Re: [Xen-devel] [PATCH v3 4/4] xen: expose that grant table mappings update the IOMMU

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On 26/05/14 11:49, Jan Beulich wrote:
>>>> On 23.05.14 at 18:33, <roger.pau@xxxxxxxxxx> wrote:
>> Add a new XENFEAT_hvm_gntmap_supports_iommu that is used to check
>> whether the hypervisor properly updates the IOMMU on auto-translated
>> guests when doing a grant table map/unmap operation.
> 
> As said before, if this is indeed HVM-only (I assume PVH is being
> implied here), this should be exposed via the new CPUID leaf
> rather than via the feature map.

OK, I've been looking into this, but it seems that for PVH cpuid is
limited to 2 leafs only, so hvm_hypervisor_cpuid_leaf is never called.
Will look into expanding this, but then I should probably add some
checks to prevent PVH guests from reporting either
XEN_HVM_CPUID_APIC_ACCESS_VIRT or XEN_HVM_CPUID_X2APIC_VIRT for the time
being.

Roger.


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