Re: [Xen-devel] [PATCH v2 4/4] x86/nvmx: update exit bitmap when using virtual interrupt delivery

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

> From: Roger Pau Monne <roger.pau@xxxxxxxxxx>
> Sent: Wednesday, March 25, 2020 6:19 PM
> 
> Force an update of the EOI exit bitmap in nvmx_update_apicv, because
> the one performed in vmx_intr_assist might not be reached if the
> interrupt is intercepted by nvmx_intr_intercept returning true.
> 
> Extract the code to update the exit bitmap from vmx_intr_assist into a
> helper and use it in nvmx_update_apicv.
> 
> Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> ---
> Changes since v1:
>  - Reword commit message.
> ---
>  xen/arch/x86/hvm/vmx/intr.c       | 21 +++++++++++++--------
>  xen/arch/x86/hvm/vmx/vvmx.c       |  2 ++
>  xen/include/asm-x86/hvm/vmx/vmx.h |  2 ++
>  3 files changed, 17 insertions(+), 8 deletions(-)
> 
> diff --git a/xen/arch/x86/hvm/vmx/intr.c b/xen/arch/x86/hvm/vmx/intr.c
> index 49a1295f09..000e14af49 100644
> --- a/xen/arch/x86/hvm/vmx/intr.c
> +++ b/xen/arch/x86/hvm/vmx/intr.c
> @@ -224,6 +224,18 @@ static int nvmx_intr_intercept(struct vcpu *v, struct
> hvm_intack intack)
>      return 0;
>  }
> 
> +void vmx_sync_exit_bitmap(struct vcpu *v)
> +{
> +    const unsigned int n = ARRAY_SIZE(v->arch.hvm.vmx.eoi_exit_bitmap);
> +    unsigned int i;
> +
> +    while ( (i = find_first_bit(&v->arch.hvm.vmx.eoi_exitmap_changed, n)) <
> n )
> +    {
> +        clear_bit(i, &v->arch.hvm.vmx.eoi_exitmap_changed);
> +        __vmwrite(EOI_EXIT_BITMAP(i), v->arch.hvm.vmx.eoi_exit_bitmap[i]);
> +    }
> +}
> +
>  void vmx_intr_assist(void)
>  {
>      struct hvm_intack intack;
> @@ -318,7 +330,6 @@ void vmx_intr_assist(void)
>                intack.source != hvm_intsrc_vector )
>      {
>          unsigned long status;
> -        unsigned int i, n;
> 
>         /*
>          * intack.vector is the highest priority vector. So we set 
> eoi_exit_bitmap
> @@ -379,13 +390,7 @@ void vmx_intr_assist(void)
>                      intack.vector;
>          __vmwrite(GUEST_INTR_STATUS, status);
> 
> -        n = ARRAY_SIZE(v->arch.hvm.vmx.eoi_exit_bitmap);
> -        while ( (i = find_first_bit(&v->arch.hvm.vmx.eoi_exitmap_changed,
> -                                    n)) < n )
> -        {
> -            clear_bit(i, &v->arch.hvm.vmx.eoi_exitmap_changed);
> -            __vmwrite(EOI_EXIT_BITMAP(i), 
> v->arch.hvm.vmx.eoi_exit_bitmap[i]);
> -        }
> +        vmx_sync_exit_bitmap(v);
> 
>          pt_intr_post(v, intack);
>      }
> diff --git a/xen/arch/x86/hvm/vmx/vvmx.c b/xen/arch/x86/hvm/vmx/vvmx.c
> index 8431c912a1..845dd87f75 100644
> --- a/xen/arch/x86/hvm/vmx/vvmx.c
> +++ b/xen/arch/x86/hvm/vmx/vvmx.c
> @@ -1418,6 +1418,8 @@ static void nvmx_update_apicv(struct vcpu *v)
>          status |= rvi & VMX_GUEST_INTR_STATUS_SUBFIELD_BITMASK;
>          __vmwrite(GUEST_INTR_STATUS, status);
>      }
> +
> +    vmx_sync_exit_bitmap(v);

Similarly, I'd like to do the sync within the conditional block, when intr
status is actually changed. Otherwise, it becomes checking bitmap change
in every vmentry when apicv is enabled.

>  }
> 
>  static void virtual_vmexit(struct cpu_user_regs *regs)
> diff --git a/xen/include/asm-x86/hvm/vmx/vmx.h b/xen/include/asm-
> x86/hvm/vmx/vmx.h
> index b334e1ec94..111ccd7e61 100644
> --- a/xen/include/asm-x86/hvm/vmx/vmx.h
> +++ b/xen/include/asm-x86/hvm/vmx/vmx.h
> @@ -610,6 +610,8 @@ void update_guest_eip(void);
>  void vmx_pi_per_cpu_init(unsigned int cpu);
>  void vmx_pi_desc_fixup(unsigned int cpu);
> 
> +void vmx_sync_exit_bitmap(struct vcpu *v);
> +
>  #ifdef CONFIG_HVM
>  void vmx_pi_hooks_assign(struct domain *d);
>  void vmx_pi_hooks_deassign(struct domain *d);
> --
> 2.26.0