On Wed, Nov 21, 2012 at 04:09:38PM +0800, Yang Zhang wrote:
> Ack interrupt on vmexit is required by Posted Interrupt. With it,
> when external interrupt caused vmexit, the cpu will acknowledge the
> interrupt controller and save the interrupt's vector in vmcs.
>
> There are several approaches to enable it. This patch uses a simply
> way: re-generate an interrupt via self ipi.
>
> Signed-off-by: Yang Zhang <yang.z.zhang@xxxxxxxxx>
> ---
> arch/x86/kvm/vmx.c | 11 ++++++++++-
> 1 files changed, 10 insertions(+), 1 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 7949d21..f6ef090 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -2525,7 +2525,8 @@ 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;
Always? Do it only if posted interrupts are actually available
and going to be used.
> if (adjust_vmx_controls(min, opt, MSR_IA32_VMX_EXIT_CTLS,
> &_vmexit_control) < 0)
> return -EIO;
> @@ -4457,6 +4458,14 @@ static int handle_exception(struct kvm_vcpu *vcpu)
>
> static int handle_external_interrupt(struct kvm_vcpu *vcpu)
> {
> + unsigned int vector;
> +
> + vector = vmcs_read32(VM_EXIT_INTR_INFO);
> + vector &= INTR_INFO_VECTOR_MASK;
Valid bit is guarantied to be set here?
> +
> + apic_eoi();
This is way to late. handle_external_interrupt() is called longs after
preemption and local irqs are enabled. vcpu process may be scheduled out
and apic_eoi() will not be called for a long time leaving interrupt
stuck in ISR and blocking other interrupts.
> + apic->send_IPI_self(vector);
For level interrupt this is not needed, no?
> +
> ++vcpu->stat.irq_exits;
> return 1;
> }
> --
> 1.7.1
--
Gleb.
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