x86/fpu: Rename fpu_alloc() to fpstate_alloc()

Use the fpu__*() namespace for fpstate_alloc() as well.

Also add a comment about FPU state alignment.
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>

arch/x86/include/asm/fpu-internal.h

@@ -569,7 +569,7 @@ static inline unsigned short get_fpu_mxcsr(struct task_struct *tsk)
 	}
 }
 
-extern int fpu_alloc(struct fpu *fpu);
+extern int fpstate_alloc(struct fpu *fpu);
 
 static inline void fpu_free(struct fpu *fpu)
 {

arch/x86/kernel/i387.c

@@ -246,17 +246,21 @@ void fpu_finit(struct fpu *fpu)
 }
 EXPORT_SYMBOL_GPL(fpu_finit);
 
-int fpu_alloc(struct fpu *fpu)
+int fpstate_alloc(struct fpu *fpu)
 {
 	if (fpu->state)
 		return 0;
+
 	fpu->state = kmem_cache_alloc(task_xstate_cachep, GFP_KERNEL);
 	if (!fpu->state)
 		return -ENOMEM;
+
+	/* The CPU requires the FPU state to be aligned to 16 byte boundaries: */
 	WARN_ON((unsigned long)fpu->state & 15);
+
 	return 0;
 }
-EXPORT_SYMBOL_GPL(fpu_alloc);
+EXPORT_SYMBOL_GPL(fpstate_alloc);
 
 /*
  * Allocate the backing store for the current task's FPU registers
@@ -276,7 +280,7 @@ int fpstate_alloc_init(struct task_struct *curr)
 	/*
 	 * Memory allocation at the first usage of the FPU and other state.
 	 */
-	ret = fpu_alloc(&curr->thread.fpu);
+	ret = fpstate_alloc(&curr->thread.fpu);
 	if (ret)
 		return ret;
 
@@ -310,7 +314,7 @@ static int fpu__unlazy_stopped(struct task_struct *child)
 	/*
 	 * Memory allocation at the first usage of the FPU and other state.
 	 */
-	ret = fpu_alloc(&child->thread.fpu);
+	ret = fpstate_alloc(&child->thread.fpu);
 	if (ret)
 		return ret;
 

arch/x86/kernel/process.c

@@ -92,7 +92,7 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
 	dst->thread.fpu.state = NULL;
 	task_disable_lazy_fpu_restore(dst);
 	if (tsk_used_math(src)) {
-		int err = fpu_alloc(&dst->thread.fpu);
+		int err = fpstate_alloc(&dst->thread.fpu);
 		if (err)
 			return err;
 		fpu_copy(dst, src);

arch/x86/kvm/x86.c

@@ -7007,7 +7007,7 @@ int fx_init(struct kvm_vcpu *vcpu)
 {
 	int err;
 
-	err = fpu_alloc(&vcpu->arch.guest_fpu);
+	err = fpstate_alloc(&vcpu->arch.guest_fpu);
 	if (err)
 		return err;