KVM: PPC: e500mc: Move r1/r2 restoration very early

If we hit any exception whatsoever in the restore path and r1/r2 aren't the
host registers, we don't get a working oops. So it's always a good idea to
restore them as early as possible.

This time, it actually has practical reasons to do so too, since we need to
have the host page fault handler fix up our guest instruction read code. And
for that to work we need r1/r2 restored.

Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>

diff --git a/arch/powerpc/kvm/bookehv_interrupts.S b/arch/powerpc/kvm/bookehv_interrupts.S
index 9eaeebd86e449fc582798f92e4ce5304739ce614..63023ae14da4d6c0f80ff7dadc5e5ad1a79fbfcd 100644 (file)
--- a/arch/powerpc/kvm/bookehv_interrupts.S
+++ b/arch/powerpc/kvm/bookehv_interrupts.S
@@ -67,6 +67,12 @@
  * saved in vcpu: cr, ctr, r3-r13
  */
 .macro kvm_handler_common intno, srr0, flags
+       /* Restore host stack pointer */
+       PPC_STL r1, VCPU_GPR(r1)(r4)
+       PPC_STL r2, VCPU_GPR(r2)(r4)
+       PPC_LL  r1, VCPU_HOST_STACK(r4)
+       PPC_LL  r2, HOST_R2(r1)
+
        mfspr   r10, SPRN_PID
        lwz     r8, VCPU_HOST_PID(r4)
        PPC_LL  r11, VCPU_SHARED(r4)
@@ -290,10 +296,8 @@ _GLOBAL(kvmppc_resume_host)
        /* Save remaining volatile guest register state to vcpu. */
        mfspr   r3, SPRN_VRSAVE
        PPC_STL r0, VCPU_GPR(r0)(r4)
-       PPC_STL r1, VCPU_GPR(r1)(r4)
        mflr    r5
        mfspr   r6, SPRN_SPRG4
-       PPC_STL r2, VCPU_GPR(r2)(r4)
        PPC_STL r5, VCPU_LR(r4)
        mfspr   r7, SPRN_SPRG5
        PPC_STL r3, VCPU_VRSAVE(r4)
@@ -334,10 +338,6 @@ _GLOBAL(kvmppc_resume_host)
        mtspr   SPRN_EPCR, r3
        isync
 
-       /* Restore host stack pointer */
-       PPC_LL  r1, VCPU_HOST_STACK(r4)
-       PPC_LL  r2, HOST_R2(r1)
-
        /* Switch to kernel stack and jump to handler. */
        PPC_LL  r3, HOST_RUN(r1)
        mr      r5, r14 /* intno */