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AJvYcCWSiPDPWDj5TIxDhzNwOYsY8Q4566hGMCw9x5sN8rUuTX6oICSPPKjmWHxFg2BnBIumGh3uNVYr0A==@kvack.org X-Gm-Message-State: AOJu0YwIsmmd0AWACagguAipPHV+9Mac4XAgNd/AfrIXCEiEGsEtDTXD 3lUF/RInQ//RWPEN27IDBJ3M9ghutBDRJXJxqnk3Dlo/tIUfMIOf9f3YxQBlzmWV1iYlHSHAMw= = X-Google-Smtp-Source: AGHT+IHYroJwqJU3DOFD6+1icl1H3re3zIaW22AGeBYXA+tL6iWDUUjy9KrUK9oxHqw8vDAQL5StNoyn7w== X-Received: from wmbbe15.prod.google.com ([2002:a05:600c:1e8f:b0:43d:1d5:26e6]) (user=tabba job=prod-delivery.src-stubby-dispatcher) by 2002:a05:600c:354a:b0:43c:f969:13c0 with SMTP id 5b1f17b1804b1-43d3ba284edmr36280275e9.29.1742314719101; Tue, 18 Mar 2025 09:18:39 -0700 (PDT) Date: Tue, 18 Mar 2025 16:18:21 +0000 In-Reply-To: <20250318161823.4005529-1-tabba@google.com> Mime-Version: 1.0 References: <20250318161823.4005529-1-tabba@google.com> X-Mailer: git-send-email 2.49.0.rc1.451.g8f38331e32-goog Message-ID: <20250318161823.4005529-8-tabba@google.com> Subject: [PATCH v7 7/9] KVM: arm64: Handle guest_memfd()-backed guest page faults From: Fuad Tabba To: kvm@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-mm@kvack.org 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, tabba@google.com X-Stat-Signature: hn8w3f3andbfusouq3qnboth4kk7odiw X-Rspamd-Queue-Id: 6ACA24001F X-Rspam-User: X-Rspamd-Server: rspam09 X-HE-Tag: 1742314720-781257 X-HE-Meta: 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 cwdypKWG ErtWoW3tZlHk9UgmbSDeZAHFTbWCVTvS9jZJvPLfaXXxcVhlcxJDysC/QlHknDrSNQlIZE6WNUeaHoB3MQKIADoN4aFI5ZBleaKZou66pibXNb4PHhddzKfz4TdDHQjZuQGs/jHj4CT0UIOK4R7QwiT+06QIGzS0TBNiyu+Ai76ESsX5WpcQKsNTZ9UWO7K06YcosmsDEX5gOGyeNETgAMedgwJwaZq7WXShh2bkowWWYM54KfVfo1YsBjolFs6zJJSp3+RI3NydDvBE+ocjOx0i9wCfqUoNpdmXuLDLE1lP4mZ1YYdevEg+2TYtgmu++g1siFZ+fNjipElTGHKOJnTHjQMJ8nvzvrjQtPNtIhieootE= 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: Add arm64 support for handling guest page faults on guest_memfd backed memslots. For now, the fault granule is restricted to PAGE_SIZE. Signed-off-by: Fuad Tabba --- arch/arm64/kvm/mmu.c | 65 +++++++++++++++++++++++++++------------- include/linux/kvm_host.h | 5 ++++ virt/kvm/kvm_main.c | 5 ---- 3 files changed, 50 insertions(+), 25 deletions(-) diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index 887ffa1f5b14..adb0681fc1c6 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c @@ -1454,6 +1454,30 @@ static bool kvm_vma_mte_allowed(struct vm_area_struct *vma) return vma->vm_flags & VM_MTE_ALLOWED; } +static kvm_pfn_t faultin_pfn(struct kvm *kvm, struct kvm_memory_slot *slot, + gfn_t gfn, bool write_fault, bool *writable, + struct page **page, bool is_private) +{ + kvm_pfn_t pfn; + int ret; + + if (!is_private) + return __kvm_faultin_pfn(slot, gfn, write_fault ? FOLL_WRITE : 0, writable, page); + + *writable = false; + + ret = kvm_gmem_get_pfn(kvm, slot, gfn, &pfn, page, NULL); + if (!ret) { + *writable = !memslot_is_readonly(slot); + return pfn; + } + + if (ret == -EHWPOISON) + return KVM_PFN_ERR_HWPOISON; + + return KVM_PFN_ERR_NOSLOT_MASK; +} + static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, struct kvm_s2_trans *nested, struct kvm_memory_slot *memslot, unsigned long hva, @@ -1461,19 +1485,20 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, { int ret = 0; bool write_fault, writable; - bool exec_fault, mte_allowed; + bool exec_fault, mte_allowed = false; bool device = false, vfio_allow_any_uc = false; unsigned long mmu_seq; phys_addr_t ipa = fault_ipa; struct kvm *kvm = vcpu->kvm; - struct vm_area_struct *vma; + struct vm_area_struct *vma = NULL; short vma_shift; void *memcache; - gfn_t gfn; + gfn_t gfn = ipa >> PAGE_SHIFT; kvm_pfn_t pfn; bool logging_active = memslot_is_logging(memslot); - bool force_pte = logging_active || is_protected_kvm_enabled(); - long vma_pagesize, fault_granule; + bool is_gmem = kvm_mem_is_private(kvm, gfn); + bool force_pte = logging_active || is_gmem || is_protected_kvm_enabled(); + long vma_pagesize, fault_granule = PAGE_SIZE; enum kvm_pgtable_prot prot = KVM_PGTABLE_PROT_R; struct kvm_pgtable *pgt; struct page *page; @@ -1510,16 +1535,22 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, return ret; } + mmap_read_lock(current->mm); + /* * Let's check if we will get back a huge page backed by hugetlbfs, or * get block mapping for device MMIO region. */ - mmap_read_lock(current->mm); - vma = vma_lookup(current->mm, hva); - if (unlikely(!vma)) { - kvm_err("Failed to find VMA for hva 0x%lx\n", hva); - mmap_read_unlock(current->mm); - return -EFAULT; + if (!is_gmem) { + vma = vma_lookup(current->mm, hva); + if (unlikely(!vma)) { + kvm_err("Failed to find VMA for hva 0x%lx\n", hva); + mmap_read_unlock(current->mm); + return -EFAULT; + } + + vfio_allow_any_uc = vma->vm_flags & VM_ALLOW_ANY_UNCACHED; + mte_allowed = kvm_vma_mte_allowed(vma); } if (force_pte) @@ -1590,18 +1621,13 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, ipa &= ~(vma_pagesize - 1); } - gfn = ipa >> PAGE_SHIFT; - mte_allowed = kvm_vma_mte_allowed(vma); - - vfio_allow_any_uc = vma->vm_flags & VM_ALLOW_ANY_UNCACHED; - /* Don't use the VMA after the unlock -- it may have vanished */ vma = NULL; /* * Read mmu_invalidate_seq so that KVM can detect if the results of - * vma_lookup() or __kvm_faultin_pfn() become stale prior to - * acquiring kvm->mmu_lock. + * vma_lookup() or faultin_pfn() become stale prior to acquiring + * kvm->mmu_lock. * * Rely on mmap_read_unlock() for an implicit smp_rmb(), which pairs * with the smp_wmb() in kvm_mmu_invalidate_end(). @@ -1609,8 +1635,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, mmu_seq = vcpu->kvm->mmu_invalidate_seq; mmap_read_unlock(current->mm); - pfn = __kvm_faultin_pfn(memslot, gfn, write_fault ? FOLL_WRITE : 0, - &writable, &page); + pfn = faultin_pfn(kvm, memslot, gfn, write_fault, &writable, &page, is_gmem); if (pfn == KVM_PFN_ERR_HWPOISON) { kvm_send_hwpoison_signal(hva, vma_shift); return 0; diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 3d5595a71a2a..ec3bedc18eab 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -1882,6 +1882,11 @@ static inline int memslot_id(struct kvm *kvm, gfn_t gfn) return gfn_to_memslot(kvm, gfn)->id; } +static inline bool memslot_is_readonly(const struct kvm_memory_slot *slot) +{ + return slot->flags & KVM_MEM_READONLY; +} + static inline gfn_t hva_to_gfn_memslot(unsigned long hva, struct kvm_memory_slot *slot) { diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 38f0f402ea46..3e40acb9f5c0 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2624,11 +2624,6 @@ unsigned long kvm_host_page_size(struct kvm_vcpu *vcpu, gfn_t gfn) return size; } -static bool memslot_is_readonly(const struct kvm_memory_slot *slot) -{ - return slot->flags & KVM_MEM_READONLY; -} - static unsigned long __gfn_to_hva_many(const struct kvm_memory_slot *slot, gfn_t gfn, gfn_t *nr_pages, bool write) {