1 files changed, 37 insertions, 17 deletions

diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
index edb2ccdbb2ba..65c105b17a25 100644
--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
@@ -201,8 +201,6 @@ kvmppc_primary_no_guest:
         bge     kvm_novcpu_exit /* another thread already exiting */
         li      r3, NAPPING_NOVCPU
         stb     r3, HSTATE_NAPPING(r13)
-        li      r3, 1
-        stb     r3, HSTATE_HWTHREAD_REQ(r13)
 
         b       kvm_do_nap
 
@@ -293,6 +291,8 @@ kvm_start_guest:
         /* if we have no vcpu to run, go back to sleep */
         beq     kvm_no_guest
 
+kvm_secondary_got_guest:
+
         /* Set HSTATE_DSCR(r13) to something sensible */
         ld      r6, PACA_DSCR(r13)
         std     r6, HSTATE_DSCR(r13)
@@ -318,27 +318,46 @@ kvm_start_guest:
         stwcx.  r3, 0, r4
         bne     51b
 
+/*
+ * At this point we have finished executing in the guest.
+ * We need to wait for hwthread_req to become zero, since
+ * we may not turn on the MMU while hwthread_req is non-zero.
+ * While waiting we also need to check if we get given a vcpu to run.
+ */
 kvm_no_guest:
-        li      r0, KVM_HWTHREAD_IN_NAP
+        lbz     r3, HSTATE_HWTHREAD_REQ(r13)
+        cmpwi   r3, 0
+        bne     53f
+        HMT_MEDIUM
+        li      r0, KVM_HWTHREAD_IN_KERNEL
         stb     r0, HSTATE_HWTHREAD_STATE(r13)
-kvm_do_nap:
-        /* Clear the runlatch bit before napping */
-        mfspr   r2, SPRN_CTRLF
-        clrrdi  r2, r2, 1
-        mtspr   SPRN_CTRLT, r2
-
+        /* need to recheck hwthread_req after a barrier, to avoid race */
+        sync
+        lbz     r3, HSTATE_HWTHREAD_REQ(r13)
+        cmpwi   r3, 0
+        bne     54f
+/*
+ * We jump to power7_wakeup_loss, which will return to the caller
+ * of power7_nap in the powernv cpu offline loop.  The value we
+ * put in r3 becomes the return value for power7_nap.
+ */
         li      r3, LPCR_PECE0
         mfspr   r4, SPRN_LPCR
         rlwimi  r4, r3, 0, LPCR_PECE0 | LPCR_PECE1
         mtspr   SPRN_LPCR, r4
-        isync
-        std     r0, HSTATE_SCRATCH0(r13)
-        ptesync
-        ld      r0, HSTATE_SCRATCH0(r13)
-1:      cmpd    r0, r0
-        bne     1b
-        nap
-        b       .
+        li      r3, 0
+        b       power7_wakeup_loss
+
+53:     HMT_LOW
+        ld      r4, HSTATE_KVM_VCPU(r13)
+        cmpdi   r4, 0
+        beq     kvm_no_guest
+        HMT_MEDIUM
+        b       kvm_secondary_got_guest
+
+54:     li      r0, KVM_HWTHREAD_IN_KVM
+        stb     r0, HSTATE_HWTHREAD_STATE(r13)
+        b       kvm_no_guest
 
 /******************************************************************************
  *                                                                            *
@@ -2172,6 +2191,7 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_206)
          * occurs, with PECE1, PECE0 and PECEDP set in LPCR. Also clear the
          * runlatch bit before napping.
          */
+kvm_do_nap:
         mfspr   r2, SPRN_CTRLF
         clrrdi  r2, r2, 1
         mtspr   SPRN_CTRLT, r2