Kai Huang 6f5c71cc42 x86/virt/tdx: Require the module to assert it has the NO_RBP_MOD mitigation ...

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.  KVM will need to use the TDH.VP.ENTER SEAMCALL to run
TDX guests.  It won't be safe to run TDX guests w/o this feature.  To
prevent it, just don't initialize the TDX module if this feature is not
supported [1].

Note the bit definitions of TDX_FEATURES0 are not auto-generated in
tdx_global_metadata.h.  Manually define a macro for it in "tdx.h".

Signed-off-by: Kai Huang <kai.huang@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Nikolay Borisov <nik.borisov@suse.com>
Reviewed-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Link: https://lore.kernel.org/fc0e8ab7-86d4-4428-be31-82e1ece6dd21@intel.com/ [1]
Link: https://lore.kernel.org/all/76ae5025502c84d799e3a56a6fc4f69a82da8f93.1734188033.git.kai.huang%40intel.com

2024-12-18 14:36:02 -08:00

..

tdx

x86/virt/tdx: Require the module to assert it has the NO_RBP_MOD mitigation

2024-12-18 14:36:02 -08:00

Makefile

x86/virt/tdx: Wire up basic SEAMCALL functions

2023-09-12 16:30:27 -07:00