diff mbox series

[6/6] x86/fpu/xstate: Warn if CET supervisor state is detected in normal fpstate

Message ID 20240531090331.13713-7-weijiang.yang@intel.com (mailing list archive)
State New, archived
Headers show
Series Introduce CET supervisor state support | expand

Commit Message

Yang, Weijiang May 31, 2024, 9:03 a.m. UTC
CET supervisor state bit is __ONLY__ enabled for guest fpstate, i.e.,
never for normal kernel fpstate. The bit is set when guest FPU config
is initialized.

For normal fpstate, the bit should have been removed when initializes
kernel FPU config settings, WARN_ONCE() if kernel detects normal fpstate
xfeatures contains CET supervisor state bit before xsaves operation.

Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
---
 arch/x86/kernel/fpu/xstate.h | 2 ++
 1 file changed, 2 insertions(+)
diff mbox series

Patch

diff --git a/arch/x86/kernel/fpu/xstate.h b/arch/x86/kernel/fpu/xstate.h
index 05df04f39628..b1b3e0fe02c6 100644
--- a/arch/x86/kernel/fpu/xstate.h
+++ b/arch/x86/kernel/fpu/xstate.h
@@ -189,6 +189,8 @@  static inline void os_xsave(struct fpstate *fpstate)
 	WARN_ON_FPU(!alternatives_patched);
 	xfd_validate_state(fpstate, mask, false);
 
+	WARN_ON_FPU(!fpstate->is_guest && (mask & XFEATURE_MASK_CET_KERNEL));
+
 	XSTATE_XSAVE(&fpstate->regs.xsave, lmask, hmask, err);
 
 	/* We should never fault when copying to a kernel buffer: */