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Date: Wed, 8 Apr 2009 22:48:50 +0300
From: Gleb Natapov <gleb@...hat.com>
To: Glauber Costa <glommer@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org, avi@...hat.com,
"H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH] disable interrupt shadow state for emulated instruction
On Wed, Apr 08, 2009 at 01:57:32PM -0400, Glauber Costa wrote:
> we currently unblock shadow interrupt state when we skip an instruction,
> but failing to do so when we actually emulate one. This blocks interrupts
> in key instruction blocks, in particular sti; hlt; sequences
>
> Without this patch, I cannot boot gpxe option roms at vmx machines.
> This is described at https://bugzilla.redhat.com/show_bug.cgi?id=494469
>
> Signed-off-by: Glauber Costa <glommer@...hat.com>
> CC: H. Peter Anvin <hpa@...or.com>
> CC: Avi Kivity <avi@...hat.com>
> ---
> arch/x86/include/asm/kvm_host.h | 1 +
> arch/x86/kvm/svm.c | 12 ++++++++++--
> arch/x86/kvm/vmx.c | 29 +++++++++++++++++++----------
> arch/x86/kvm/x86.c | 2 ++
> 4 files changed, 32 insertions(+), 12 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 3fc4623..0890a6e 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -513,6 +513,7 @@ struct kvm_x86_ops {
> void (*run)(struct kvm_vcpu *vcpu, struct kvm_run *run);
> int (*handle_exit)(struct kvm_run *run, struct kvm_vcpu *vcpu);
> void (*skip_emulated_instruction)(struct kvm_vcpu *vcpu);
> + void (*block_interrupt_shadow)(struct kvm_vcpu *vcpu);
remove_interrupt_shadow or unblock_interrupt_shadow would be better
names IMHO.
> void (*patch_hypercall)(struct kvm_vcpu *vcpu,
> unsigned char *hypercall_addr);
> int (*get_irq)(struct kvm_vcpu *vcpu);
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index 3ffb695..d303e86 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -210,6 +210,14 @@ static int is_external_interrupt(u32 info)
> return info == (SVM_EVTINJ_VALID | SVM_EVTINJ_TYPE_INTR);
> }
>
> +static void svm_block_interrupt_shadow(struct kvm_vcpu *vcpu)
> +{
> + struct vcpu_svm *svm = to_svm(vcpu);
> +
> + svm->vmcb->control.int_state &= ~SVM_INTERRUPT_SHADOW_MASK;
> + vcpu->arch.interrupt_window_open = (svm->vcpu.arch.hflags & HF_GIF_MASK);
> +}
> +
> static void skip_emulated_instruction(struct kvm_vcpu *vcpu)
> {
> struct vcpu_svm *svm = to_svm(vcpu);
> @@ -223,9 +231,8 @@ static void skip_emulated_instruction(struct kvm_vcpu *vcpu)
> __func__, kvm_rip_read(vcpu), svm->next_rip);
>
> kvm_rip_write(vcpu, svm->next_rip);
> - svm->vmcb->control.int_state &= ~SVM_INTERRUPT_SHADOW_MASK;
>
> - vcpu->arch.interrupt_window_open = (svm->vcpu.arch.hflags & HF_GIF_MASK);
> + svm_block_interrupt_shadow(vcpu);
> }
>
> static int has_svm(void)
> @@ -2660,6 +2667,7 @@ static struct kvm_x86_ops svm_x86_ops = {
> .run = svm_vcpu_run,
> .handle_exit = handle_exit,
> .skip_emulated_instruction = skip_emulated_instruction,
> + .block_interrupt_shadow = svm_block_interrupt_shadow,
> .patch_hypercall = svm_patch_hypercall,
> .get_irq = svm_get_irq,
> .set_irq = svm_set_irq,
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index c6997c0..cee38e4 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -736,26 +736,34 @@ static void vmx_set_rflags(struct kvm_vcpu *vcpu, unsigned long rflags)
> vmcs_writel(GUEST_RFLAGS, rflags);
> }
>
> +static void vmx_block_interrupt_shadow(struct kvm_vcpu *vcpu)
> +{
> + /*
> + * We emulated an instruction, so temporary interrupt blocking
> + * should be removed, if set.
> + */
> + u32 interruptibility = vmcs_read32(GUEST_INTERRUPTIBILITY_INFO);
> + u32 interruptibility_mask = ((GUEST_INTR_STATE_STI | GUEST_INTR_STATE_MOV_SS));
> +
> + if (interruptibility & interruptibility_mask)
> + vmcs_write32(GUEST_INTERRUPTIBILITY_INFO,
> + interruptibility & ~interruptibility_mask);
> + vcpu->arch.interrupt_window_open = 1;
> +}
> +
> static void skip_emulated_instruction(struct kvm_vcpu *vcpu)
> {
> unsigned long rip;
> - u32 interruptibility;
>
> rip = kvm_rip_read(vcpu);
> rip += vmcs_read32(VM_EXIT_INSTRUCTION_LEN);
> kvm_rip_write(vcpu, rip);
>
> - /*
> - * We emulated an instruction, so temporary interrupt blocking
> - * should be removed, if set.
> - */
> - interruptibility = vmcs_read32(GUEST_INTERRUPTIBILITY_INFO);
> - if (interruptibility & 3)
> - vmcs_write32(GUEST_INTERRUPTIBILITY_INFO,
> - interruptibility & ~3);
> - vcpu->arch.interrupt_window_open = 1;
> + /* skipping an emulated instruction also counts */
> + vmx_block_interrupt_shadow(vcpu);
> }
>
> +
> static void vmx_queue_exception(struct kvm_vcpu *vcpu, unsigned nr,
> bool has_error_code, u32 error_code)
> {
> @@ -3727,6 +3735,7 @@ static struct kvm_x86_ops vmx_x86_ops = {
> .run = vmx_vcpu_run,
> .handle_exit = vmx_handle_exit,
> .skip_emulated_instruction = skip_emulated_instruction,
> + .block_interrupt_shadow = vmx_block_interrupt_shadow,
> .patch_hypercall = vmx_patch_hypercall,
> .get_irq = vmx_get_irq,
> .set_irq = vmx_inject_irq,
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 0bb4131..8fa83b9 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -2414,6 +2414,8 @@ int emulate_instruction(struct kvm_vcpu *vcpu,
>
> r = x86_emulate_insn(&vcpu->arch.emulate_ctxt, &emulate_ops);
>
> + kvm_x86_ops->block_interrupt_shadow(vcpu);
> +
> if (vcpu->arch.pio.string)
> return EMULATE_DO_MMIO;
>
> --
> 1.5.6.6
>
> --
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--
Gleb.
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