[PATCH 078/208] x86/fpu: Print supported xstate features in human readable way

Ingo Molnar
2015-05-05T16:30:06Z

Inform the user/admin about which xstate features the kernel supports.

Reviewed-by: Borislav Petkov <bp@alien8.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/kernel/fpu/xsave.c | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)

diff --git a/arch/x86/kernel/fpu/xsave.c b/arch/x86/kernel/fpu/xsave.c
index bfe92f73bf86..f39882b7281b 100644
--- a/arch/x86/kernel/fpu/xsave.c
+++ b/arch/x86/kernel/fpu/xsave.c
@@ -482,6 +482,30 @@ static void __init setup_xstate_features(void)
} while (1);
}

+static void print_xstate_feature(u64 xstate_mask, const char *desc)
+{
+ if (pcntxt_mask & xstate_mask) {
+ int xstate_feature = fls64(xstate_mask)-1;
+
+ pr_info("x86/fpu: Supporting XSAVE feature %2d: '%s'\n", xstate_feature, desc);
+ }
+}
+
+/*
+ * Print out all the supported xstate features:
+ */
+static void print_xstate_features(void)
+{
+ print_xstate_feature(XSTATE_FP, "x87 floating point registers");
+ print_xstate_feature(XSTATE_SSE, "SSE registers");
+ print_xstate_feature(XSTATE_YMM, "AVX registers");
+ print_xstate_feature(XSTATE_BNDREGS, "MPX bounds registers");
+ print_xstate_feature(XSTATE_BNDCSR, "MPX CSR");
+ print_xstate_feature(XSTATE_OPMASK, "AVX-512 opmask");
+ print_xstate_feature(XSTATE_ZMM_Hi256, "AVX-512 Hi256");
+ print_xstate_feature(XSTATE_Hi16_ZMM, "AVX-512 ZMM_Hi256");
+}
+
/*
* This function sets up offsets and sizes of all extended states in
* xsave area. This supports both standard format and compacted format
@@ -545,6 +569,7 @@ static void __init setup_init_fpu_buf(void)
return;

setup_xstate_features();
+ print_xstate_features();

if (cpu_has_xsaves) {
init_xstate_buf->xsave_hdr.xcomp_bv =
--
2.1.0