Gleb Natapov wrote on 2013-01-28:
> 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.
Sure.
>> 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.
Sorry, missed it.
>> + kvm_x86_ops->handle_external_intr(vcpu);
>>
>> ++vcpu->stat.exits;
>> --
>> 1.7.1
>
> --
> Gleb.
> --
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Best regards,
Yang
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