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Wed, 22 Jul 2020 03:51:37 GMT Received: from b01ledav005.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 5D883AE05F; Wed, 22 Jul 2020 03:51:37 +0000 (GMT) Received: from b01ledav005.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 3891EAE05C; Wed, 22 Jul 2020 03:51:31 +0000 (GMT) Received: from morokweng.localdomain.com (unknown [9.163.58.88]) by b01ledav005.gho.pok.ibm.com (Postfix) with ESMTP; Wed, 22 Jul 2020 03:51:30 +0000 (GMT) From: Thiago Jung Bauermann To: qemu-ppc@nongnu.org Subject: [PATCH v2 3/9] ppc/spapr: Use start-powered-off CPUState property Date: Wed, 22 Jul 2020 00:50:10 -0300 Message-Id: <20200722035016.469075-4-bauerman@linux.ibm.com> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200722035016.469075-1-bauerman@linux.ibm.com> References: <20200722035016.469075-1-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_01:2020-07-21, 2020-07-21 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=1 mlxlogscore=999 malwarescore=0 priorityscore=1501 adultscore=0 mlxscore=0 impostorscore=0 bulkscore=0 phishscore=0 lowpriorityscore=0 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2007220020 Received-SPF: pass client-ip=148.163.158.5; envelope-from=bauerman@linux.ibm.com; helo=mx0b-001b2d01.pphosted.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/07/21 23:52:01 X-ACL-Warn: Detected OS = Linux 3.x [generic] 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: Thiago Jung Bauermann , Peter Maydell , Aleksandar Rikalo , Eduardo Habkost , Aleksandar Markovic , Cornelia Huck , Mark Cave-Ayland , qemu-devel@nongnu.org, qemu-s390x@nongnu.org, qemu-arm@nongnu.org, Artyom Tarasenko , Thomas Huth , Paolo Bonzini , David Hildenbrand , Richard Henderson , Aurelien Jarno , David Gibson 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 | 12 +++++++----- 1 file changed, 7 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..09feeb5f8f 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]; @@ -288,6 +283,13 @@ static PowerPCCPU *spapr_create_vcpu(SpaprCpuCore *sc, int i, Error **errp) cpu->machine_data = g_new0(SpaprCpuState, 1); + /* + * 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. + */ + object_property_set_bool(OBJECT(cs), "start-powered-off", true, + &error_abort); + object_unref(obj); return cpu;