Re: [PATCHv2] x86/mm: Fix memory encryption features advertisement

[Tom Lendacky]

On 1/11/24 05:12, Kirill A. Shutemov wrote:
> When memory encryption is enabled, the kernel prints the encryption
> flavor that the system supports.
>
> The check assumes that everything is AMD SME/SEV if it doesn't have
> the TDX CPU feature set.
>
> Hyper-V vTOM sets cc_vendor to CC_VENDOR_INTEL when it runs as L2 guest
> on top of TDX, but not X86_FEATURE_TDX_GUEST. Hyper-V only needs memory
> encryption enabled for I/O without the rest of CoCo enabling.
>
> To avoid confusion, check the cc_vendor directly.
>
> Possible alternative is to completely removing the print statement.
> For a regular TDX guest, the kernel already prints a message indicating
> that it is booting on TDX. Similarly, AMD and Hyper-V can also display
> a message during their enumeration process.
>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
> Cc: Dexuan Cui <decui@xxxxxxxxxxxxx>
> Cc: Jeremi Piotrowski <jpiotrowski@xxxxxxxxxxxxxxxxxxx>

Acked-by: Tom Lendacky <thomas.lendacky@xxxxxxx>

> ---
>   arch/x86/mm/mem_encrypt.c | 56 +++++++++++++++++++++------------------
>   1 file changed, 30 insertions(+), 26 deletions(-)
>
> diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c