From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ozlabs.org (ozlabs.org [IPv6:2401:3900:2:1::2]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 2D8C51A1834 for ; Thu, 14 Jan 2016 14:16:26 +1100 (AEDT) Received: from e23smtp06.au.ibm.com (e23smtp06.au.ibm.com [202.81.31.148]) (using TLSv1 with cipher CAMELLIA256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id EADD014031E for ; Thu, 14 Jan 2016 14:16:25 +1100 (AEDT) Received: from localhost by e23smtp06.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 14 Jan 2016 13:16:24 +1000 Received: from d23relay06.au.ibm.com (d23relay06.au.ibm.com [9.185.63.219]) by d23dlp01.au.ibm.com (Postfix) with ESMTP id C28082CE8054 for ; Thu, 14 Jan 2016 14:16:19 +1100 (EST) Received: from d23av01.au.ibm.com (d23av01.au.ibm.com [9.190.234.96]) by d23relay06.au.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id u0E3G1d722478926 for ; Thu, 14 Jan 2016 14:16:10 +1100 Received: from d23av01.au.ibm.com (localhost [127.0.0.1]) by d23av01.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id u0E3FkR8018606 for ; Thu, 14 Jan 2016 14:15:47 +1100 Subject: [PATCH 3/3] KVM: PPC: Book3S HV: Fix soft lockups in KVM on HMI for time base errors From: Mahesh J Salgaonkar To: linuxppc-dev , Paul Mackerras , Michael Ellerman Cc: KVM-PPC , KVM Date: Thu, 14 Jan 2016 08:45:28 +0530 Message-ID: <20160114031528.1287.7326.stgit@mars> In-Reply-To: <20160114031457.1287.32132.stgit@mars> References: <20160114031457.1287.32132.stgit@mars> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Mahesh Salgaonkar When secondaries are napping in kvm_unsplit_nap() with hwthread_req = 1, the HMI goes ignored even though subcores are already exited the guest. Hence HMI keeps waking up secondaries from nap in a loop and secondaries always go back to nap since no vcore is assigned to them. This makes impossible for primary thread to get hold of secondary threads resulting into a soft lockup in KVM path. This patch fixes this by adding a HMI check just before the thread goes to unsplit nap. Signed-off-by: Mahesh Salgaonkar --- arch/powerpc/kvm/book3s_hv_rmhandlers.S | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S index e8a456e..c5d43b9 100644 --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S @@ -440,6 +440,12 @@ kvm_no_guest: * whole-core mode, so we need to nap. */ kvm_unsplit_nap: + /* Before we head down to nap, check if HMI is pending and handle it */ + cmpwi r12, BOOK3S_INTERRUPT_HMI + bne 55f + li r3, 0 /* NULL argument */ + bl hmi_exception_realmode +55: /* * Ensure that secondary doesn't nap when it has * its vcore pointer set.