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AJvYcCUxMhf074OjdpZElZ25zrGLLwvYzFshI1aianaqrRUePOfPVjnPuKmi84SUz0SHZ6I4EeRoeQs=@lists.linux.dev X-Gm-Message-State: AOJu0YyrfdxMdQWIxYaVFn4zVNGj1WapjLXS75Gr9zcb8euFxtvD/wmw y+C0fqVCAyN1efMSboxphx8mxs1WJeiPMTXaptdw1yae4ZYdOevMDFSOkk8NHG2BJdsnXroxCY+ 5dA== X-Google-Smtp-Source: AGHT+IFEQMKlxKburE51y6GhQarWMnzICIinMsy7I+cfQuk/XM9cfoW4n7svU1NRfYeSI+HbNpHGVG3xCA== X-Received: from wmsr5.prod.google.com ([2002:a05:600c:8b05:b0:456:15bd:a297]) (user=tabba job=prod-delivery.src-stubby-dispatcher) by 2002:a05:600c:64ce:b0:453:5a04:b60e with SMTP id 5b1f17b1804b1-4562e37c11fmr60337995e9.26.1752769667737; Thu, 17 Jul 2025 09:27:47 -0700 (PDT) Date: Thu, 17 Jul 2025 17:27:25 +0100 In-Reply-To: <20250717162731.446579-1-tabba@google.com> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250717162731.446579-1-tabba@google.com> X-Mailer: git-send-email 2.50.0.727.gbf7dc18ff4-goog Message-ID: <20250717162731.446579-16-tabba@google.com> Subject: [PATCH v15 15/21] KVM: arm64: Refactor user_mem_abort() 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" Refactor user_mem_abort() to improve code clarity and simplify assumptions within the function. Key changes include: * Immediately set force_pte to true at the beginning of the function if logging_active is true. This simplifies the flow and makes the condition for forcing a PTE more explicit. * Remove the misleading comment stating that logging_active is guaranteed to never be true for VM_PFNMAP memslots, as this assertion is not entirely correct. * Extract reusable code blocks into new helper functions: * prepare_mmu_memcache(): Encapsulates the logic for preparing and topping up the MMU page cache. * adjust_nested_fault_perms(): Isolates the adjustments to shadow S2 permissions and the encoding of nested translation levels. * Update min(a, (long)b) to min_t(long, a, b) for better type safety and consistency. * Perform other minor tidying up of the code. These changes primarily aim to simplify user_mem_abort() and make its logic easier to understand and maintain, setting the stage for future modifications. Reviewed-by: Gavin Shan Reviewed-by: Marc Zyngier Signed-off-by: Fuad Tabba --- arch/arm64/kvm/mmu.c | 110 +++++++++++++++++++++++-------------------- 1 file changed, 59 insertions(+), 51 deletions(-) diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index 2942ec92c5a4..b3eacb400fab 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c @@ -1470,13 +1470,56 @@ static bool kvm_vma_mte_allowed(struct vm_area_struct *vma) return vma->vm_flags & VM_MTE_ALLOWED; } +static int prepare_mmu_memcache(struct kvm_vcpu *vcpu, bool topup_memcache, + void **memcache) +{ + int min_pages; + + if (!is_protected_kvm_enabled()) + *memcache = &vcpu->arch.mmu_page_cache; + else + *memcache = &vcpu->arch.pkvm_memcache; + + if (!topup_memcache) + return 0; + + min_pages = kvm_mmu_cache_min_pages(vcpu->arch.hw_mmu); + + if (!is_protected_kvm_enabled()) + return kvm_mmu_topup_memory_cache(*memcache, min_pages); + + return topup_hyp_memcache(*memcache, min_pages); +} + +/* + * Potentially reduce shadow S2 permissions to match the guest's own S2. For + * exec faults, we'd only reach this point if the guest actually allowed it (see + * kvm_s2_handle_perm_fault). + * + * Also encode the level of the original translation in the SW bits of the leaf + * entry as a proxy for the span of that translation. This will be retrieved on + * TLB invalidation from the guest and used to limit the invalidation scope if a + * TTL hint or a range isn't provided. + */ +static void adjust_nested_fault_perms(struct kvm_s2_trans *nested, + enum kvm_pgtable_prot *prot, + bool *writable) +{ + *writable &= kvm_s2_trans_writable(nested); + if (!kvm_s2_trans_readable(nested)) + *prot &= ~KVM_PGTABLE_PROT_R; + + *prot |= kvm_encode_nested_level(nested); +} + 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, bool fault_is_perm) { int ret = 0; - bool write_fault, writable, force_pte = false; + bool topup_memcache; + bool