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Thu, 23 Jul 2020 02:57:44 GMT Received: from b01ledav006.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 95DC5AC059; Thu, 23 Jul 2020 02:57:44 +0000 (GMT) Received: from b01ledav006.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id D5687AC062; Thu, 23 Jul 2020 02:57:37 +0000 (GMT) Received: from morokweng.localdomain.com (unknown [9.211.93.190]) by b01ledav006.gho.pok.ibm.com (Postfix) with ESMTP; Thu, 23 Jul 2020 02:57:37 +0000 (GMT) From: Thiago Jung Bauermann To: qemu-ppc@nongnu.org Subject: [PATCH v3 3/8] ppc/spapr: Use start-powered-off CPUState property Date: Wed, 22 Jul 2020 23:56:52 -0300 Message-Id: <20200723025657.644724-4-bauerman@linux.ibm.com> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200723025657.644724-1-bauerman@linux.ibm.com> References: <20200723025657.644724-1-bauerman@linux.ibm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.235, 18.0.687 definitions=2020-07-22_17:2020-07-22, 2020-07-22 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 impostorscore=0 mlxscore=0 phishscore=0 priorityscore=1501 clxscore=1015 lowpriorityscore=0 adultscore=0 bulkscore=0 suspectscore=1 spamscore=0 mlxlogscore=999 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2007230014 Received-SPF: pass client-ip=148.163.156.1; envelope-from=bauerman@linux.ibm.com; helo=mx0a-001b2d01.pphosted.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/07/22 22:57:53 X-ACL-Warn: Detected OS = Linux 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, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-1, 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: Peter Maydell , David Hildenbrand , Mark Cave-Ayland , qemu-devel@nongnu.org, Aleksandar Markovic , Thomas Huth , David Gibson , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , Artyom Tarasenko , Aleksandar Rikalo , Eduardo Habkost , Greg Kurz , qemu-s390x@nongnu.org, qemu-arm@nongnu.org, =?UTF-8?q?Alex=20Benn=C3=A9e?= , Richard Henderson , Cornelia Huck , Aurelien Jarno , Paolo Bonzini , Thiago Jung Bauermann Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" PowerPC sPAPR CPUs start in the halted state, and spapr_reset_vcpu() attempts to implement this by setting CPUState::halted to 1. But that's too late for the case of hotplugged CPUs in a machine configure with 2 or more threads per core. By then, other parts of QEMU have already caused the vCPU to run in an unitialized state a couple of times. For example, ppc_cpu_reset() calls ppc_tlb_invalidate_all(), which ends up calling async_run_on_cpu(). This kicks the new vCPU while it has CPUState::halted = 0, causing QEMU to issue a KVM_RUN ioctl on the new vCPU before the guest is able to make the start-cpu RTAS call to initialize its register state. This problem doesn't seem to cause visible issues for regular guests, but on a secure guest running under the Ultravisor it does. The Ultravisor relies on being able to snoop on the start-cpu RTAS call to map vCPUs to guests, and this issue causes it to see a stray vCPU that doesn't belong to any guest. Fix by setting the start-powered-off CPUState property in spapr_create_vcpu(), which makes cpu_common_reset() initialize CPUState::halted to 1 at an earlier moment. Suggested-by: Eduardo Habkost Signed-off-by: Thiago Jung Bauermann --- hw/ppc/spapr_cpu_core.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) NB: Tested on ppc64le pseries KVM guest with two threads per core. Hot-plugging additional cores doesn't cause the bug described above anymore. diff --git a/hw/ppc/spapr_cpu_core.c b/hw/ppc/spapr_cpu_core.c index c4f47dcc04..2125fdac34 100644 --- a/hw/ppc/spapr_cpu_core.c +++ b/hw/ppc/spapr_cpu_core.c @@ -36,11 +36,6 @@ static void spapr_reset_vcpu(PowerPCCPU *cpu) cpu_reset(cs); - /* All CPUs start halted. CPU0 is unhalted from the machine level - * reset code and the rest are explicitly started up by the guest - * using an RTAS call */ - cs->halted = 1; - env->spr[SPR_HIOR] = 0; lpcr = env->spr[SPR_LPCR]; @@ -274,6 +269,11 @@ static PowerPCCPU *spapr_create_vcpu(SpaprCpuCore *sc, int i, Error **errp) cs = CPU(obj); cpu = POWERPC_CPU(obj); + /* + * All CPUs start halted. CPU0 is unhalted from the machine level reset code + * and the rest are explicitly started up by the guest using an RTAS call. + */ + cs->start_powered_off = true; cs->cpu_index = cc->core_id + i; spapr_set_vcpu_id(cpu, cs->cpu_index, &local_err); if (local_err) {