KVM: avoid fx_init() schedule in atomic

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 <andrea@qumranet.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index bc224bba1e874caf1625af5bde586b6014b444f3..21338bdb28ff88a2577fb22d79aadfd9fee3cf39 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3703,10 +3703,19 @@ 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 4baa9c9e1f41f5bd65389a828b49e8e0d6905029..1d8cd01fa5147221ccf6e598b8d8f0d3a100bf3e 100644 (file)
--- a/include/asm-x86/kvm_host.h
+++ b/include/asm-x86/kvm_host.h
@@ -627,7 +627,7 @@ 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");
 }