Re: [Xen-devel] [PATCH for 4.5 v2] vmx, apicv: fix save/restore issue with apicv

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 21.10.14 at 07:32, <yang.z.zhang@xxxxxxxxx> wrote:
> --- a/xen/arch/x86/hvm/vmx/vmx.c
> +++ b/xen/arch/x86/hvm/vmx/vmx.c
> @@ -1584,6 +1584,8 @@ static void vmx_process_isr(int isr, struct vcpu *v)
>  {
>      unsigned long status;
>      u8 old;
> +    unsigned int i, vector;

I don't really see the need for two variables here - just "i" would
seem to suffice.

> +    struct vlapic *vlapic = vcpu_vlapic(v);

const?

> @@ -1597,6 +1599,28 @@ static void vmx_process_isr(int isr, struct vcpu *v)
>          status |= isr << VMX_GUEST_INTR_STATUS_SVI_OFFSET;
>          __vmwrite(GUEST_INTR_STATUS, status);
>      }
> +
> +    /*
> +     * Theoretically, only level triggered interrupts can have their
> +     * corresponding bits set in the eoi exit bitmap. That is, the bits
> +     * set in the eoi exit bitmap should also be set in TMR. But a periodic
> +     * timer interrupt does not follow the rule: it is edge triggered, but
> +     * requires its corresponding bit be set in the eoi exit bitmap. So we
> +     * should not construct the eoi exit bitmap based on TMR.
> +     * Here we will construct the eoi exit bitmap via (IRR | ISR). This
> +     * means that EOIs to the interrupts that are set in the IRR or ISR will
> +     * cause VM exits after restoring, regardless of the trigger modes. It
> +     * is acceptable because the subsequent interrupts will set up the eoi
> +     * bitmap correctly.
> +     */
> +    for ( vector = 0x10; vector < NR_VECTORS; vector++ )
> +        if ( vlapic_test_vector(vector, &vlapic->regs->data[APIC_IRR]) ||
> +             vlapic_test_vector(vector, &vlapic->regs->data[APIC_ISR]) )
> +            set_bit(vector,  v->arch.hvm_vmx.eoi_exit_bitmap);
> +
> +    for ( i = 0; i < 4; i++ )

ARRAY_SIZE(v->arch.hvm_vmx.eoi_exit_bitmap) instead of 4 please,
like already done in construct_vmcs().

> +        __vmwrite(EOI_EXIT_BITMAP(i), v->arch.hvm_vmx.eoi_exit_bitmap[i]);
> +
>      vmx_vmcs_exit(v);
>  }
>  
> --- a/xen/include/asm-x86/hvm/vlapic.h
> +++ b/xen/include/asm-x86/hvm/vlapic.h
> @@ -61,6 +61,8 @@
>  
>  #define VEC_POS(v) ((v) % 32)
>  #define REG_POS(v) (((v) / 32) * 0x10)
> +#define vlapic_test_vector(vec, bitmap)                                 \
> +    test_bit(VEC_POS(vec), (uint32_t *)((bitmap) + REG_POS(vec)))

Don't cast away possible const-ness here.

But of course if there are no other needs to change the patch I could
take care of all of these while committing.

Jan


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