On Mon, Jan 28, 2013 at 08:54:07AM +0800, Yang Zhang wrote:
> From: Yang Zhang <yang.z.zhang@xxxxxxxxx>
>
> The "acknowledge interrupt on exit" feature controls processor behavior
> for external interrupt acknowledgement. When this control is set, the
> processor acknowledges the interrupt controller to acquire the
> interrupt vector on VM exit.
>
> After enabling this feature, an interrupt which arrived when target cpu is
> running in vmx non-root mode will be handled by vmx handler instead of handler
> in idt. Currently, vmx handler only fakes an interrupt stack and jump to idt
> table to let real handler to handle it. Further, we will recognize the interrupt
> and only delivery the interrupt which not belong to current vcpu through idt table.
> The interrupt which belonged to current vcpu will be handled inside vmx handler.
> This will reduce the interrupt handle cost of KVM.
>
> Refer to Intel SDM volum 3, chapter 33.2.
>
> Signed-off-by: Yang Zhang <yang.z.zhang@xxxxxxxxx>
> ---
> arch/x86/include/asm/kvm_host.h | 2 +
> arch/x86/kvm/svm.c | 6 ++++
> arch/x86/kvm/vmx.c | 61 ++++++++++++++++++++++++++++++++++++--
> arch/x86/kvm/x86.c | 3 +-
> 4 files changed, 67 insertions(+), 5 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 77d56a4..07daf10 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -340,6 +340,7 @@ struct kvm_vcpu_arch {
> unsigned long cr8;
> u32 hflags;
> u64 efer;
> + unsigned long host_idt_base;
Should be in vmx.
> u64 apic_base;
> struct kvm_lapic *apic; /* kernel irqchip context */
> unsigned long apic_attention;
> @@ -725,6 +726,7 @@ struct kvm_x86_ops {
> int (*check_intercept)(struct kvm_vcpu *vcpu,
> struct x86_instruction_info *info,
> enum x86_intercept_stage stage);
> + void (*handle_external_intr)(struct kvm_vcpu *vcpu);
> };
>
> struct kvm_arch_async_pf {
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index d29d3cd..c283185 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -4227,6 +4227,11 @@ out:
> return ret;
> }
>
> +static void svm_handle_external_intr(struct kvm_vcpu *vcpu)
> +{
> + local_irq_enable();
> +}
> +
> static struct kvm_x86_ops svm_x86_ops = {
> .cpu_has_kvm_support = has_svm,
> .disabled_by_bios = is_disabled,
> @@ -4318,6 +4323,7 @@ static struct kvm_x86_ops svm_x86_ops = {
> .set_tdp_cr3 = set_tdp_cr3,
>
> .check_intercept = svm_check_intercept,
> + .handle_external_intr = svm_handle_external_intr,
> };
>
> static int __init svm_init(void)
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 02eeba8..243ce45 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -2565,7 +2565,8 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf)
> #ifdef CONFIG_X86_64
> min |= VM_EXIT_HOST_ADDR_SPACE_SIZE;
> #endif
> - opt = VM_EXIT_SAVE_IA32_PAT | VM_EXIT_LOAD_IA32_PAT;
> + opt = VM_EXIT_SAVE_IA32_PAT | VM_EXIT_LOAD_IA32_PAT |
> + VM_EXIT_ACK_INTR_ON_EXIT;
> if (adjust_vmx_controls(min, opt, MSR_IA32_VMX_EXIT_CTLS,
> &_vmexit_control) < 0)
> return -EIO;
> @@ -3742,7 +3743,7 @@ static void vmx_disable_intercept_for_msr(u32 msr, bool longmode_only)
> * Note that host-state that does change is set elsewhere. E.g., host-state
> * that is set differently for each CPU is set in vmx_vcpu_load(), not here.
