ppc/kvm: Set the runlatch bit of a CPU just before starting guest

The secondary threads in the core are kept offline before launching guests
in kvm on powerpc: "371fefd6f2dc4666:KVM: PPC: Allow book3s_hv guests to use
SMT processor modes."

Hence their runlatch bits are cleared. When the secondary threads are called
in to start a guest, their runlatch bits need to be set to indicate that they
are busy. The primary thread has its runlatch bit set though, but there is no
harm in setting this bit once again. Hence set the runlatch bit for all
threads before they start guest.

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 ffbb871c2bd803827fa5a78658f29d2fa8a1dbd6..b25407533618365a1201f4585b286534ae470f3a 100644 (file)
--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
@@ -242,6 +242,12 @@ kvm_novcpu_exit:
  */
        .globl  kvm_start_guest
 kvm_start_guest:
+
+       /* Set runlatch bit the minute you wake up from nap */
+       mfspr   r1, SPRN_CTRLF
+       ori     r1, r1, 1
+       mtspr   SPRN_CTRLT, r1
+
        ld      r2,PACATOC(r13)
 
        li      r0,KVM_HWTHREAD_IN_KVM