x86/fpu: Move XSAVE-disabling code to a helper

When we want to _completely_ disable XSAVE support as far as
the kernel is concerned, we have a big set of feature flags
to clear.  We currently only do this in cases where the user
asks for it to be disabled, but we are about to expand the
places where we do it to handle errors too.

Move the code in to xstate.c, and put it in the xstate.h
header.  We will use it in the next patch too.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: dave@sr71.net
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/20150902233124.EA9A70E5@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

3 files changed, 21 insertions, 11 deletions

diff --git a/arch/x86/include/asm/fpu/xstate.h b/arch/x86/include/asm/fpu/xstate.h
index 4656b25bb9a7..d5a9b736553c 100644
--- a/arch/x86/include/asm/fpu/xstate.h
+++ b/arch/x86/include/asm/fpu/xstate.h
@@ -40,6 +40,7 @@ extern u64 xstate_fx_sw_bytes[USER_XSTATE_FX_SW_WORDS];
 
 extern void update_regset_xstate_info(unsigned int size, u64 xstate_mask);
 
+void fpu__xstate_clear_all_cpu_caps(void);
 void *get_xsave_addr(struct xregs_state *xsave, int xstate);
 const void *get_xsave_field_ptr(int xstate_field);
 
diff --git a/arch/x86/kernel/fpu/init.c b/arch/x86/kernel/fpu/init.c
index d14e9ac3235a..0a250afc6cdf 100644
--- a/arch/x86/kernel/fpu/init.c
+++ b/arch/x86/kernel/fpu/init.c
@@ -354,17 +354,7 @@ static int __init x86_noxsave_setup(char *s)
         if (strlen(s))
                 return 0;
 
-        setup_clear_cpu_cap(X86_FEATURE_XSAVE);
-        setup_clear_cpu_cap(X86_FEATURE_XSAVEOPT);
-        setup_clear_cpu_cap(X86_FEATURE_XSAVEC);
-        setup_clear_cpu_cap(X86_FEATURE_XSAVES);
-        setup_clear_cpu_cap(X86_FEATURE_AVX);
-        setup_clear_cpu_cap(X86_FEATURE_AVX2);
-        setup_clear_cpu_cap(X86_FEATURE_AVX512F);
-        setup_clear_cpu_cap(X86_FEATURE_AVX512PF);
-        setup_clear_cpu_cap(X86_FEATURE_AVX512ER);
-        setup_clear_cpu_cap(X86_FEATURE_AVX512CD);
-        setup_clear_cpu_cap(X86_FEATURE_MPX);
+        fpu__xstate_clear_all_cpu_caps();
 
         return 1;
 }
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index b790dcbd3d2a..2ada11c0f8d7 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -39,6 +39,25 @@ static unsigned int xstate_comp_offsets[sizeof(xfeatures_mask)*8];
 static unsigned int xfeatures_nr;
 
 /*
+ * Clear all of the X86_FEATURE_* bits that are unavailable
+ * when the CPU has no XSAVE support.
+ */
+void fpu__xstate_clear_all_cpu_caps(void)
+{
+        setup_clear_cpu_cap(X86_FEATURE_XSAVE);
+        setup_clear_cpu_cap(X86_FEATURE_XSAVEOPT);
+        setup_clear_cpu_cap(X86_FEATURE_XSAVEC);
+        setup_clear_cpu_cap(X86_FEATURE_XSAVES);
+        setup_clear_cpu_cap(X86_FEATURE_AVX);
+        setup_clear_cpu_cap(X86_FEATURE_AVX2);
+        setup_clear_cpu_cap(X86_FEATURE_AVX512F);
+        setup_clear_cpu_cap(X86_FEATURE_AVX512PF);
+        setup_clear_cpu_cap(X86_FEATURE_AVX512ER);
+        setup_clear_cpu_cap(X86_FEATURE_AVX512CD);
+        setup_clear_cpu_cap(X86_FEATURE_MPX);
+}
+
+/*
  * Return whether the system supports a given xfeature.
  *
  * Also return the name of the (most advanced) feature that the caller requested: