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Tue, 22 Sep 2020 11:15:16 -0400 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-236-TNCohAoeOT66zjxvPe1GZQ-1; Tue, 22 Sep 2020 11:15:01 -0400 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 249311017DC9; Tue, 22 Sep 2020 15:15:00 +0000 (UTC) Received: from localhost (unknown [10.10.67.5]) by smtp.corp.redhat.com (Postfix) with ESMTP id 930A673670; Tue, 22 Sep 2020 15:14:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1600787710; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=hQSjgqVtilkBiWKNUMIsXVhf0Cxsgw+4bjov72hIPUQ=; b=cn3i91cvD4pHiQYZRpYq9dHVrMmz3Z3mv12lbYXFuUNacoZ3WKDwzmI6lFiIksavrdqnm4 HgYKpAwsabibphLvKMC0Clb9LBUeaE84EPzHbpjZb+riEvG+XQmH/JbSyHneW5vOxET1Ac shd7hUU/tFmGG5TEnakcYvwdXwKqjoM= X-MC-Unique: TNCohAoeOT66zjxvPe1GZQ-1 From: Eduardo Habkost To: qemu-devel@nongnu.org Subject: [PATCH] i386: Don't try to set MSR_KVM_ASYNC_PF_EN if kernel-irqchip=off Date: Tue, 22 Sep 2020 11:14:55 -0400 Message-Id: <20200922151455.1763896-1-ehabkost@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=63.128.21.124; envelope-from=ehabkost@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/09/22 02:07:04 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -35 X-Spam_score: -3.6 X-Spam_bar: --- X-Spam_report: (-3.6 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.455, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Laurent Vivier , 1896263@bugs.launchpad.net, Eduardo Habkost , kvm@vger.kernel.org, Marcelo Tosatti , "Dr. David Alan Gilbert" , Stefan Hajnoczi , Paolo Bonzini , Vitaly Kuznetsov , Richard Henderson Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) Content-Type: text/plain; charset="utf-8" This addresses the following crash when running Linux v5.8 with kernel-irqchip=3Doff: qemu-system-x86_64: error: failed to set MSR 0x4b564d02 to 0x0 qemu-system-x86_64: ../target/i386/kvm.c:2714: kvm_buf_set_msrs: Assertio= n `ret =3D=3D cpu->kvm_msr_buf->nmsrs' failed. There is a kernel-side fix for the issue too (kernel commit d831de177217 "KVM: x86: always allow writing '0' to MSR_KVM_ASYNC_PF_EN"), but it's nice to simply not trigger the bug if running an older kernel. Fixes: https://bugs.launchpad.net/bugs/1896263 Signed-off-by: Eduardo Habkost --- target/i386/kvm.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/target/i386/kvm.c b/target/i386/kvm.c index 9efb07e7c83..1492f41349f 100644 --- a/target/i386/kvm.c +++ b/target/i386/kvm.c @@ -2818,7 +2818,12 @@ static int kvm_put_msrs(X86CPU *cpu, int level) kvm_msr_entry_add(cpu, MSR_IA32_TSC, env->tsc); kvm_msr_entry_add(cpu, MSR_KVM_SYSTEM_TIME, env->system_time_msr); kvm_msr_entry_add(cpu, MSR_KVM_WALL_CLOCK, env->wall_clock_msr); - if (env->features[FEAT_KVM] & (1 << KVM_FEATURE_ASYNC_PF)) { + /* + * Some kernel versions (v5.8) won't let MSR_KVM_ASYNC_PF_EN to be= set + * at all if kernel-irqchip=3Doff, so don't try to set it in that = case. + */ + if (env->features[FEAT_KVM] & (1 << KVM_FEATURE_ASYNC_PF) && + kvm_irqchip_in_kernel()) { kvm_msr_entry_add(cpu, MSR_KVM_ASYNC_PF_EN, env->async_pf_en_m= sr); } if (env->features[FEAT_KVM] & (1 << KVM_FEATURE_PV_EOI)) { --=20 2.26.2