From nobody Thu May 2 22:34:39 2024 Delivered-To: importer@patchew.org Received-SPF: temperror (zoho.com: Error in retrieving data from DNS) client-ip=208.118.235.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=temperror (zoho.com: Error in retrieving data from DNS) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org Return-Path: Received: from lists.gnu.org (208.118.235.17 [208.118.235.17]) by mx.zohomail.com with SMTPS id 1512426455370460.9014934404854; Mon, 4 Dec 2017 14:27:35 -0800 (PST) Received: from localhost ([::1]:45533 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eLzCe-00045u-Ed for importer@patchew.org; Mon, 04 Dec 2017 17:27:08 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:39473) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eLzBp-0003jn-7F for qemu-devel@nongnu.org; Mon, 04 Dec 2017 17:26:18 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eLzBo-0005De-5F for qemu-devel@nongnu.org; Mon, 04 Dec 2017 17:26:17 -0500 Received: from 5751f4a1.skybroadband.com ([87.81.244.161]:60537 helo=dan.rpsys.net) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1eLzBj-0005A6-Af; Mon, 04 Dec 2017 17:26:11 -0500 Received: from hex ([192.168.3.34]) (authenticated bits=0) by dan.rpsys.net (8.15.2/8.15.2/Debian-3) with ESMTPSA id vB4MPkEo011755 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT); Mon, 4 Dec 2017 22:25:50 GMT Received: from richard by hex with local (Exim 4.86_2) (envelope-from ) id 1eLzBK-0004wC-NP; Mon, 04 Dec 2017 22:25:46 +0000 From: Richard Purdie To: qemu-devel@nongnu.org, david@gibson.dropbear.id.au Date: Mon, 4 Dec 2017 22:25:43 +0000 Message-Id: <1512426343-18938-1-git-send-email-richard.purdie@linuxfoundation.org> X-Mailer: git-send-email 2.7.4 X-Virus-Scanned: clamav-milter 0.99.2 at dan X-Virus-Status: Clean X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 87.81.244.161 Subject: [Qemu-devel] [PATCH v3] target/ppc: Fix system lockups caused by interrupt_request state corruption X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Richard Purdie , qemu-ppc@nongnu.org Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail: RSF_6 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Occasionally in Linux guests on x86_64 we're seeing logs like: ppc_set_irq: 0x55b4e0d562f0 n_IRQ 8 level 1 =3D> pending 00000100req 000000= 04 when they should read: ppc_set_irq: 0x55b4e0d562f0 n_IRQ 8 level 1 =3D> pending 00000100req 000000= 02 The "00000004" is CPU_INTERRUPT_EXITTB yet the code calls cpu_interrupt(cs, CPU_INTERRUPT_HARD) ("00000002") in this function just before the log message. Something is causing the HARD bit setting to get lost. The knock on effect of losing that bit is the decrementer timer interrupts don't get delivered which causes the guest to sit idle in its idle handler and 'hang'. The issue occurs due to races from code which sets CPU_INTERRUPT_EXITTB. Rather than poking directly into cs->interrupt_request, that code needs to: a) hold BQL b) use the cpu_interrupt() helper This patch fixes the call sites to do this, fixing the hang. The calls are made from a variety of contexts so a helper function is added to handle the necessary locking. This can likely be improved and optimised in the fut= ure but it ensures the code is correct and doesn't lockup as it stands today. Signed-off-by: Richard Purdie --- target/ppc/excp_helper.c | 7 +++---- target/ppc/helper_regs.h | 17 +++++++++++++++-- 2 files changed, 18 insertions(+), 6 deletions(-) v3: Fix make check failures v2: Fixes a compile issue with master and ensures BQL is held in one case where it potentially wasn't. diff --git a/target/ppc/excp_helper.c b/target/ppc/excp_helper.c index e6009e70e5..37d2410726 100644 --- a/target/ppc/excp_helper.c +++ b/target/ppc/excp_helper.c @@ -207,7 +207,7 @@ static inline void powerpc_excp(PowerPCCPU *cpu, int ex= cp_model, int excp) "Entering checkstop state\n"); } cs->halted =3D 1; - cs->interrupt_request |=3D CPU_INTERRUPT_EXITTB; + cpu_interrupt_exittb(cs); } if (env->msr_mask & MSR_HVB) { /* ISA specifies HV, but can be delivered to guest with HV cle= ar @@ -940,7 +940,7 @@ void helper_store_msr(CPUPPCState *env, target_ulong va= l) =20 if (excp !=3D 0) { CPUState *cs =3D CPU(ppc_env_get_cpu(env)); - cs->interrupt_request |=3D CPU_INTERRUPT_EXITTB; + cpu_interrupt_exittb(cs); raise_exception(env, excp); } } @@ -995,8 +995,7 @@ static inline void do_rfi(CPUPPCState *env, target_ulon= g nip, target_ulong msr) /* No need to raise an exception here, * as rfi is always the last insn of a TB */ - cs->interrupt_request |=3D CPU_INTERRUPT_EXITTB; - + cpu_interrupt_exittb(cs); /* Reset the reservation */ env->reserve_addr =3D -1; =20 diff --git a/target/ppc/helper_regs.h b/target/ppc/helper_regs.h index 2627a70176..84fd30c2db 100644 --- a/target/ppc/helper_regs.h +++ b/target/ppc/helper_regs.h @@ -20,6 +20,8 @@ #ifndef HELPER_REGS_H #define HELPER_REGS_H =20 +#include "qemu/main-loop.h" + /* Swap temporary saved registers with GPRs */ static inline void hreg_swap_gpr_tgpr(CPUPPCState *env) { @@ -96,6 +98,17 @@ static inline void hreg_compute_hflags(CPUPPCState *env) env->hflags |=3D env->hflags_nmsr; } =20 +static inline void cpu_interrupt_exittb(CPUState *cs) +{ + if (!qemu_mutex_iothread_locked()) { + qemu_mutex_lock_iothread(); + cpu_interrupt(cs, CPU_INTERRUPT_EXITTB); + qemu_mutex_unlock_iothread(); + } else { + cpu_interrupt(cs, CPU_INTERRUPT_EXITTB); + } +} + static inline int hreg_store_msr(CPUPPCState *env, target_ulong value, int alter_hv) { @@ -114,11 +127,11 @@ static inline int hreg_store_msr(CPUPPCState *env, ta= rget_ulong value, } if (((value >> MSR_IR) & 1) !=3D msr_ir || ((value >> MSR_DR) & 1) !=3D msr_dr) { - cs->interrupt_request |=3D CPU_INTERRUPT_EXITTB; + cpu_interrupt_exittb(cs); } if ((env->mmu_model & POWERPC_MMU_BOOKE) && ((value >> MSR_GS) & 1) !=3D msr_gs) { - cs->interrupt_request |=3D CPU_INTERRUPT_EXITTB; + cpu_interrupt_exittb(cs); } if (unlikely((env->flags & POWERPC_FLAG_TGPR) && ((value ^ env->msr) & (1 << MSR_TGPR)))) { --=20 2.14.1