Gleb Natapov wrote on 2013-01-23:
> On Tue, Jan 22, 2013 at 01:49:31PM +0800, Yang Zhang wrote:
>> From: Yang Zhang <[email protected]>
>>
>> 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 <[email protected]>
>> ---
>> arch/x86/include/asm/kvm_host.h | 2 + arch/x86/kvm/svm.c
>> | 6 ++++ arch/x86/kvm/vmx.c | 52
>> ++++++++++++++++++++++++++++++++++++++- arch/x86/kvm/x86.c
>> | 2 + 4 files changed, 61 insertions(+), 1 deletions(-)
>> diff --git a/arch/x86/include/asm/kvm_host.h
>> b/arch/x86/include/asm/kvm_host.h index c431b33..0b73602 100644 ---
>> a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h
>> @@ -345,6 +345,7 @@ struct kvm_vcpu_arch {
>> unsigned long cr8;
>> u32 hflags;
>> u64 efer;
>> + struct desc_ptr host_idt;
> Enough to save only host_idt.address.
>
>> u64 apic_base; struct kvm_lapic *apic; /* kernel irqchip context
>> */ unsigned long apic_attention; @@ -723,6 +724,7 @@ 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..e286600 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)
>> +{
>> + return;
>> +}
>> +
>> 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 dd2a85c..ef98392 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;
>> @@ -3933,6 +3934,7 @@ static int vmx_vcpu_setup(struct vcpu_vmx *vmx)
>>
>> vmcs_writel(CR0_GUEST_HOST_MASK, ~0UL);
>> set_cr4_guest_host_mask(vmx);
>> + native_store_idt(&vmx->vcpu.arch.host_idt);
>>
> We already call native_store_idt() in vmx_set_constant_host_state(). No
> need to do it twice. Add vcpu parameter to vmx_set_constant_host_state()
> to get idt address from there.
Sure.
>> return 0;
>> }
>> @@ -6096,6 +6098,53 @@ 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.address + vector * 16; +#else + desc =
>> (void *)vcpu->arch.host_idt.address + 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" + "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",
>> "ebx", "edx"
> ebx is not clobbered on 32bit as far as I see.
Right. ebx is not touched.
>> +#endif
>> + );
>> + }
>> +}
>> +
>> static void vmx_recover_nmi_blocking(struct vcpu_vmx *vmx) { u32
>> exit_intr_info; @@ -7363,6 +7412,7 @@ 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 1c9c834..000140b 100644
>> --- a/arch/x86/kvm/x86.c
>> +++ b/arch/x86/kvm/x86.c
>> @@ -5728,6 +5728,8 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
>> native_read_tsc());
>>
>> vcpu->mode = OUTSIDE_GUEST_MODE;
>> + kvm_x86_ops->handle_external_intr(vcpu);
>> +
> Move it after smp_wmb(). Also to be close to how real interrupt is
> injected we can set IF in eflags copy that we push on a stack in
> vmx_handle_external_intr() and get rid of local_irq_enable() here
> (adding comment about it of course). svm_handle_external_intr() will
> call local_irq_enable().
Yes, we can set IF in this case. But for non external interrupt caused vmexit,
we still need the local_irq_enable() to open interrupt.
>> smp_wmb();
>> local_irq_enable();
>> --
>> 1.7.1
>
>
> --
> Gleb.
Best regards,
Yang
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