x86/fpu/xstate: Fix last_good_offset in setup_xstate_features()

The function setup_xstate_features() uses CPUID to find each xfeature's
standard-format offset and size.  Since XSAVES always uses the compacted
format, supervisor xstates are *NEVER* in the standard-format and their
offsets are left as -1's.  However, they are still being tracked as
last_good_offset.

Fix it by tracking only user xstate offsets.

 [ bp: Use xfeature_is_supervisor() and save an indentation level. Drop
   now unused xfeature_is_user(). ]

Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lkml.kernel.org/r/20200109211452.27369-2-yu-cheng.yu@intel.com

diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index a1806598aaa45924ede65d16184361ff178b1cf4..fe67cabfb4a1ca93305de59f121092a44da7bd3e 100644 (file)
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -120,11 +120,6 @@ static bool xfeature_is_supervisor(int xfeature_nr)
        return ecx & 1;
 }
 
-static bool xfeature_is_user(int xfeature_nr)
-{
-       return !xfeature_is_supervisor(xfeature_nr);
-}
-
 /*
  * When executing XSAVEOPT (or other optimized XSAVE instructions), if
  * a processor implementation detects that an FPU state component is still
@@ -265,21 +260,25 @@ static void __init setup_xstate_features(void)
 
                cpuid_count(XSTATE_CPUID, i, &eax, &ebx, &ecx, &edx);
 
+               xstate_sizes[i] = eax;
+
                /*
-                * If an xfeature is supervisor state, the offset
-                * in EBX is invalid. We leave it to -1.
+                * If an xfeature is supervisor state, the offset in EBX is
+                * invalid, leave it to -1.
                 */
-               if (xfeature_is_user(i))
-                       xstate_offsets[i] = ebx;
+               if (xfeature_is_supervisor(i))
+                       continue;
+
+               xstate_offsets[i] = ebx;
 
-               xstate_sizes[i] = eax;
                /*
-                * In our xstate size checks, we assume that the
-                * highest-numbered xstate feature has the
-                * highest offset in the buffer.  Ensure it does.
+                * In our xstate size checks, we assume that the highest-numbered
+                * xstate feature has the highest offset in the buffer.  Ensure
+                * it does.
                 */
                WARN_ONCE(last_good_offset > xstate_offsets[i],
-                       "x86/fpu: misordered xstate at %d\n", last_good_offset);
+                         "x86/fpu: misordered xstate at %d\n", last_good_offset);
+
                last_good_offset = xstate_offsets[i];
        }
 }