Re: [PATCH 1/4] x86/hyperv: Add missing ARCH_HAS_CC_PLATFORM dependency

[Kirill A. Shutemov]

On Wed, Feb 23, 2022 at 07:02:49PM +0800, Tianyu Lan wrote:
> On 2/23/2022 6:56 PM, Borislav Petkov wrote:
> > On Wed, Feb 23, 2022 at 06:43:40PM +0800, Tianyu Lan wrote:
> > > Hyper-V code check cpuid during runtime and there is no Hyper-V
> > > isolation VM option.
> > 
> > So how does "Current Hyper-V Isolation VM requires AMD_MEM_ENCRYPT" work
> > exactly?
> > 
> > Please explain in detail and not in piecemeal sentences.
> > 
> The kernel in the image needs to select AMD_MEM_ENCRYPT option
> otherwise the kernel can't boot up due to missing SEV support and
> sev_es_ghcb_hv_call() always return error.

If kernel boots under SEV, doesn't it mean we have 'sme_me_mask'
initialized? If it is non zero hv_is_isolation_supported() check in
cc_platform_has() has zero effect as it checked after 'sme_me_mask'.

I still have no idea what is going on.

How SEV related to HyperV isolation? How detection happens? Could you
give full picture?

-- 
 Kirill A. Shutemov