KVM: PPC: Use PACA backed shadow vcpu

We're being horribly racy right now. All the entry and exit code hijacks
random fields from the PACA that could easily be used by different code in
case we get interrupted, for example by a #MC or even page fault.

After discussing this with Ben, we figured it's best to reserve some more
space in the PACA and just shove off some vcpu state to there.

That way we can drastically improve the readability of the code, make it
less racy and less complex.

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

1 files changed, 8 insertions, 24 deletions

diff --git a/arch/powerpc/kvm/book3s_64_rmhandlers.S b/arch/powerpc/kvm/book3s_64_rmhandlers.S
index fb7dd2e9ac88..cd9f0b609e48 100644
--- a/arch/powerpc/kvm/book3s_64_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_64_rmhandlers.S
@@ -45,37 +45,21 @@ kvmppc_trampoline_\intno:
          * To distinguish, we check a magic byte in the PACA
          */
         mfspr   r13, SPRN_SPRG_PACA             /* r13 = PACA */
-        std     r12, (PACA_EXMC + EX_R12)(r13)
+        std     r12, PACA_KVM_SCRATCH0(r13)
         mfcr    r12
-        stw     r12, (PACA_EXMC + EX_CCR)(r13)
+        stw     r12, PACA_KVM_SCRATCH1(r13)
         lbz     r12, PACA_KVM_IN_GUEST(r13)
         cmpwi   r12, 0
         bne     ..kvmppc_handler_hasmagic_\intno
         /* No KVM guest? Then jump back to the Linux handler! */
-        lwz     r12, (PACA_EXMC + EX_CCR)(r13)
+        lwz     r12, PACA_KVM_SCRATCH1(r13)
         mtcr    r12
-        ld      r12, (PACA_EXMC + EX_R12)(r13)
+        ld      r12, PACA_KVM_SCRATCH0(r13)
         mfspr   r13, SPRN_SPRG_SCRATCH0         /* r13 = original r13 */
         b       kvmppc_resume_\intno            /* Get back original handler */
 
         /* Now we know we're handling a KVM guest */
 ..kvmppc_handler_hasmagic_\intno:
-        /* Unset guest state */
-        li      r12, 0
-        stb     r12, PACA_KVM_IN_GUEST(r13)
-
-        std     r1, (PACA_EXMC+EX_R9)(r13)
-        std     r10, (PACA_EXMC+EX_R10)(r13)
-        std     r11, (PACA_EXMC+EX_R11)(r13)
-        std     r2, (PACA_EXMC+EX_R13)(r13)
-
-        mfsrr0  r10
-        mfsrr1  r11
-
-        /* Restore R1/R2 so we can handle faults */
-        ld      r1, PACAR1(r13)
-        ld      r2, (PACA_EXMC+EX_SRR0)(r13)
-
         /* Let's store which interrupt we're handling */
         li      r12, \intno
 
@@ -106,16 +90,16 @@ INTERRUPT_TRAMPOLINE	BOOK3S_INTERRUPT_VSX
  *
  * Input Registers:
  *
- * R6 = SRR0
- * R7 = SRR1
+ * R5 = SRR0
+ * R6 = SRR1
  * LR = real-mode IP
  *
  */
 .global kvmppc_handler_lowmem_trampoline
 kvmppc_handler_lowmem_trampoline:
 
-        mtsrr0  r6
-        mtsrr1  r7
+        mtsrr0  r5
+        mtsrr1  r6
         blr
 kvmppc_handler_lowmem_trampoline_end: