From patchwork Tue Apr 21 17:35:14 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Graf X-Patchwork-Id: 463424 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id F3FF6140218 for ; Wed, 22 Apr 2015 03:35:58 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933520AbbDURfo (ORCPT ); Tue, 21 Apr 2015 13:35:44 -0400 Received: from cantor2.suse.de ([195.135.220.15]:38288 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755741AbbDURf0 (ORCPT ); Tue, 21 Apr 2015 13:35:26 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (charybdis-ext.suse.de [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 1EFC2AD6D; Tue, 21 Apr 2015 17:35:21 +0000 (UTC) From: Alexander Graf To: kvm-ppc@vger.kernel.org Cc: kvm@vger.kernel.org, pbonzini@redhat.com, Paul Mackerras Subject: [PULL 16/21] KVM: PPC: Book3S HV: Don't wake thread with no vcpu on guest IPI Date: Tue, 21 Apr 2015 19:35:14 +0200 Message-Id: <1429637719-172312-17-git-send-email-agraf@suse.de> X-Mailer: git-send-email 1.7.12.4 In-Reply-To: <1429637719-172312-1-git-send-email-agraf@suse.de> References: <1429637719-172312-1-git-send-email-agraf@suse.de> Sender: kvm-ppc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm-ppc@vger.kernel.org From: Paul Mackerras 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 Signed-off-by: Alexander Graf --- arch/powerpc/kvm/book3s_hv_rmhandlers.S | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S index 6716db3..12d7e4c 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