[PATCH v4 8/8] x86/fpu/xstate: Warn if guest-only supervisor states are detected in normal fpstate

[Chao Gao]

From: Yang Weijiang <weijiang.yang@xxxxxxxxx>

guest-only supervisor state bits should be __ONLY__ enabled for guest
fpstate, i.e., never for normal kernel fpstate. WARN_ONCE() if normal
kernel fpstate sees any of these features.

Signed-off-by: Yang Weijiang <weijiang.yang@xxxxxxxxx>
Signed-off-by: Chao Gao <chao.gao@xxxxxxxxx>
---
 arch/x86/kernel/fpu/xstate.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/kernel/fpu/xstate.h b/arch/x86/kernel/fpu/xstate.h
index 1418423bc4c9..f644647c0549 100644
--- a/arch/x86/kernel/fpu/xstate.h
+++ b/arch/x86/kernel/fpu/xstate.h
@@ -208,6 +208,8 @@ 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_SUPERVISOR_GUEST));
+
 	XSTATE_XSAVE(&fpstate->regs.xsave, lmask, hmask, err);
 
 	/* We should never fault when copying to a kernel buffer: */
-- 
2.46.1