KVM: PPC: booke: save/restore VRSAVE (a.k.a. USPRG0)

Linux doesn't use USPRG0 (now renamed VRSAVE in the architecture, even
when Altivec isn't involved), but a guest might.

Signed-off-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Alexander Graf <agraf@suse.de>

2 files changed, 13 insertions, 1 deletions

diff --git a/arch/powerpc/kvm/booke_interrupts.S b/arch/powerpc/kvm/booke_interrupts.S
index 1cc471faac2d..b58ccae95904 100644
--- a/arch/powerpc/kvm/booke_interrupts.S
+++ b/arch/powerpc/kvm/booke_interrupts.S
@@ -380,7 +380,6 @@ lightweight_exit:
          * because host interrupt handlers would get confused. */
         lwz     r1, VCPU_GPR(r1)(r4)
 
-        /* XXX handle USPRG0 */
         /* Host interrupt handlers may have clobbered these guest-readable
          * SPRGs, so we need to reload them here with the guest's values. */
         lwz     r3, VCPU_SPRG4(r4)
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index ec3d2e75c0a8..9e6aa8bfd160 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -298,12 +298,25 @@ void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu)
 
 void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 {
+#ifdef CONFIG_BOOKE
+        /*
+         * vrsave (formerly usprg0) isn't used by Linux, but may
+         * be used by the guest.
+         *
+         * On non-booke this is associated with Altivec and
+         * is handled by code in book3s.c.
+         */
+        mtspr(SPRN_VRSAVE, vcpu->arch.vrsave);
+#endif
         kvmppc_core_vcpu_load(vcpu, cpu);
 }
 
 void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
 {
         kvmppc_core_vcpu_put(vcpu);
+#ifdef CONFIG_BOOKE
+        vcpu->arch.vrsave = mfspr(SPRN_VRSAVE);
+#endif
 }
 
 int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,