From: Rusty Russell <rusty@rustcorp.com.au>
Date: Mon, 30 Jul 2007 06:29:56 +0000 (+1000)
Subject: KVM: fx_init() needs preemption disabled while it plays with the FPU state
X-Git-Tag: v2.6.24-rc1~1365^2~75
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9bd01506ee551689b90ba5822c28ef55207146af;p=linux-2.6

KVM: fx_init() needs preemption disabled while it plays with the FPU state

Now that kvm generally runs with preemption enabled, we need to protect
the fpu intialization sequence.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Avi Kivity <avi@qumranet.com>
---

diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index 7aeaaba79c..5b42731beb 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -693,10 +693,13 @@ void fx_init(struct kvm_vcpu *vcpu)
 
 	} *fx_image;
 
+	/* Initialize guest FPU by resetting ours and saving into guest's */
+	preempt_disable();
 	fx_save(vcpu->host_fx_image);
 	fpu_init();
 	fx_save(vcpu->guest_fx_image);
 	fx_restore(vcpu->host_fx_image);
+	preempt_enable();
 
 	fx_image = (struct fx_image_s *)vcpu->guest_fx_image;
 	fx_image->mxcsr = 0x1f80;