ppc/kvm: Clear the runlatch bit of a vcpu before napping

When the guest cedes the vcpu or the vcpu has no guest to
run it naps. Clear the runlatch bit of the vcpu before
napping to indicate an idle cpu.

Signed-off-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Acked-by: Paul Mackerras <paulus@samba.org>
Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 11 insertions, 1 deletions

diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
index b25407533618..b031f932c0cc 100644
--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
@@ -315,6 +315,11 @@ kvm_no_guest:
         li      r0, KVM_HWTHREAD_IN_NAP
         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
+
         li      r3, LPCR_PECE0
         mfspr   r4, SPRN_LPCR
         rlwimi  r4, r3, 0, LPCR_PECE0 | LPCR_PECE1
@@ -2005,8 +2010,13 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_206)
 
         /*
          * Take a nap until a decrementer or external or doobell interrupt
-         * occurs, with PECE1, PECE0 and PECEDP set in LPCR
+         * occurs, with PECE1, PECE0 and PECEDP set in LPCR. Also clear the
+         * runlatch bit before napping.
          */
+        mfspr   r2, SPRN_CTRLF
+        clrrdi  r2, r2, 1
+        mtspr   SPRN_CTRLT, r2
+
         li      r0,1
         stb     r0,HSTATE_HWTHREAD_REQ(r13)
         mfspr   r5,SPRN_LPCR