Merge branch 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 fpu updates from Ingo Molnar:
 "The main changes relate to fixes between (lack of) CPUID and FPU
  detection that should only affect old or weird CPUs, by Andy
  Lutomirski"

* 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/fpu: Fix the "Giving up, no FPU found" test
  x86/fpu: Fix CPUID-less FPU detection
  x86/fpu: Fix "x86/fpu: Legacy x87 FPU detected" message
  x86/cpu: Re-apply forced caps every time CPU caps are re-read
  x86/cpu: Factor out application of forced CPU caps
  x86/cpu: Add X86_FEATURE_CPUID
  x86/fpu/xstate: Move XSAVES state init to a function

3 files changed, 23 insertions, 23 deletions

diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index de7234401275..e1114f070c2d 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -9,7 +9,6 @@
 #include <asm/fpu/regset.h>
 #include <asm/fpu/signal.h>
 #include <asm/fpu/types.h>
-#include <asm/fpu/xstate.h>
 #include <asm/traps.h>
 
 #include <linux/hardirq.h>
@@ -179,14 +178,8 @@ void fpstate_init(union fpregs_state *state)
 
 	memset(state, 0, fpu_kernel_xstate_size);
 
-	/*
-	 * XRSTORS requires that this bit is set in xcomp_bv, or
-	 * it will #GP. Make sure it is replaced after the memset().
-	 */
 	if (static_cpu_has(X86_FEATURE_XSAVES))
-		state->xsave.header.xcomp_bv = XCOMP_BV_COMPACTED_FORMAT |
-					       xfeatures_mask;
-
+		fpstate_init_xstate(&state->xsave);
 	if (static_cpu_has(X86_FEATURE_FXSR))
 		fpstate_init_fxstate(&state->fxsave);
 	else
diff --git a/arch/x86/kernel/fpu/init.c b/arch/x86/kernel/fpu/init.c
index 60dece392b3a..19bdd1bf8160 100644
--- a/arch/x86/kernel/fpu/init.c
+++ b/arch/x86/kernel/fpu/init.c
@@ -48,13 +48,7 @@ void fpu__init_cpu(void)
 	fpu__init_cpu_xstate();
 }
 
-/*
- * The earliest FPU detection code.
- *
- * Set the X86_FEATURE_FPU CPU-capability bit based on
- * trying to execute an actual sequence of FPU instructions:
- */
-static void fpu__init_system_early_generic(struct cpuinfo_x86 *c)
+static bool fpu__probe_without_cpuid(void)
 {
 	unsigned long cr0;
 	u16 fsw, fcw;
@@ -65,18 +59,25 @@ static void fpu__init_system_early_generic(struct cpuinfo_x86 *c)
 	cr0 &= ~(X86_CR0_TS | X86_CR0_EM);
 	write_cr0(cr0);
 
-	if (!test_bit(X86_FEATURE_FPU, (unsigned long *)cpu_caps_cleared)) {
-		asm volatile("fninit ; fnstsw %0 ; fnstcw %1"
-			     : "+m" (fsw), "+m" (fcw));
+	asm volatile("fninit ; fnstsw %0 ; fnstcw %1" : "+m" (fsw), "+m" (fcw));
+
+	pr_info("x86/fpu: Probing for FPU: FSW=0x%04hx FCW=0x%04hx\n", fsw, fcw);
 
-		if (fsw == 0 && (fcw & 0x103f) == 0x003f)
-			set_cpu_cap(c, X86_FEATURE_FPU);
+	return fsw == 0 && (fcw & 0x103f) == 0x003f;
+}
+
+static void fpu__init_system_early_generic(struct cpuinfo_x86 *c)
+{
+	if (!boot_cpu_has(X86_FEATURE_CPUID) &&
+	    !test_bit(X86_FEATURE_FPU, (unsigned long *)cpu_caps_cleared)) {
+		if (fpu__probe_without_cpuid())
+			setup_force_cpu_cap(X86_FEATURE_FPU);
 		else
-			clear_cpu_cap(c, X86_FEATURE_FPU);
+			setup_clear_cpu_cap(X86_FEATURE_FPU);
 	}
 
 #ifndef CONFIG_MATH_EMULATION
-	if (!boot_cpu_has(X86_FEATURE_FPU)) {
+	if (!test_cpu_cap(&boot_cpu_data, X86_FEATURE_FPU)) {
 		pr_emerg("x86/fpu: Giving up, no FPU found and no math emulation present\n");
 		for (;;)
 			asm volatile("hlt");
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index 35f7024aace5..c24ac1efb12d 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -706,8 +706,14 @@ void __init fpu__init_system_xstate(void)
 	WARN_ON_FPU(!on_boot_cpu);
 	on_boot_cpu = 0;
 
+	if (!boot_cpu_has(X86_FEATURE_FPU)) {
+		pr_info("x86/fpu: No FPU detected\n");
+		return;
+	}
+
 	if (!boot_cpu_has(X86_FEATURE_XSAVE)) {
-		pr_info("x86/fpu: Legacy x87 FPU detected.\n");
+		pr_info("x86/fpu: x87 FPU will use %s\n",
+			boot_cpu_has(X86_FEATURE_FXSR) ? "FXSAVE" : "FSAVE");
 		return;
 	}