[kvm-devel] fx_init schedule in atomic

[Andrea A. <an...@qu...>]

Hello,

This make sure not to schedule in atomic during fx_init. I also
changed the name of fpu_init to fx_finit to avoid duplicating the name
with fpu_init that is already used in the kernel, this makes grep
simpler if nothing else.

Signed-off-by: Andrea Arcangeli <an...@qu...>

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 578a0c1..5398b1c 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3701,10 +3702,19 @@ void fx_init(struct kvm_vcpu *vcpu)
 {
 	unsigned after_mxcsr_mask;
 
+	/*
+	 * Touch the fpu the first time in non atomic context as if
+	 * this is the first fpu instruction the exception handler
+	 * will fire before the instruction returns and it'll have to
+	 * allocate ram with GFP_KERNEL.
+	 */
+	if (!used_math())
+		fx_save(&vcpu->arch.host_fx_image);
+
 	/* Initialize guest FPU by resetting ours and saving into guest's */
 	preempt_disable();
 	fx_save(&vcpu->arch.host_fx_image);
-	fpu_init();
+	fx_finit();
 	fx_save(&vcpu->arch.guest_fx_image);
 	fx_restore(&vcpu->arch.host_fx_image);
 	preempt_enable();
diff --git a/include/asm-x86/kvm_host.h b/include/asm-x86/kvm_host.h
index 4baa9c9..b9a1421 100644
--- a/include/asm-x86/kvm_host.h
+++ b/include/asm-x86/kvm_host.h
@@ -627,7 +635,7 @@ static inline void fx_restore(struct i387_fxsave_struct *image)
 	asm("fxrstor (%0)":: "r" (image));
 }
 
-static inline void fpu_init(void)
+static inline void fx_finit(void)
 {
 	asm("finit");
 }