Merge tag 'x86_urgent_for_v5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 fixes from Borislav Petkov:
 "Two more urgent FPU fixes:

   - prevent unprivileged userspace from reinitializing supervisor
     states

   - prepare init_fpstate, which is the buffer used when initializing
     FPU state, properly in case the skip-writing-state-components
     XSAVE* variants are used"

* tag 'x86_urgent_for_v5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/fpu: Make init_fpstate correct with optimized XSAVE
  x86/fpu: Preserve supervisor states in sanitize_restored_user_xstate()

1 files changed, 8 insertions, 22 deletions

diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h
index fdee23ea4e17..16bf4d4a8159 100644
--- a/arch/x86/include/asm/fpu/internal.h
+++ b/arch/x86/include/asm/fpu/internal.h
@@ -204,6 +204,14 @@ static inline void copy_fxregs_to_kernel(struct fpu *fpu)
 		asm volatile("fxsaveq %[fx]" : [fx] "=m" (fpu->state.fxsave));
 }
 
+static inline void fxsave(struct fxregs_state *fx)
+{
+	if (IS_ENABLED(CONFIG_X86_32))
+		asm volatile( "fxsave %[fx]" : [fx] "=m" (*fx));
+	else
+		asm volatile("fxsaveq %[fx]" : [fx] "=m" (*fx));
+}
+
 /* These macros all use (%edi)/(%rdi) as the single memory argument. */
 #define XSAVE		".byte " REX_PREFIX "0x0f,0xae,0x27"
 #define XSAVEOPT	".byte " REX_PREFIX "0x0f,0xae,0x37"
@@ -272,28 +280,6 @@ static inline void copy_fxregs_to_kernel(struct fpu *fpu)
  * This function is called only during boot time when x86 caps are not set
  * up and alternative can not be used yet.
  */
-static inline void copy_xregs_to_kernel_booting(struct xregs_state *xstate)
-{
-	u64 mask = xfeatures_mask_all;
-	u32 lmask = mask;
-	u32 hmask = mask >> 32;
-	int err;
-
-	WARN_ON(system_state != SYSTEM_BOOTING);
-
-	if (boot_cpu_has(X86_FEATURE_XSAVES))
-		XSTATE_OP(XSAVES, xstate, lmask, hmask, err);
-	else
-		XSTATE_OP(XSAVE, xstate, lmask, hmask, err);
-
-	/* We should never fault when copying to a kernel buffer: */
-	WARN_ON_FPU(err);
-}
-
-/*
- * This function is called only during boot time when x86 caps are not set
- * up and alternative can not be used yet.
- */
 static inline void copy_kernel_to_xregs_booting(struct xregs_state *xstate)
 {
 	u64 mask = -1;