KVM: PPC: Get rid of unnecessary RFI

Using an RFI in IR=1 is dangerous. We need to set two SRRs and then do an RFI
without getting interrupted at all, because every interrupt could potentially
overwrite the SRR values.

Fortunately, we don't need to RFI in at least this particular case of the code,
so we can just replace it with an mtmsr and b.

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

diff --git a/arch/powerpc/kvm/book3s_64_interrupts.S b/arch/powerpc/kvm/book3s_64_interrupts.S
index 66e3b1179b32512f76a1fdcd0927df3ee05e3919..3c0ba5513077f4906c6965db4b878099a3a02dac 100644 (file)
--- a/arch/powerpc/kvm/book3s_64_interrupts.S
+++ b/arch/powerpc/kvm/book3s_64_interrupts.S
@@ -221,15 +221,8 @@ no_dcbz32_off:
        mflr    r5
        std     r5, VCPU_LR(r7)
 
-       /* XXX convert to safe function call */
-
        /* Restore host msr -> SRR1 */
        ld      r6, VCPU_HOST_MSR(r7)
-       mtsrr1  r6
-
-       /* Restore host IP -> SRR0 */
-       ld      r5, VCPU_HOST_RETIP(r7)
-       mtsrr0  r5
 
        /*
         * For some interrupts, we need to call the real Linux
@@ -246,8 +239,9 @@ no_dcbz32_off:
        cmpwi   r12, BOOK3S_INTERRUPT_DECREMENTER
        beq     call_linux_handler
 
-       /* Back to Interruptable Mode! (goto kvm_return_point) */
-       RFI
+       /* Back to EE=1 */
+       mtmsr   r6
+       b       kvm_return_point
 
 call_linux_handler:
 
@@ -260,10 +254,16 @@ call_linux_handler:
         * interrupt handler!
         *
         * R3 still contains the exit code,
-        * R6 VCPU_HOST_RETIP and
-        * R7 VCPU_HOST_MSR
+        * R5 VCPU_HOST_RETIP and
+        * R6 VCPU_HOST_MSR
         */
 
+       /* Restore host IP -> SRR0 */
+       ld      r5, VCPU_HOST_RETIP(r7)
+
+       /* XXX Better move to a safe function?
+        *     What if we get an HTAB flush in between mtsrr0 and mtsrr1? */
+
        mtlr    r12
 
        ld      r4, VCPU_TRAMPOLINE_LOWMEM(r7)