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authorPaul Mackerras <paulus@samba.org>2015-03-28 04:21:07 +0100
committerAlexander Graf <agraf@suse.de>2015-04-21 15:21:32 +0200
commitccc07772c99befeda7a7a4b1d05a6f3b762518c2 (patch)
treec6f47a2039a097c82a0917b211c4e4d325a9ea64 /arch
parentKVM: PPC: Book3S HV: Get rid of vcore nap_count and n_woken (diff)
downloadlinux-ccc07772c99befeda7a7a4b1d05a6f3b762518c2.tar.xz
linux-ccc07772c99befeda7a7a4b1d05a6f3b762518c2.zip
KVM: PPC: Book3S HV: Don't wake thread with no vcpu on guest IPI
When running a multi-threaded guest and vcpu 0 in a virtual core is not running in the guest (i.e. it is busy elsewhere in the host), thread 0 of the physical core will switch the MMU to the guest and then go to nap mode in the code at kvm_do_nap. If the guest sends an IPI to thread 0 using the msgsndp instruction, that will wake up thread 0 and cause all the threads in the guest to exit to the host unnecessarily. To avoid the unnecessary exit, this arranges for the PECEDP bit to be cleared in this situation. When napping due to a H_CEDE from the guest, we still set PECEDP so that the thread will wake up on an IPI sent using msgsndp. Signed-off-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Alexander Graf <agraf@suse.de>
Diffstat (limited to 'arch')
-rw-r--r--arch/powerpc/kvm/book3s_hv_rmhandlers.S10
1 files changed, 7 insertions, 3 deletions
diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
index 6716db3f1a2b..12d7e4c8dc54 100644
--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
@@ -191,6 +191,7 @@ kvmppc_primary_no_guest:
li r3, NAPPING_NOVCPU
stb r3, HSTATE_NAPPING(r13)
+ li r3, 0 /* Don't wake on privileged (OS) doorbell */
b kvm_do_nap
kvm_novcpu_wakeup:
@@ -2129,10 +2130,13 @@ _GLOBAL(kvmppc_h_cede) /* r3 = vcpu pointer, r11 = msr, r13 = paca */
bl kvmhv_accumulate_time
#endif
+ lis r3, LPCR_PECEDP@h /* Do wake on privileged doorbell */
+
/*
* Take a nap until a decrementer or external or doobell interrupt
- * occurs, with PECE1, PECE0 and PECEDP set in LPCR. Also clear the
- * runlatch bit before napping.
+ * occurs, with PECE1 and PECE0 set in LPCR.
+ * On POWER8, if we are ceding, also set PECEDP.
+ * Also clear the runlatch bit before napping.
*/
kvm_do_nap:
mfspr r0, SPRN_CTRLF
@@ -2144,7 +2148,7 @@ kvm_do_nap:
mfspr r5,SPRN_LPCR
ori r5,r5,LPCR_PECE0 | LPCR_PECE1
BEGIN_FTR_SECTION
- oris r5,r5,LPCR_PECEDP@h
+ rlwimi r5, r3, 0, LPCR_PECEDP
END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
mtspr SPRN_LPCR,r5
isync