write_fault, writable; bool exec_fault, mte_allowed; bool device = false, vfio_allow_any_uc = false; unsigned long mmu_seq; @@ -1488,6 +1531,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, gfn_t gfn; kvm_pfn_t pfn; bool logging_active = memslot_is_logging(memslot); + bool force_pte = logging_active; long vma_pagesize, fault_granule; enum kvm_pgtable_prot prot = KVM_PGTABLE_PROT_R; struct kvm_pgtable *pgt; @@ -1498,17 +1542,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, fault_granule = kvm_vcpu_trap_get_perm_fault_granule(vcpu); write_fault = kvm_is_write_fault(vcpu); exec_fault = kvm_vcpu_trap_is_exec_fault(vcpu); - VM_BUG_ON(write_fault && exec_fault); - - if (fault_is_perm && !write_fault && !exec_fault) { - kvm_err("Unexpected L2 read permission error\n"); - return -EFAULT; - } - - if (!is_protected_kvm_enabled()) - memcache = &vcpu->arch.mmu_page_cache; - else - memcache = &vcpu->arch.pkvm_memcache; + VM_WARN_ON_ONCE(write_fault && exec_fault); /* * Permission faults just need to update the existing leaf entry, @@ -1516,17 +1550,10 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, * only exception to this is when dirty logging is enabled at runtime * and a write fault needs to collapse a block entry into a table. */ - if (!fault_is_perm || (logging_active && write_fault)) { - int min_pages = kvm_mmu_cache_min_pages(vcpu->arch.hw_mmu); - - if (!is_protected_kvm_enabled()) - ret = kvm_mmu_topup_memory_cache(memcache, min_pages); - else - ret = topup_hyp_memcache(memcache, min_pages); - - if (ret) - return ret; - } + topup_memcache = !fault_is_perm || (logging_active && write_fault); + ret = prepare_mmu_memcache(vcpu, topup_memcache, &memcache); + if (ret) + return ret; /* * Let's check if we will get back a huge page backed by hugetlbfs, or @@ -1540,16 +1567,10 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, return -EFAULT; } - /* - * logging_active is guaranteed to never be true for VM_PFNMAP - * memslots. - */ - if (logging_active) { - force_pte = true; + if (force_pte) vma_shift = PAGE_SHIFT; - } else { + else vma_shift = get_vma_page_shift(vma, hva); - } switch (vma_shift) { #ifndef __PAGETABLE_PMD_FOLDED @@ -1601,7 +1622,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, max_map_size = PAGE_SIZE; force_pte = (max_map_size == PAGE_SIZE); - vma_pagesize = min(vma_pagesize, (long)max_map_size); + vma_pagesize = min_t(long, vma_pagesize, max_map_size); } /* @@ -1630,7 +1651,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, * Rely on mmap_read_unlock() for an implicit smp_rmb(), which pairs * with the smp_wmb() in kvm_mmu_invalidate_end(). */ - mmu_seq = vcpu->kvm->mmu_invalidate_seq; + mmu_seq = kvm->mmu_invalidate_seq; mmap_read_unlock(current->mm); pfn = __kvm_faultin_pfn(memslot, gfn, write_fault ? FOLL_WRITE : 0, @@ -1665,24 +1686,8 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, if (exec_fault && device) return -ENOEXEC; - /* - * Potentially reduce shadow S2 permissions to match the guest's own - * S2. For exec faults, we'd only reach this point if the guest - * actually allowed it (see kvm_s2_handle_perm_fault). - * - * Also encode the level of the original translation in the SW bits - * of the leaf entry as a proxy for the span of that translation. - * This will be retrieved on TLB invalidation from the guest and - * used to limit the invalidation scope if a TTL hint or a range - * isn't provided. - */ - if (nested) { - writable &= kvm_s2_trans_writable(nested); - if (!kvm_s2_trans_readable(nested)) - prot &= ~KVM_PGTABLE_PROT_R; - - prot |= kvm_encode_nested_level(nested); - } + if (nested) + adjust_nested_fault_perms(nested, &prot, &writable); kvm_fault_lock(kvm); pgt = vcpu->arch.hw_mmu->pgt; @@ -1953,6 +1958,9 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu) goto out_unlock; } + VM_WARN_ON_ONCE(kvm_vcpu_trap_is_permission_fault(vcpu) && + !write_fault && !kvm_vcpu_trap_is_exec_fault(vcpu)); + ret = user_mem_abort(vcpu, fault_ipa, nested, memslot, hva, esr_fsc_is_permission_fault(esr)); if (ret == 0) -- 2.50.0.727.gbf7dc18ff4-goog