diff mbox series

[v5,4/7] x86/fpu: Initialize guest FPU permissions from guest defaults

Message ID 20250410072605.2358393-5-chao.gao@intel.com (mailing list archive)
State New
Headers show
Series Introduce CET supervisor state support | expand

Commit Message

Chao Gao April 10, 2025, 7:24 a.m. UTC 
Currently, fpu->guest_perm is copied from fpu->perm, which is derived from
fpu_kernel_cfg.default_features.

Guest defaults were introduced to differentiate the features and sizes of
host and guest FPUs. Copying guest FPU permissions from the host will lead
to inconsistencies between the guest default features and permissions.

Initialize guest FPU permissions from guest defaults instead of host
defaults. This ensures that any changes to guest default features are
automatically reflected in guest permissions, which in turn guarantees
that fpstate_realloc() allocates a correctly sized XSAVE buffer for guest
FPUs.

Suggested-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Chao Gao <chao.gao@intel.com>
---
 arch/x86/kernel/fpu/core.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index 25f13cc8ad92..e23e435b85c4 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -543,8 +543,10 @@  void fpstate_reset(struct fpu *fpu)
 	fpu->perm.__state_perm		= fpu_kernel_cfg.default_features;
 	fpu->perm.__state_size		= fpu_kernel_cfg.default_size;
 	fpu->perm.__user_state_size	= fpu_user_cfg.default_size;
-	/* Same defaults for guests */
-	fpu->guest_perm = fpu->perm;
+
+	fpu->guest_perm.__state_perm	= guest_default_cfg.features;
+	fpu->guest_perm.__state_size	= guest_default_cfg.size;
+	fpu->guest_perm.__user_state_size = guest_default_cfg.user_size;
 }
 
 static inline void fpu_inherit_perms(struct fpu *dst_fpu)