Re: [Xen-devel] [RFC v1 12/15] vmx: Properly handle notification event when vCPU is running

["Zhang, Yang Z" <yang.z.zhang@xxxxxxxxx>]

Wu, Feng wrote on 2015-03-25:
> When a vCPU is running in Root mode and a notification event has been
> injected to it. we need to set VCPU_KICK_SOFTIRQ for the current cpu,
> so the pending interrupt in PIRR will be synced to vIRR before VM-Exit in 
> time.

Shouldn't the pending interrupt be synced unconditionally before next vmentry? 
What happens if we didn't set the softirq?

> 
> Signed-off-by: Feng Wu <feng.wu@xxxxxxxxx>
> ---
>  xen/arch/x86/hvm/vmx/vmx.c        | 24 +++++++++++++++++++++++-
>  xen/include/asm-x86/hvm/vmx/vmx.h |  1 +
>  2 files changed, 24 insertions(+), 1 deletion(-)
> diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
> index b2b4c26..b30392c 100644 --- a/xen/arch/x86/hvm/vmx/vmx.c +++
> b/xen/arch/x86/hvm/vmx/vmx.c @@ -1838,7 +1838,7 @@ const struct
> hvm_function_table * __init start_vmx(void)
> 
>      if ( cpu_has_vmx_posted_intr_processing )
>      {
> -        alloc_direct_apic_vector(&posted_intr_vector,
> event_check_interrupt); +       
> alloc_direct_apic_vector(&posted_intr_vector, +
> pi_notification_interrupt);
> 
>          if ( iommu_intpost )
>              alloc_direct_apic_vector(&pi_wakeup_vector,
> pi_wakeup_interrupt); @@ -3288,6 +3288,28 @@ void
> pi_wakeup_interrupt(struct cpu_user_regs *regs)  }
> 
>  /*
> + * Handle VT-d posted-interrupt when VCPU is running. + */ + +void
> pi_notification_interrupt(struct cpu_user_regs *regs) { +    /* +     *
> We get here because a vCPU is running in Root mode +     * and a
> notification event has been injected to it. +     * +     * we need to
> set VCPU_KICK_SOFTIRQ for the current +     * cpu, just like
> __vmx_deliver_posted_interrupt(). +     * +     * So the pending
> interrupt in PIRR will be synced to +     * vIRR before VM-Exit in time.
> +     */ +    set_bit(VCPU_KICK_SOFTIRQ,
> &softirq_pending(smp_processor_id())); + +    ack_APIC_irq(); +   
> this_cpu(irq_count)++; +} + +/*
>   * Local variables:
>   * mode: C
>   * c-file-style: "BSD"
> diff --git a/xen/include/asm-x86/hvm/vmx/vmx.h
> b/xen/include/asm-x86/hvm/vmx/vmx.h index f4296ab..e53275b 100644 ---
> a/xen/include/asm-x86/hvm/vmx/vmx.h +++
> b/xen/include/asm-x86/hvm/vmx/vmx.h @@ -576,6 +576,7 @@ void
> free_p2m_hap_data(struct p2m_domain *p2m); void p2m_init_hap_data(struct
> p2m_domain *p2m);
> 
>  void pi_wakeup_interrupt(struct cpu_user_regs *regs);
> +void pi_notification_interrupt(struct cpu_user_regs *regs);
> 
>  /* EPT violation qualifications definitions */
>  #define _EPT_READ_VIOLATION         0


Best regards,
Yang



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