[PATCH 030/104] KVM: fx_init() needs preemption disabled while it plays with the FPU state

Avi Kivity
2007-09-17T08:31:12Z

From: Rusty Russell <rusty-8n+1lVoiYb80n/F98K4Iww@public.gmane.org>

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

Signed-off-by: Rusty Russell <rusty-8n+1lVoiYb80n/F98K4Iww@public.gmane.org>
Signed-off-by: Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
---
drivers/kvm/kvm_main.c | 3 +++
1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index 7aeaaba..5b42731 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;