[PATCH v13 51/85] KVM: VMX: Use __kvm_faultin_page() to get APIC access page/pfn
From: Sean Christopherson <seanjc@google.com>
Date: 2024-10-10 18:26:42
Also in:
kvm, kvm-riscv, kvmarm, linux-arm-kernel, linux-mips, linux-riscv, lkml, loongarch
Subsystem:
kernel virtual machine for x86 (kvm/x86), the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Sean Christopherson, Paolo Bonzini, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
Use __kvm_faultin_page() get the APIC access page so that KVM can precisely release the refcounted page, i.e. to remove yet another user of kvm_pfn_to_refcounted_page(). While the path isn't handling a guest page fault, the semantics are effectively the same; KVM just happens to be mapping the pfn into a VMCS field instead of a secondary MMU. Tested-by: Alex Bennée <redacted> Signed-off-by: Sean Christopherson <seanjc@google.com> --- arch/x86/kvm/vmx/vmx.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 851be0820e04..44cc25dfebba 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c@@ -6790,8 +6790,10 @@ void vmx_set_apic_access_page_addr(struct kvm_vcpu *vcpu) struct kvm *kvm = vcpu->kvm; struct kvm_memslots *slots = kvm_memslots(kvm); struct kvm_memory_slot *slot; + struct page *refcounted_page; unsigned long mmu_seq; kvm_pfn_t pfn; + bool writable; /* Defer reload until vmcs01 is the current VMCS. */ if (is_guest_mode(vcpu)) {
@@ -6827,7 +6829,7 @@ void vmx_set_apic_access_page_addr(struct kvm_vcpu *vcpu) * controls the APIC-access page memslot, and only deletes the memslot * if APICv is permanently inhibited, i.e. the memslot won't reappear. */ - pfn = gfn_to_pfn_memslot(slot, gfn); + pfn = __kvm_faultin_pfn(slot, gfn, FOLL_WRITE, &writable, &refcounted_page); if (is_error_noslot_pfn(pfn)) return;
@@ -6838,10 +6840,13 @@ void vmx_set_apic_access_page_addr(struct kvm_vcpu *vcpu) vmcs_write64(APIC_ACCESS_ADDR, pfn_to_hpa(pfn)); /* - * Do not pin apic access page in memory, the MMU notifier - * will call us again if it is migrated or swapped out. + * Do not pin the APIC access page in memory so that it can be freely + * migrated, the MMU notifier will call us again if it is migrated or + * swapped out. KVM backs the memslot with anonymous memory, the pfn + * should always point at a refcounted page (if the pfn is valid). */ - kvm_release_pfn_clean(pfn); + if (!WARN_ON_ONCE(!refcounted_page)) + kvm_release_page_clean(refcounted_page); /* * No need for a manual TLB flush at this point, KVM has already done a
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2.47.0.rc1.288.g06298d1525-goog