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Thu, 15 May 2025 15:21:56 +0000 (GMT) Message-ID: <2b0df92c-6f5b-4dcb-a1ef-bc9c169fa0d0@linux.ibm.com> Date: Thu, 15 May 2025 10:21:55 -0500 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 31/50] ppc/xive: Fix high prio group interrupt being preempted by low prio VP To: Nicholas Piggin , qemu-ppc@nongnu.org Cc: qemu-devel@nongnu.org, =?UTF-8?B?RnLDqWTDqXJpYyBCYXJyYXQ=?= , Glenn Miles , Caleb Schlossin References: <20250512031100.439842-1-npiggin@gmail.com> <20250512031100.439842-32-npiggin@gmail.com> Content-Language: en-US From: Mike Kowal In-Reply-To: <20250512031100.439842-32-npiggin@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: owtLgYWb4y_JCBvXXLj5NbDVryaDycND X-Authority-Analysis: v=2.4 cv=XK4wSRhE c=1 sm=1 tr=0 ts=68260697 cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=IkcTkHD0fZMA:10 a=dt9VzEwgFbYA:10 a=VnNF1IyMAAAA:8 a=pGLkceISAAAA:8 a=k6hdcXhxsaq_Xb-7T0YA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 X-Proofpoint-GUID: 5M-Ee_X9Wb0CHg_4kQCAeM6AyFoLMuUS X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwNTE1MDE1MCBTYWx0ZWRfX+Jty97Ln0mQj YRUDAg9k5Mmo3hvoy9ETOoam8FYIXuLo1azwSM3wFlQkjL33xa7TdXZYF2f6UP6Mgzfr8HKE9Rp IVPTIppzOQn3Iee5cWJewoCmc3KgXEhV2FeH0+Rn4Cq0Yj/URr9V0HvJ6qGj7QOqhewTKoeXi6q v9NuEk0/RitjfLwxQY0i5njLQlA8Bxj9lXYrlrfR8/iOO8fypJlt0NzN0NHeqteSsy55+WOzXGP gAYqxnVBcw8tPMLPvCLRtJgGm29a6JbySPKEU6iauowsm1R0z7ugGXsSxlTIDooIksOzTvQ8/Wg IrQ2S+JlAGJ3srTnYWMQaIQU+4cb9vrq6YoDsgDGKIOkOIsdhDbeeUbPkYlJ3uYrGRhS3qmTCuj e5Hc6yQGBrzHYmfy5okzqch7sCCTsuutJGQ/vUNM6eFKboU0u0WIGFtYHBs1Ak+Okn28Vn+J X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1099,Hydra:6.0.736,FMLib:17.12.80.40 definitions=2025-05-15_06,2025-05-15_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 phishscore=0 mlxscore=0 bulkscore=0 mlxlogscore=634 clxscore=1015 lowpriorityscore=0 priorityscore=1501 suspectscore=0 impostorscore=0 adultscore=0 malwarescore=0 classifier=spam authscore=0 authtc=n/a authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2505070000 definitions=main-2505150150 Received-SPF: pass client-ip=148.163.156.1; envelope-from=kowal@linux.ibm.com; helo=mx0a-001b2d01.pphosted.com X-Spam_score_int: -26 X-Spam_score: -2.7 X-Spam_bar: -- X-Spam_report: (-2.7 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 5/11/2025 10:10 PM, Nicholas Piggin wrote: > xive_tctx_pipr_present() as implemented with xive_tctx_pipr_update() > causes VP-directed (group==0) interrupt to be presented in PIPR and NSR > despite being a lower priority than the currently presented group > interrupt. > > This must not happen. The IPB bit should record the low priority VP > interrupt, but PIPR and NSR must not present the lower priority > interrupt. Reviewed-by: Michael Kowal Thanks,  MAK > > Signed-off-by: Nicholas Piggin > --- > hw/intc/xive.c | 18 +++++++++++++++++- > 1 file changed, 17 insertions(+), 1 deletion(-) > > diff --git a/hw/intc/xive.c b/hw/intc/xive.c > index bf4c0634ca..25f6c69c44 100644 > --- a/hw/intc/xive.c > +++ b/hw/intc/xive.c > @@ -228,7 +228,23 @@ void xive_tctx_pipr_update(XiveTCTX *tctx, uint8_t ring, uint8_t priority, > void xive_tctx_pipr_present(XiveTCTX *tctx, uint8_t ring, uint8_t priority, > uint8_t group_level) > { > - xive_tctx_pipr_update(tctx, ring, priority, group_level); > + /* HV_POOL ring uses HV_PHYS NSR, CPPR and PIPR registers */ > + uint8_t alt_ring = (ring == TM_QW2_HV_POOL) ? TM_QW3_HV_PHYS : ring; > + uint8_t *aregs = &tctx->regs[alt_ring]; > + uint8_t *regs = &tctx->regs[ring]; > + uint8_t pipr = xive_priority_to_pipr(priority); > + > + if (group_level == 0) { > + regs[TM_IPB] |= xive_priority_to_ipb(priority); > + if (pipr >= aregs[TM_PIPR]) { > + /* VP interrupts can come here with lower priority than PIPR */ > + return; > + } > + } > + g_assert(pipr <= xive_ipb_to_pipr(regs[TM_IPB])); > + g_assert(pipr < aregs[TM_PIPR]); > + aregs[TM_PIPR] = pipr; > + xive_tctx_notify(tctx, ring, group_level); > } > > /*