu, - struct kvm_page_fault *fault) +static int kvm_mmu_faultin_pfn_gmem(struct kvm_vcpu *vcpu, + struct kvm_page_fault *fault) { int max_order, r; @@ -4537,13 +4537,18 @@ static int kvm_mmu_faultin_pfn_private(struct kvm_vcpu *vcpu, return RET_PF_CONTINUE; } +static bool fault_from_gmem(struct kvm_page_fault *fault) +{ + return fault->is_private || kvm_memslot_is_gmem_only(fault->slot); +} + static int __kvm_mmu_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) { unsigned int foll = fault->write ? FOLL_WRITE : 0; - if (fault->is_private) - return kvm_mmu_faultin_pfn_private(vcpu, fault); + if (fault_from_gmem(fault)) + return kvm_mmu_faultin_pfn_gmem(vcpu, fault); foll |= FOLL_NOWAIT; fault->pfn = __kvm_faultin_pfn(fault->slot, fault->gfn, foll, -- 2.50.0.727.gbf7dc18ff4-goog