> */
> -static void vmx_set_constant_host_state(void)
> +static void vmx_set_constant_host_state(struct kvm_vcpu *vcpu)
> {
> u32 low32, high32;
> unsigned long tmpl;
> @@ -3770,6 +3771,7 @@ static void vmx_set_constant_host_state(void)
>
> native_store_idt(&dt);
> vmcs_writel(HOST_IDTR_BASE, dt.address); /* 22.2.4 */
> + vcpu->arch.host_idt_base = dt.address;
>
> vmcs_writel(HOST_RIP, vmx_return); /* 22.2.5 */
>
> @@ -3884,7 +3886,7 @@ static int vmx_vcpu_setup(struct vcpu_vmx *vmx)
>
> vmcs_write16(HOST_FS_SELECTOR, 0); /* 22.2.4 */
> vmcs_write16(HOST_GS_SELECTOR, 0); /* 22.2.4 */
> - vmx_set_constant_host_state();
> + vmx_set_constant_host_state(&vmx->vcpu);
> #ifdef CONFIG_X86_64
> rdmsrl(MSR_FS_BASE, a);
> vmcs_writel(HOST_FS_BASE, a); /* 22.2.4 */
> @@ -6094,6 +6096,56 @@ 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;
> +
> + vector = exit_intr_info & INTR_INFO_VECTOR_MASK;
> +#ifdef CONFIG_X86_64
> + desc = (void *)vcpu->arch.host_idt_base + vector * 16;
> +#else
> + desc = (void *)vcpu->arch.host_idt_base + vector * 8;
> +#endif
> +
> + entry = gate_offset(*desc);
> + asm(
> + "mov %0, %%" _ASM_DX " \n\t"
> +#ifdef CONFIG_X86_64
> + "mov %%" _ASM_SP ", %%" _ASM_BX " \n\t"
> + "and $0xfffffffffffffff0, %%" _ASM_SP " \n\t"
> + "mov %%ss, %%" _ASM_AX " \n\t"
> + "push %%" _ASM_AX " \n\t"
> + "push %%" _ASM_BX " \n\t"
> +#endif
> + "pushf \n\t"
> + "pop %%" _ASM_AX " \n\t"
> + "or $0x200, %%" _ASM_AX " \n\t"
> + "push %%" _ASM_AX " \n\t"
> + "mov %%cs, %%" _ASM_AX " \n\t"
> + "push %%" _ASM_AX " \n\t"
> + "push intr_return \n\t"
> + "jmp *%% " _ASM_DX " \n\t"
> + "1: \n\t"
> + ".pushsection .rodata \n\t"
> + ".global intr_return \n\t"
> + "intr_return: " _ASM_PTR " 1b \n\t"
> + ".popsection \n\t"
> + : : "m"(entry) :
> +#ifdef CONFIG_X86_64
> + "rax", "rbx", "rdx"
> +#else
> + "eax", "edx"
> +#endif
> + );
> + } else
> + local_irq_enable();
> +}
> +
> static void vmx_recover_nmi_blocking(struct vcpu_vmx *vmx)
> {
> u32 exit_intr_info;
> @@ -6764,7 +6816,7 @@ static void prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
> * Other fields are different per CPU, and will be set later when
> * vmx_vcpu_load() is called, and when vmx_save_host_state() is called.
> */
> - vmx_set_constant_host_state();
> + vmx_set_constant_host_state(vcpu);
>
> /*
> * HOST_RSP is normally set correctly in vmx_vcpu_run() just before
> @@ -7361,6 +7413,7 @@ static struct kvm_x86_ops vmx_x86_ops = {
> .set_tdp_cr3 = vmx_set_cr3,
>
> .check_intercept = vmx_check_intercept,
> + .handle_external_intr = vmx_handle_external_intr,
> };
>
> static int __init vmx_init(void)
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index b9f5529..676b399 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -5767,7 +5767,8 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
>
> vcpu->mode = OUTSIDE_GUEST_MODE;
> smp_wmb();
> - local_irq_enable();
> +
I asked to add comment how interrupt is enabled here.
> + kvm_x86_ops->handle_external_intr(vcpu);
>
> ++vcpu->stat.exits;
>
> --
> 1.7.1
--
Gleb.
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