Re: [RFC v1 05/15] vmx: Initialize VT-d Posted-Interrupts Descriptor

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 25/03/15 12:31, Feng Wu wrote:
> This patch initializes the VT-d Posted-interrupt Descriptor.
>
> Signed-off-by: Feng Wu <feng.wu@intel.com>
> ---
>   xen/arch/x86/hvm/vmx/vmcs.c       |  3 +++
>   xen/include/asm-x86/hvm/vmx/vmx.h | 21 ++++++++++++++++++++-
>   2 files changed, 23 insertions(+), 1 deletion(-)
>
> diff --git a/xen/arch/x86/hvm/vmx/vmcs.c b/xen/arch/x86/hvm/vmx/vmcs.c
> index d614638..942f4b7 100644
> --- a/xen/arch/x86/hvm/vmx/vmcs.c
> +++ b/xen/arch/x86/hvm/vmx/vmcs.c
> @@ -1004,6 +1004,9 @@ static int construct_vmcs(struct vcpu *v)
>   
>       if ( cpu_has_vmx_posted_intr_processing )
>       {
> +        if ( iommu_intpost == 1 )

Being a boolean, please shorten this to "if ( iommu_intpost )"

> +            pi_desc_init(v);
> +
>           __vmwrite(PI_DESC_ADDR, virt_to_maddr(&v->arch.hvm_vmx.pi_desc));
>           __vmwrite(POSTED_INTR_NOTIFICATION_VECTOR, posted_intr_vector);
>       }
> diff --git a/xen/include/asm-x86/hvm/vmx/vmx.h b/xen/include/asm-x86/hvm/vmx/vmx.h
> index ecc5e17..3cd75eb 100644
> --- a/xen/include/asm-x86/hvm/vmx/vmx.h
> +++ b/xen/include/asm-x86/hvm/vmx/vmx.h
> @@ -28,6 +28,9 @@
>   #include <asm/hvm/support.h>
>   #include <asm/hvm/trace.h>
>   #include <asm/hvm/vmx/vmcs.h>
> +#include <asm/apic.h>
> +
> +extern uint8_t posted_intr_vector;
>   
>   typedef union {
>       struct {
> @@ -146,6 +149,23 @@ static inline unsigned long pi_get_pir(struct pi_desc *pi_desc, int group)
>       return xchg(&pi_desc->pir[group], 0);
>   }
>   
> +static inline void pi_desc_init(struct vcpu *v)
> +{
> +    uint32_t dest;
> +
> +    pi_clear_sn(&v->arch.hvm_vmx.pi_desc);

This is called during construct_vmcs().  You safely rely on the fact 
that all memory is safely zeroed, so you don't need this clear bit, nor 
the lower setting of ndm.

> +    v->arch.hvm_vmx.pi_desc.nv = posted_intr_vector;
> +
> +    /* Physical mode for Notificaiton Event */
> +    v->arch.hvm_vmx.pi_desc.ndm = 0;
> +    dest = cpu_physical_id(v->processor);
> +
> +    if ( x2apic_enabled )
> +        v->arch.hvm_vmx.pi_desc.ndst = dest;
> +    else
> +        v->arch.hvm_vmx.pi_desc.ndst = (dest << 8) & 0xFF00;

What takes care of ensuring that this ndst field gets updated whenever 
v->processor changes?

~Andrew

> +}
> +
>   /*
>    * Exit Reasons
>    */
> @@ -265,7 +285,6 @@ static inline unsigned long pi_get_pir(struct pi_desc *pi_desc, int group)
>   #define MODRM_EAX_ECX   ".byte 0xc1\n" /* EAX, ECX */
>   
>   extern u64 vmx_ept_vpid_cap;
> -extern uint8_t posted_intr_vector;
>   
>   #define cpu_has_vmx_ept_exec_only_supported        \
>       (vmx_ept_vpid_cap & VMX_EPT_EXEC_ONLY_SUPPORTED)