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Tue, 17 Jun 2025 21:24:36 -0700 (PDT) Date: Wed, 18 Jun 2025 04:24:15 +0000 In-Reply-To: <20250618042424.330664-1-jthoughton@google.com> Mime-Version: 1.0 References: <20250618042424.330664-1-jthoughton@google.com> X-Mailer: git-send-email 2.50.0.rc2.696.g1fc2a0284f-goog Message-ID: <20250618042424.330664-7-jthoughton@google.com> Subject: [PATCH v3 06/15] KVM: arm64: Add support for KVM userfault exits From: James Houghton To: Paolo Bonzini , Sean Christopherson , Oliver Upton Cc: Jonathan Corbet , Marc Zyngier , Yan Zhao , James Houghton , Nikita Kalyazin , Anish Moorthy , Peter Gonda , Peter Xu , David Matlack , wei.w.wang@intel.com, kvm@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev Content-Type: text/plain; charset="UTF-8" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250617_212437_850732_1233159A X-CRM114-Status: GOOD ( 16.36 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org To support KVM userfault exits with arm64: 1. Force mappings to be 4K while KVM_MEM_USERFAULT is enabled. 2. Return -EFAULT when kvm_do_userfault() reports that the page is userfault (or that reading the bitmap failed). kvm_arch_commit_memory_region() was written assuming that, for KVM_MR_FLAGS_ONLY changes, KVM_MEM_LOG_DIRTY_PAGES must be being toggled. This is no longer the case, so adjust the logic appropriately. Signed-off-by: James Houghton Signed-off-by: Sean Christopherson --- arch/arm64/kvm/mmu.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index 0c209f2e1c7b2..d75a6685d6842 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c @@ -1548,7 +1548,8 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, * logging_active is guaranteed to never be true for VM_PFNMAP * memslots. */ - if (logging_active) { + if (logging_active || is_protected_kvm_enabled() || + kvm_is_userfault_memslot(memslot)) { force_pte = true; vma_shift = PAGE_SHIFT; } else { @@ -1637,6 +1638,9 @@ 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); + if (kvm_do_userfault(vcpu, &fault)) + return -EFAULT; + pfn = __kvm_faultin_pfn(memslot, fault.gfn, fault.write ? FOLL_WRITE : 0, &writable, &page); if (pfn == KVM_PFN_ERR_HWPOISON) { @@ -2134,15 +2138,19 @@ void kvm_arch_commit_memory_region(struct kvm *kvm, const struct kvm_memory_slot *new, enum kvm_mr_change change) { - bool log_dirty_pages = new && new->flags & KVM_MEM_LOG_DIRTY_PAGES; + u32 old_flags = old ? old->flags : 0; + u32 new_flags = new ? new->flags : 0; + + /* Nothing to do if not toggling dirty logging. */ + if (!((old_flags ^ new_flags) & KVM_MEM_LOG_DIRTY_PAGES)) + return; /* * At this point memslot has been committed and there is an * allocated dirty_bitmap[], dirty pages will be tracked while the * memory slot is write protected. */ - if (log_dirty_pages) { - + if (new_flags & KVM_MEM_LOG_DIRTY_PAGES) { if (change == KVM_MR_DELETE) return; -- 2.50.0.rc2.692.g299adb8693-goog