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>

diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
index b25407533618365a1201f4585b286534ae470f3a..b031f932c0cc3dcc0c452c88f8ba2c3c88cf641d 100644 (file)
--- 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