Re: [PATCH 9/9] x86/virt/tdx: Don't initialize module that doesn't support NO_RBP_MOD feature

[Nikolay Borisov]

On 16.06.24 г. 15:01 ч., Kai Huang wrote:
> Old TDX modules can clobber RBP in the TDH.VP.ENTER SEAMCALL.  However
> RBP is used as frame pointer in the x86_64 calling convention, and
> clobbering RBP could result in bad things like being unable to unwind
> the stack if any non-maskable exceptions (NMI, #MC etc) happens in that
> gap.
>
> A new "NO_RBP_MOD" feature was introduced to more recent TDX modules to
> not clobber RBP.  This feature is reported in the TDX_FEATURES0 global
> metadata field via bit 18.
>
> Don't initialize the TDX module if this feature is not supported [1].
>
> Link: https://lore.kernel.org/all/c0067319-2653-4cbd-8fee-1ccf21b1e646@xxxxxxxx/T/#mef98469c51e2382ead2c537ea189752360bd2bef [1]
> Signed-off-by: Kai Huang <kai.huang@xxxxxxxxx>

Reviewed-by: Nikolay Borisov <nik.borisov@xxxxxxxx>