Re: [V1 PATCH 1/3] pvh: early return from hvm_hap_nested_page_fault

[Tim Deegan <tim@xen.org>]

At 17:03 -0800 on 24 Feb (1393257835), Mukesh Rathor wrote:
> pvh does not support nested hvm at present. As such, return if pvh.

Nack, sorry.  

1: this is the nested pagefault (i.e. EPT/NPT) handler, not part of
the nested HVM code.

2: If there _is_ a problem with the interaction between nested HVM and
PVH, the right way to fix it is to enforce that they can't both be
enabled at the same time, and then make sure all the nested-HVM code
properly checks for being enabled.  It's not a good idea to scatter
PVH checks all over code for unrelated features.

Cheers,

Tim.

> Signed-off-by: Mukesh Rathor <mukesh.rathor@oracle.com>
> ---
>  xen/arch/x86/hvm/hvm.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
> index 69f7e74..a4a3dcf 100644
> --- a/xen/arch/x86/hvm/hvm.c
> +++ b/xen/arch/x86/hvm/hvm.c
> @@ -1416,6 +1416,9 @@ int hvm_hap_nested_page_fault(paddr_t gpa,
>      int sharing_enomem = 0;
>      mem_event_request_t *req_ptr = NULL;
>  
> +    if ( is_pvh_vcpu(v) )
> +        return 0;
> +
>      /* On Nested Virtualization, walk the guest page table.
>       * If this succeeds, all is fine.
>       * If this fails, inject a nested page fault into the guest.
> -- 
> 1.8.3.1
> 
> 
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