From 49def500e5eca40c73da9bad9799e9fab885996f Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Fri, 19 Apr 2019 22:50:56 -0700 Subject: KVM: VMX: Read cached VM-Exit reason to detect external interrupt Generic x86 code invokes the kvm_x86_ops external interrupt handler on all VM-Exits regardless of the actual exit type. Use the already-cached EXIT_REASON to determine if the VM-Exit was due to an interrupt, thus avoiding an extra VMREAD (to query VM_EXIT_INTR_INFO) for all other types of VM-Exit. In addition to avoiding the extra VMREAD, checking the EXIT_REASON instead of VM_EXIT_INTR_INFO makes it more obvious that vmx_handle_external_intr() is called for all VM-Exits, e.g. someone unfamiliar with the flow might wonder under what condition(s) VM_EXIT_INTR_INFO does not contain a valid interrupt, which is simply not possible since KVM always runs with "ack interrupt on exit". WARN once if VM_EXIT_INTR_INFO doesn't contain a valid interrupt on an EXTERNAL_INTERRUPT VM-Exit, as such a condition would indicate a hardware bug. Signed-off-by: Sean Christopherson Signed-off-by: Paolo Bonzini --- arch/x86/kvm/vmx/vmcs.h | 6 +++++ arch/x86/kvm/vmx/vmx.c | 62 ++++++++++++++++++++++++++----------------------- 2 files changed, 39 insertions(+), 29 deletions(-) diff --git a/arch/x86/kvm/vmx/vmcs.h b/arch/x86/kvm/vmx/vmcs.h index cb6079f8a227..971a46c69df4 100644 --- a/arch/x86/kvm/vmx/vmcs.h +++ b/arch/x86/kvm/vmx/vmcs.h @@ -115,6 +115,12 @@ static inline bool is_nmi(u32 intr_info) == (INTR_TYPE_NMI_INTR | INTR_INFO_VALID_MASK); } +static inline bool is_external_intr(u32 intr_info) +{ + return (intr_info & (INTR_INFO_VALID_MASK | INTR_INFO_INTR_TYPE_MASK)) + == (INTR_INFO_VALID_MASK | INTR_TYPE_EXT_INTR); +} + enum vmcs_field_width { VMCS_FIELD_WIDTH_U16 = 0, VMCS_FIELD_WIDTH_U64 = 1, diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index da6c829bad9f..b541fe2c6347 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -6127,42 +6127,46 @@ static void vmx_complete_atomic_exit(struct vcpu_vmx *vmx) static void vmx_handle_external_intr(struct kvm_vcpu *vcpu) { - u32 exit_intr_info = vmcs_read32(VM_EXIT_INTR_INFO); - - if ((exit_intr_info & (INTR_INFO_VALID_MASK | INTR_INFO_INTR_TYPE_MASK)) - == (INTR_INFO_VALID_MASK | INTR_TYPE_EXT_INTR)) { - unsigned int vector; - unsigned long entry; - gate_desc *desc; - struct vcpu_vmx *vmx = to_vmx(vcpu); + unsigned int vector; + unsigned long entry; #ifdef CONFIG_X86_64 - unsigned long tmp; + unsigned long tmp; #endif + gate_desc *desc; + u32 intr_info; - vector = exit_intr_info & INTR_INFO_VECTOR_MASK; - desc = (gate_desc *)vmx->host_idt_base + vector; - entry = gate_offset(desc); - asm volatile( + if (to_vmx(vcpu)->exit_reason != EXIT_REASON_EXTERNAL_INTERRUPT) + return; + + intr_info = vmcs_read32(VM_EXIT_INTR_INFO); + if (WARN_ONCE(!is_external_intr(intr_info), + "KVM: unexpected VM-Exit interrupt info: 0x%x", intr_info)) + return; + + vector = intr_info & INTR_INFO_VECTOR_MASK; + desc = (gate_desc *)vmx->host_idt_base + vector; + entry = gate_offset(desc); + + asm volatile( #ifdef CONFIG_X86_64 - "mov %%" _ASM_SP ", %[sp]\n\t" - "and $0xfffffffffffffff0, %%" _ASM_SP "\n\t" - "push $%c[ss]\n\t" - "push %[sp]\n\t" + "mov %%" _ASM_SP ", %[sp]\n\t" + "and $0xfffffffffffffff0, %%" _ASM_SP "\n\t" + "push $%c[ss]\n\t" + "push %[sp]\n\t" #endif - "pushf\n\t" - __ASM_SIZE(push) " $%c[cs]\n\t" - CALL_NOSPEC - : + "pushf\n\t" + __ASM_SIZE(push) " $%c[cs]\n\t" + CALL_NOSPEC + : #ifdef CONFIG_X86_64 - [sp]"=&r"(tmp), + [sp]"=&r"(tmp), #endif - ASM_CALL_CONSTRAINT - : - THUNK_TARGET(entry), - [ss]"i"(__KERNEL_DS), - [cs]"i"(__KERNEL_CS) - ); - } + ASM_CALL_CONSTRAINT + : + THUNK_TARGET(entry), + [ss]"i"(__KERNEL_DS), + [cs]"i"(__KERNEL_CS) + ); } STACK_FRAME_NON_STANDARD(vmx_handle_external_intr); -- cgit v1.2.3