Re: [PATCHv5 27/30] x86/kvm: Use bounce buffers for TD guest

[Christoph Hellwig]

On Thu, Mar 10, 2022 at 08:29:01AM -0600, Tom Lendacky wrote:
> > void __init mem_encrypt_init(void)
> > {
> >          if (!cc_platform_has(CC_ATTR_MEM_ENCRYPT))
> 
> If you make this cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT), then it should
> work for both, I would think. If you use CC_ATTR_MEM_ENCRYPT, you'll force
> bare-metal SME to always use bounce buffers when doing I/O. But SME can do
> I/O to encrypted memory if the device supports 64-bit DMA or if the IOMMU is
> being used, so we don't want to force SWIOTLB in this case.

http://git.infradead.org/users/hch/misc.git/commitdiff/18b0547fe0467cb48e64ee403f50f2587fe04e3a