x86/fpu: Remove failure return from fpstate_alloc_init()

Remove the failure code and propagate this down to callers.

Note that this function still has an 'init' aspect, which must be
called.
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

@@ -44,7 +44,7 @@ extern void fpu__init_system_xstate(void);
 extern void fpu__init_cpu_xstate(void);
 extern void fpu__init_system(struct cpuinfo_x86 *c);
 
-extern int fpstate_alloc_init(struct fpu *fpu);
+extern void fpstate_alloc_init(struct fpu *fpu);
 extern void fpstate_init(struct fpu *fpu);
 extern void fpu__clear(struct task_struct *tsk);
 

arch/x86/kernel/fpu/core.c

@@ -259,26 +259,17 @@ int fpu__copy(struct fpu *dst_fpu, struct fpu *src_fpu)
 }
 
 /*
- * Allocate the backing store for the current task's FPU registers
- * and initialize the registers themselves as well.
- *
- * Can fail.
+ * Initialize the current task's in-memory FPU context:
  */
-int fpstate_alloc_init(struct fpu *fpu)
+void fpstate_alloc_init(struct fpu *fpu)
 {
-	int ret;
-
-	if (WARN_ON_ONCE(fpu != &current->thread.fpu))
-		return -EINVAL;
-	if (WARN_ON_ONCE(fpu->fpstate_active))
-		return -EINVAL;
+	WARN_ON_ONCE(fpu != &current->thread.fpu);
+	WARN_ON_ONCE(fpu->fpstate_active);
 
 	fpstate_init(fpu);
 
 	/* Safe to do for the current task: */
 	fpu->fpstate_active = 1;
-
-	return 0;
 }
 EXPORT_SYMBOL_GPL(fpstate_alloc_init);
 
@@ -340,20 +331,8 @@ void fpu__restore(void)
 	struct task_struct *tsk = current;
 	struct fpu *fpu = &tsk->thread.fpu;
 
-	if (!fpu->fpstate_active) {
-		local_irq_enable();
-		/*
-		 * does a slab alloc which can sleep
-		 */
-		if (fpstate_alloc_init(fpu)) {
-			/*
-			 * ran out of memory!
-			 */
-			do_group_exit(SIGKILL);
-			return;
-		}
-		local_irq_disable();
-	}
+	if (!fpu->fpstate_active)
+		fpstate_alloc_init(fpu);
 
 	/* Avoid __kernel_fpu_begin() right after fpregs_activate() */
 	kernel_fpu_disable();
@@ -379,9 +358,7 @@ void fpu__clear(struct task_struct *tsk)
 		drop_fpu(fpu);
 	} else {
 		if (!fpu->fpstate_active) {
-			/* kthread execs. TODO: cleanup this horror. */
-			if (WARN_ON(fpstate_alloc_init(fpu)))
-				force_sig(SIGKILL, tsk);
+			fpstate_alloc_init(fpu);
 			user_fpu_begin();
 		}
 		restore_init_xstate();

arch/x86/kernel/fpu/xsave.c

@@ -358,8 +358,8 @@ int __restore_xstate_sig(void __user *buf, void __user *buf_fx, int size)
 	if (!access_ok(VERIFY_READ, buf, size))
 		return -EACCES;
 
-	if (!fpu->fpstate_active && fpstate_alloc_init(fpu))
-		return -1;
+	if (!fpu->fpstate_active)
+		fpstate_alloc_init(fpu);
 
 	if (!static_cpu_has(X86_FEATURE_FPU))
 		return fpregs_soft_set(current, NULL,

arch/x86/kvm/x86.c

@@ -6601,8 +6601,8 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 	int r;
 	sigset_t sigsaved;
 
-	if (!fpu->fpstate_active && fpstate_alloc_init(fpu))
-		return -ENOMEM;
+	if (!fpu->fpstate_active)
+		fpstate_alloc_init(fpu);
 
 	if (vcpu->sigset_active)
 		sigprocmask(SIG_SETMASK, &vcpu->sigset, &sigsaved);

arch/x86/math-emu/fpu_entry.c

@@ -149,12 +149,8 @@ void math_emulate(struct math_emu_info *info)
 	struct desc_struct code_descriptor;
 	struct fpu *fpu = &current->thread.fpu;
 
-	if (!fpu->fpstate_active) {
-		if (fpstate_alloc_init(fpu)) {
-			do_group_exit(SIGKILL);
-			return;
-		}
-	}
+	if (!fpu->fpstate_active)
+		fpstate_alloc_init(fpu);
 
 #ifdef RE_ENTRANT_CHECKING
 	if (emulating) {