Re: [PATCHv6 10/30] x86/tdx: Handle CPUID via #VE

Thomas Gleixner
2022-03-17T11:32:11Z

On Wed, Mar 16 2022 at 05:08, Kirill A. Shutemov wrote:
> In TDX guests, most CPUID leaf/sub-leaf combinations are virtualized
> by the TDX module while some trigger #VE.
>
> Implement the #VE handling for EXIT_REASON_CPUID by handing it through
> the hypercall, which in turn lets the TDX module handle it by invoking
> the host VMM.
>
> More details on CPUID Virtualization can be found in the TDX module
> specification, the section titled "CPUID Virtualization".
>
> Note that VMM that handles the hypercall is not trusted. It can return
> data that may steer the guest kernel in wrong direct. Only allow VMM
> to control range reserved for hypervisor communication.
>
> Return all-zeros for any CPUID outside the hypervisor range. It matches
> CPU behaviour for non-supported leaf.
>
> Co-developed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
> Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
> Reviewed-by: Andi Kleen <ak@linux.intel.com>
> Reviewed-by: Tony Luck <tony.luck@intel.com>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>

Reviewed-by: Thomas Gleixner <tglx@linutronix.de>