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>

diff --git a/arch/x86/include/asm/fpu/xstate.h b/arch/x86/include/asm/fpu/xstate.h
index 4656b25bb9a7b4a7fa719213451324b2d3f6ebec..d5a9b736553cc99c4e15ae5a73754a082cd1a94c 100644 (file)
--- 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 d14e9ac3235a1ac73174ffb95b2990d5163d2933..0a250afc6cdf5f6710ab0a7969e8b3a35cf9963b 100644 (file)
--- 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 b790dcbd3d2a43f17dd426295c15e793b0960eba..2ada11c0f8d76c211e627b2dcdb63c64079737eb 100644 (file)
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -38,6 +38,25 @@ static unsigned int xstate_comp_offsets[sizeof(xfeatures_mask)*8];
 /* The number of supported xfeatures in xfeatures_mask: */
 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.
  *