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AJvYcCU19K6Gkmr/UFZN5fyH6u4psjXoUEYGrirwmCgOHOjHNKtoOnVzrIGfCA981bq3JbSfaAHTTfPYWQ==@kvack.org X-Gm-Message-State: AOJu0YyrJGOlJT79IpHfD2/s+Uu7fjA0arHuAw0w7RcUTTc0nEZ+52ek NjGBbZcbCeG9TmrDgzX3ZXGbdWME3JtJ5S7cx1zoroQm2l7GbHUOtW6p8H2YFXquFY6DDTXS1J5 Sog== X-Google-Smtp-Source: AGHT+IFT79H0JMSPNQLJqFCm8BSQjlOEJfCNJpa0mFxk/CyYzTNiLJDi9MX2K2oWjDCLOvzRxItf7JYjLQ== X-Received: from wmtk7.prod.google.com ([2002:a05:600c:c4a7:b0:455:9043:a274]) (user=tabba job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6000:400f:b0:3a5:2653:7322 with SMTP id ffacd0b85a97d-3b5f351d846mr12559005f8f.3.1752572059375; Tue, 15 Jul 2025 02:34:19 -0700 (PDT) Date: Tue, 15 Jul 2025 10:33:42 +0100 In-Reply-To: <20250715093350.2584932-1-tabba@google.com> Mime-Version: 1.0 References: <20250715093350.2584932-1-tabba@google.com> X-Mailer: git-send-email 2.50.0.727.gbf7dc18ff4-goog Message-ID: <20250715093350.2584932-14-tabba@google.com> Subject: [PATCH v14 13/21] 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: DF84B1C0007 X-Stat-Signature: u7bghxernqaqgy3mjxx31jrdf1cc89zk X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1752572060-911097 X-HE-Meta: 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 v2UfqTlm 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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 94be15cde6da..ad5f337b496c 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; @@ -4536,13 +4536,18 @@ 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