Re: [PATCH 03/11] x86/HVM: Hardware alternate p2m support detection.

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

On 09/01/15 21:26, Ed White wrote:
> As implemented here, only supported on platforms with VMX HAP.
>
> Signed-off-by: Ed White <edmund.h.white@intel.com>
> ---
>  xen/arch/x86/hvm/hvm.c        | 8 ++++++++
>  xen/arch/x86/hvm/vmx/vmx.c    | 1 +
>  xen/include/asm-x86/hvm/hvm.h | 6 ++++++
>  3 files changed, 15 insertions(+)
>
> diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
> index bc414ff..3a7367c 100644
> --- a/xen/arch/x86/hvm/hvm.c
> +++ b/xen/arch/x86/hvm/hvm.c
> @@ -157,6 +157,9 @@ static int __init hvm_enable(void)
>      if ( !fns->pvh_supported )
>          printk(XENLOG_INFO "HVM: PVH mode not supported on this platform\n");
>  
> +    if ( !fns->altp2m_supported )
> +        printk(XENLOG_INFO "HVM: Alternate p2m mode not supported on this platform\n");
> +

I am not sure this message is particularly useful.  The PVH message
above is just transitory until PVH looses some of its restrictions.

>      /*
>       * Allow direct access to the PC debug ports 0x80 and 0xed (they are
>       * often used for I/O delays, but the vmexits simply slow things down).
> @@ -6369,6 +6372,11 @@ enum hvm_intblk nhvm_interrupt_blocked(struct vcpu *v)
>      return hvm_funcs.nhvm_intr_blocked(v);
>  }
>  
> +bool_t hvm_altp2m_supported()

I have to admit that I am somewhat uneasy about the name "altp2m", but I
can't suggest anything better at the moment.  I am all ears if anyone
else has any other suggestions.

> +{
> +    return hvm_funcs.altp2m_supported;
> +}
> +
>  /*
>   * Local variables:
>   * mode: C
> diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
> index f2554d6..931709b 100644
> --- a/xen/arch/x86/hvm/vmx/vmx.c
> +++ b/xen/arch/x86/hvm/vmx/vmx.c
> @@ -1796,6 +1796,7 @@ const struct hvm_function_table * __init start_vmx(void)
>      if ( cpu_has_vmx_ept && (cpu_has_vmx_pat || opt_force_ept) )
>      {
>          vmx_function_table.hap_supported = 1;
> +        vmx_function_table.altp2m_supported = 1;
>  
>          vmx_function_table.hap_capabilities = 0;
>  
> diff --git a/xen/include/asm-x86/hvm/hvm.h b/xen/include/asm-x86/hvm/hvm.h
> index e3d2d9a..7115a68 100644
> --- a/xen/include/asm-x86/hvm/hvm.h
> +++ b/xen/include/asm-x86/hvm/hvm.h
> @@ -94,6 +94,9 @@ struct hvm_function_table {
>      /* Necessary hardware support for PVH mode? */
>      int pvh_supported;
>  
> +    /* Necessary hardware support for alternate p2m's? */
> +    int altp2m_supported;

bool_t please.  (The adjacent examples are poor)

~Andrew

> +
>      /* Indicate HAP capabilities. */
>      int hap_capabilities;
>  
> @@ -518,6 +521,9 @@ bool_t nhvm_vmcx_hap_enabled(struct vcpu *v);
>  /* interrupt */
>  enum hvm_intblk nhvm_interrupt_blocked(struct vcpu *v);
>  
> +/* returns true if hardware supports alternate p2m's */
> +bool_t hvm_altp2m_supported(void);
> +
>  #ifndef NDEBUG
>  /* Permit use of the Forced Emulation Prefix in HVM guests */
>  extern bool_t opt_hvm_fep;