[PATCH V1 3/6] xen/virtio: Add option to restrict memory access under Xen

[Juergen Gross]

On 24.04.22 18:53, Oleksandr wrote:
> 
> On 23.04.22 19:40, Christoph Hellwig wrote:
> 
> 
> Hello Christoph
> 
>> Please split this into one patch that creates grant-dma-ops, and another
>> that sets up the virtio restricted access helpers.
> 
> 
> Sounds reasonable, will do:
> 
> 1. grant-dma-ops.c with config XEN_GRANT_DMA_OPS
> 
> 2. arch_has_restricted_virtio_memory_access() with config XEN_VIRTIO
> 
> 
>>
>>> +
>>> +#ifdef CONFIG_ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS
>>> +int arch_has_restricted_virtio_memory_access(void)
>>> +{
>>> +    return (xen_has_restricted_virtio_memory_access() ||
>>> +            cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT));
>>> +}
>> So instead of hardcoding Xen here, this seems like a candidate for
>> another cc_platform_has flag.
> 
> 
> I have a limited knowledge of x86 and Xen on x86.
> 
> Would the Xen specific bits fit into Confidential Computing Platform checks? I 
> will let Juergen/Boris comment on this.

I don't think cc_platform_has would be correct here. Xen certainly
provides more isolation between guests and dom0, but "Confidential
Computing" is basically orthogonal to that feature.


Juergen
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