x86/fpu: Remove fpstate_xstate_init_size() boot quirk

fpstate_xstate_init_size() is called in fpu__cpu_init(), which is
run on every CPU, every time they are brought online.

But we want to call fpstate_xstate_init_size() only once. Move it to
fpu__detect(), which only runs once, on the boot CPU.

Also clean up the flow of fpstate_xstate_init_size() a bit, by
removing a 'return' from the middle of the function.

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: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/kernel/fpu/init.c b/arch/x86/kernel/fpu/init.c
index 0b16f61cb2a4e838bae0bd5ffd9f2d3e470f4f61..3e0fee5bc2e7b00fbccc54a21c4114ae9566ee96 100644 (file)
--- a/arch/x86/kernel/fpu/init.c
+++ b/arch/x86/kernel/fpu/init.c
@@ -109,13 +109,12 @@ static void fpstate_xstate_init_size(void)
                setup_clear_cpu_cap(X86_FEATURE_XSAVE);
                setup_clear_cpu_cap(X86_FEATURE_XSAVEOPT);
                xstate_size = sizeof(struct i387_soft_struct);
-               return;
+       } else {
+               if (cpu_has_fxsr)
+                       xstate_size = sizeof(struct i387_fxsave_struct);
+               else
+                       xstate_size = sizeof(struct i387_fsave_struct);
        }
-
-       if (cpu_has_fxsr)
-               xstate_size = sizeof(struct i387_fxsave_struct);
-       else
-               xstate_size = sizeof(struct i387_fsave_struct);
 }
 
 /*
@@ -151,12 +150,6 @@ void fpu__cpu_init(void)
                cr0 |= X86_CR0_EM;
        write_cr0(cr0);
 
-       /*
-        * fpstate_xstate_init_size() is only called once, to avoid overriding
-        * 'xstate_size' during (secondary CPU) bootup or during CPU hotplug.
-        */
-       if (xstate_size == 0)
-               fpstate_xstate_init_size();
 
        mxcsr_feature_mask_init();
        xsave_init();
@@ -194,5 +187,7 @@ void fpu__detect(struct cpuinfo_x86 *c)
        else
                clear_cpu_cap(c, X86_FEATURE_FPU);
 
-       /* The final cr0 value is set in fpu_init() */
+       /* The final cr0 value is set later, in fpu_init() */
+
+       fpstate_xstate_init_size();
 }