[Qemu-devel] [PATCH 1/2] KVM: PPC: booke: save/restore VRSAVE (a.k.a. USPRG0)

[Scott Wood]

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 <address@hidden>
---
 arch/powerpc/include/asm/kvm_host.h |    1 +
 arch/powerpc/kernel/asm-offsets.c   |    1 +
 arch/powerpc/kvm/booke_interrupts.S |    5 ++++-
 3 files changed, 6 insertions(+), 1 deletions(-)

diff --git a/arch/powerpc/include/asm/kvm_host.h 
b/arch/powerpc/include/asm/kvm_host.h
index bfb0e0f..34b8732 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -228,6 +228,7 @@ struct kvm_vcpu_arch {
        ulong hflags;
        ulong guest_owned_ext;
 #endif
+       u32 vrsave; /* also USPRG0 */
        u32 mmucr;
        ulong shadow_msr;
        ulong sprg4;
diff --git a/arch/powerpc/kernel/asm-offsets.c 
b/arch/powerpc/kernel/asm-offsets.c
index 2b223de..7b9e35e 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -395,6 +395,7 @@ int main(void)
        DEFINE(VCPU_HOST_STACK, offsetof(struct kvm_vcpu, arch.host_stack));
        DEFINE(VCPU_HOST_PID, offsetof(struct kvm_vcpu, arch.host_pid));
        DEFINE(VCPU_GPRS, offsetof(struct kvm_vcpu, arch.gpr));
+       DEFINE(VCPU_VRSAVE, offsetof(struct kvm_vcpu, arch.vrsave));
        DEFINE(VCPU_SPRG4, offsetof(struct kvm_vcpu, arch.sprg4));
        DEFINE(VCPU_SPRG5, offsetof(struct kvm_vcpu, arch.sprg5));
        DEFINE(VCPU_SPRG6, offsetof(struct kvm_vcpu, arch.sprg6));
diff --git a/arch/powerpc/kvm/booke_interrupts.S 
b/arch/powerpc/kvm/booke_interrupts.S
index 54c19d2..cde29c4 100644
--- a/arch/powerpc/kvm/booke_interrupts.S
+++ b/arch/powerpc/kvm/booke_interrupts.S
@@ -184,6 +184,8 @@ _GLOBAL(kvmppc_resume_host)
        stw     r3, VCPU_GPR(r4)(r4)
        mfspr   r3, SPRN_SRR0
        stw     r3, VCPU_PC(r4)
+       mfspr   r3, SPRN_VRSAVE
+       stw     r3, VCPU_VRSAVE(r4)
 
        /* Restore host stack pointer and PID before IVPR, since the host
         * exception handlers use them. */
@@ -395,9 +397,10 @@ 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_VRSAVE(r4)
+       mtspr   SPRN_VRSAVE, r3
        lwz     r3, VCPU_SPRG4(r4)
        mtspr   SPRN_SPRG4W, r3
        lwz     r3, VCPU_SPRG5(r4)
-- 
1.7.1