From ca2f5466f854184f1753ecb526f0e21a353a25e7 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Tue, 7 May 2019 09:06:33 -0700 Subject: [PATCH] KVM: nVMX: Don't speculatively write virtual-APIC page address The VIRTUAL_APIC_PAGE_ADDR in vmcs02 is guaranteed to be updated before it is consumed by hardware, either in nested_vmx_enter_non_root_mode() or via the KVM_REQ_GET_VMCS12_PAGES callback. Avoid an extra VMWRITE and only stuff a bad value into vmcs02 when mapping vmcs12's address fails. This also eliminates the need for extra comments to connect the dots between prepare_vmcs02_early() and nested_get_vmcs12_pages(). Signed-off-by: Sean Christopherson Signed-off-by: Paolo Bonzini --- arch/x86/kvm/vmx/nested.c | 21 ++++++++------------- 1 file changed, 8 insertions(+), 13 deletions(-) diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index 4ba0e7b60253..ded024738db4 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -2039,20 +2039,13 @@ static void prepare_vmcs02_early(struct vcpu_vmx *vmx, struct vmcs12 *vmcs12) exec_control &= ~CPU_BASED_TPR_SHADOW; exec_control |= vmcs12->cpu_based_vm_exec_control; - /* - * Write an illegal value to VIRTUAL_APIC_PAGE_ADDR. Later, if - * nested_get_vmcs12_pages can't fix it up, the illegal value - * will result in a VM entry failure. - */ - if (exec_control & CPU_BASED_TPR_SHADOW) { - vmcs_write64(VIRTUAL_APIC_PAGE_ADDR, -1ull); + if (exec_control & CPU_BASED_TPR_SHADOW) vmcs_write32(TPR_THRESHOLD, vmcs12->tpr_threshold); - } else { #ifdef CONFIG_X86_64 + else exec_control |= CPU_BASED_CR8_LOAD_EXITING | CPU_BASED_CR8_STORE_EXITING; #endif - } /* * A vmexit (to either L1 hypervisor or L0 userspace) is always needed @@ -2861,10 +2854,6 @@ static void nested_get_vmcs12_pages(struct kvm_vcpu *vcpu) if (nested_cpu_has(vmcs12, CPU_BASED_TPR_SHADOW)) { map = &vmx->nested.virtual_apic_map; - /* - * If translation failed, VM entry will fail because - * prepare_vmcs02 set VIRTUAL_APIC_PAGE_ADDR to -1ull. - */ if (!kvm_vcpu_map(vcpu, gpa_to_gfn(vmcs12->virtual_apic_page_addr), map)) { vmcs_write64(VIRTUAL_APIC_PAGE_ADDR, pfn_to_hpa(map->pfn)); } else if (nested_cpu_has(vmcs12, CPU_BASED_CR8_LOAD_EXITING) && @@ -2880,6 +2869,12 @@ static void nested_get_vmcs12_pages(struct kvm_vcpu *vcpu) */ vmcs_clear_bits(CPU_BASED_VM_EXEC_CONTROL, CPU_BASED_TPR_SHADOW); + } else { + /* + * Write an illegal value to VIRTUAL_APIC_PAGE_ADDR to + * force VM-Entry to fail. + */ + vmcs_write64(VIRTUAL_APIC_PAGE_ADDR, -1ull); } }