Re: [PATCH v6 04/11] x86/tdx: Add protected guest support for TDX guest

From: Kuppuswamy, Sathyanarayanan
Date: Tue Sep 28 2021 - 08:56:10 EST

On 9/28/21 4:46 AM, Joerg Roedel wrote:
On Fri, Sep 03, 2021 at 10:28:05AM -0700, Kuppuswamy Sathyanarayanan wrote:
static inline bool prot_guest_has(unsigned int attr)
if (sme_me_mask)
return amd_prot_guest_has(attr);
+ else if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL)
+ return intel_prot_guest_has(attr);

This causes a function call on every Intel machine this code runs. is
there an easier to check whether TDX is enabled, like the sme_me_mask
check on AMD?

This will only be called when CONFIG_ARCH_HAS_CC_PLATFORM is set by a platform.
So it won't be called for all platforms.

Also, intel_prot_guest_has() is a generic Intel platform branch call (so we can't
directly check for TDX here).

Sathyanarayanan Kuppuswamy
Linux Kernel Developer