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Mon, 8 Nov 2021 15:12:05 GMT Received: from b03ledav001.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 7F6476E052; Mon, 8 Nov 2021 15:12:05 +0000 (GMT) Received: from b03ledav001.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id A04236E064; Mon, 8 Nov 2021 15:12:04 +0000 (GMT) Received: from [9.160.104.209] (unknown [9.160.104.209]) by b03ledav001.gho.boulder.ibm.com (Postfix) with ESMTP; Mon, 8 Nov 2021 15:12:04 +0000 (GMT) Message-ID: Date: Mon, 8 Nov 2021 10:12:03 -0500 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.1.0 Subject: Re: [PATCH] s390x: kvm: adjust diag318 resets to retain data Content-Language: en-US To: Christian Borntraeger , qemu-s390x@nongnu.org, qemu-devel@nongnu.org References: <20211105224646.803661-1-walling@linux.ibm.com> From: Collin Walling In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: 50Rc8hMJPyvcLY78ZAMU8hjkB1AlKGxK X-Proofpoint-GUID: CCUsFDnA2m0ZJh_CTlOrhWUFLnmCksuE X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.790,Hydra:6.0.425,FMLib:17.0.607.475 definitions=2021-11-08_05,2021-11-08_01,2020-04-07_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 malwarescore=0 impostorscore=0 bulkscore=0 clxscore=1015 mlxscore=0 mlxlogscore=999 spamscore=0 phishscore=0 priorityscore=1501 adultscore=0 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2110150000 definitions=main-2111080093 Received-SPF: pass client-ip=148.163.156.1; envelope-from=walling@linux.ibm.com; helo=mx0a-001b2d01.pphosted.com X-Spam_score_int: -50 X-Spam_score: -5.1 X-Spam_bar: ----- X-Spam_report: (-5.1 / 5.0 requ) BAYES_00=-1.9, CTE_8BIT_MISMATCH=0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-3.06, RCVD_IN_MSPIKE_H2=-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: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: thuth@redhat.com, cohuck@redhat.com, david@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 11/8/21 03:07, Christian Borntraeger wrote: > > > Am 05.11.21 um 23:46 schrieb Collin Walling: >> The CPNC portion of the diag 318 data is erroneously reset during an >> initial CPU reset caused by SIGP. Let's go ahead and relocate the >> diag318_info field within the CPUS390XState struct such that it is >> only zeroed during a clear reset. This way, the CPNC will be retained >> for each VCPU in the configuration after the diag 318 instruction >> has been invoked by the kernel. >> >> Additionally, the diag 318 data reset is handled via the CPU reset >> code. The set_diag318 code can be merged into the handler function >> and the helper functions can consequently be removed. >> >> Signed-off-by: Collin Walling [...] >> diff --git a/target/s390x/kvm/kvm.c b/target/s390x/kvm/kvm.c >> index 5b1fdb55c4..ed9c477b6f 100644 >> --- a/target/s390x/kvm/kvm.c >> +++ b/target/s390x/kvm/kvm.c >> @@ -1576,18 +1576,6 @@ static int handle_sw_breakpoint(S390CPU *cpu, >> struct kvm_run *run) >>       return -ENOENT; >>   } >>   -void kvm_s390_set_diag318(CPUState *cs, uint64_t diag318_info) >> -{ >> -    CPUS390XState *env = &S390_CPU(cs)->env; >> - >> -    /* Feat bit is set only if KVM supports sync for diag318 */ >> -    if (s390_has_feat(S390_FEAT_DIAG_318)) { >> -        env->diag318_info = diag318_info; >> -        cs->kvm_run->s.regs.diag318 = diag318_info; >> -        cs->kvm_run->kvm_dirty_regs |= KVM_SYNC_DIAG318; >> -    } >> -} >> - >>   static void handle_diag_318(S390CPU *cpu, struct kvm_run *run) >>   { >>       uint64_t reg = (run->s390_sieic.ipa & 0x00f0) >> 4; >> @@ -1604,8 +1592,11 @@ static void handle_diag_318(S390CPU *cpu, >> struct kvm_run *run) >>       } >>         CPU_FOREACH(t) { >> -        run_on_cpu(t, s390_do_cpu_set_diag318, >> -                   RUN_ON_CPU_HOST_ULONG(diag318_info)); >> +        CPUS390XState *env = &S390_CPU(t)->env; >> + >> +        env->diag318_info = diag318_info; >> +        t->kvm_run->s.regs.diag318 = diag318_info; >> +        t->kvm_run->kvm_dirty_regs |= KVM_SYNC_DIAG318; > > I am not sure if this part works fine. What happens if > another CPU is currently in SIE (not stopped). > Then this change will be not visible in that CPU and in > fact this change will be overwritten when the CPU exits to QEMU. > Ah, I should've paid more attention to what run_on_cpu does. I now see that it makes CPU changes atomic. I'll reintroduce the helper as a static function and use the run_on_cpu again. -- Regards, Collin Stay safe and stay healthy