Split the asm subroutines for handling NMIs versus IRQs that occur in the guest so that the NMI handler can be called from a noinstr section. As a bonus, the NMI path doesn't need an indirect branch. Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx> --- arch/x86/kvm/vmx/vmenter.S | 70 +++++++++++++++++++++----------------- arch/x86/kvm/vmx/vmx.c | 26 ++++++-------- 2 files changed, 50 insertions(+), 46 deletions(-) diff --git a/arch/x86/kvm/vmx/vmenter.S b/arch/x86/kvm/vmx/vmenter.S index 766c6b3ef5ed..9d987e7e48c4 100644 --- a/arch/x86/kvm/vmx/vmenter.S +++ b/arch/x86/kvm/vmx/vmenter.S @@ -31,6 +31,39 @@ #define VCPU_R15 __VCPU_REGS_R15 * WORD_SIZE #endif +.macro VMX_DO_EVENT_IRQOFF call_insn call_target + /* + * Unconditionally create a stack frame, getting the correct RSP on the + * stack (for x86-64) would take two instructions anyways, and RBP can + * be used to restore RSP to make objtool happy (see below). + */ + push %_ASM_BP + mov %_ASM_SP, %_ASM_BP + +#ifdef CONFIG_X86_64 + /* + * Align RSP to a 16-byte boundary (to emulate CPU behavior) before + * creating the synthetic interrupt stack frame for the IRQ/NMI. + */ + and $-16, %rsp + push $__KERNEL_DS + push %rbp +#endif + pushf + push $__KERNEL_CS + \call_insn \call_target + + /* + * "Restore" RSP from RBP, even though IRET has already unwound RSP to + * the correct value. objtool doesn't know the callee will IRET and, + * without the explicit restore, thinks the stack is getting walloped. + * Using an unwind hint is problematic due to x86-64's dynamic alignment. + */ + mov %_ASM_BP, %_ASM_SP + pop %_ASM_BP + RET +.endm + .section .noinstr.text, "ax" /** @@ -320,35 +353,10 @@ SYM_FUNC_START(vmread_error_trampoline) SYM_FUNC_END(vmread_error_trampoline) #endif -SYM_FUNC_START(vmx_do_interrupt_nmi_irqoff) - /* - * Unconditionally create a stack frame, getting the correct RSP on the - * stack (for x86-64) would take two instructions anyways, and RBP can - * be used to restore RSP to make objtool happy (see below). - */ - push %_ASM_BP - mov %_ASM_SP, %_ASM_BP +SYM_FUNC_START(vmx_do_nmi_irqoff) + VMX_DO_EVENT_IRQOFF call asm_exc_nmi_kvm_vmx +SYM_FUNC_END(vmx_do_nmi_irqoff) -#ifdef CONFIG_X86_64 - /* - * Align RSP to a 16-byte boundary (to emulate CPU behavior) before - * creating the synthetic interrupt stack frame for the IRQ/NMI. - */ - and $-16, %rsp - push $__KERNEL_DS - push %rbp -#endif - pushf - push $__KERNEL_CS - CALL_NOSPEC _ASM_ARG1 - - /* - * "Restore" RSP from RBP, even though IRET has already unwound RSP to - * the correct value. objtool doesn't know the callee will IRET and, - * without the explicit restore, thinks the stack is getting walloped. - * Using an unwind hint is problematic due to x86-64's dynamic alignment. - */ - mov %_ASM_BP, %_ASM_SP - pop %_ASM_BP - RET -SYM_FUNC_END(vmx_do_interrupt_nmi_irqoff) +SYM_FUNC_START(vmx_do_interrupt_irqoff) + VMX_DO_EVENT_IRQOFF CALL_NOSPEC _ASM_ARG1 +SYM_FUNC_END(vmx_do_interrupt_irqoff) diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 7ace22ee240d..c242e2591896 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -6786,17 +6786,8 @@ static void vmx_apicv_post_state_restore(struct kvm_vcpu *vcpu) memset(vmx->pi_desc.pir, 0, sizeof(vmx->pi_desc.pir)); } -void vmx_do_interrupt_nmi_irqoff(unsigned long entry); - -static void handle_interrupt_nmi_irqoff(struct kvm_vcpu *vcpu, - unsigned long entry) -{ - bool is_nmi = entry == (unsigned long)asm_exc_nmi_kvm_vmx; - - kvm_before_interrupt(vcpu, is_nmi ? KVM_HANDLING_NMI : KVM_HANDLING_IRQ); - vmx_do_interrupt_nmi_irqoff(entry); - kvm_after_interrupt(vcpu); -} +void vmx_do_interrupt_irqoff(unsigned long entry); +void vmx_do_nmi_irqoff(void); static void handle_nm_fault_irqoff(struct kvm_vcpu *vcpu) { @@ -6820,7 +6811,6 @@ static void handle_nm_fault_irqoff(struct kvm_vcpu *vcpu) static void handle_exception_nmi_irqoff(struct vcpu_vmx *vmx) { - const unsigned long nmi_entry = (unsigned long)asm_exc_nmi_kvm_vmx; u32 intr_info = vmx_get_intr_info(&vmx->vcpu); /* if exit due to PF check for async PF */ @@ -6833,8 +6823,11 @@ static void handle_exception_nmi_irqoff(struct vcpu_vmx *vmx) else if (is_machine_check(intr_info)) kvm_machine_check(); /* We need to handle NMIs before interrupts are enabled */ - else if (is_nmi(intr_info)) - handle_interrupt_nmi_irqoff(&vmx->vcpu, nmi_entry); + else if (is_nmi(intr_info)) { + kvm_before_interrupt(&vmx->vcpu, KVM_HANDLING_NMI); + vmx_do_nmi_irqoff(); + kvm_after_interrupt(&vmx->vcpu); + } } static void handle_external_interrupt_irqoff(struct kvm_vcpu *vcpu) @@ -6847,7 +6840,10 @@ static void handle_external_interrupt_irqoff(struct kvm_vcpu *vcpu) "KVM: unexpected VM-Exit interrupt info: 0x%x", intr_info)) return; - handle_interrupt_nmi_irqoff(vcpu, gate_offset(desc)); + kvm_before_interrupt(vcpu, KVM_HANDLING_IRQ); + vmx_do_interrupt_irqoff(gate_offset(desc)); + kvm_after_interrupt(vcpu); + vcpu->arch.at_instruction_boundary = true; } -- 2.39.0.rc1.256.g54fd8350bd-goog