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boundary="------------KqZgUygnldzEy1wu4Ae322et" Message-ID: <332f765f-a988-4a41-85aa-9cdd92d97e92@linux.ibm.com> Date: Tue, 25 Aug 2026 11:23:20 -0500 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] ppc/xive: Trigger the pending interrupt for a guest after migration To: milesg@linux.ibm.com, Gautam Menghani , clg@kaod.org, harshpb@linux.ibm.com Cc: qemu-ppc@nongnu.org, qemu-devel@nongnu.org References: <20260824070353.40016-1-gautam@linux.ibm.com> <7a5a04d4524d64a0768ed57486da20cec62cafc4.camel@linux.ibm.com> Content-Language: en-US From: Mike Kowal In-Reply-To: <7a5a04d4524d64a0768ed57486da20cec62cafc4.camel@linux.ibm.com> X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=TfimcxQh c=1 sm=1 tr=0 ts=6a8dc17b cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=V8glGbnc2Ofi9Qvn3v5h:22 a=r77TgQKjGQsHNAKrUKIA:9 a=VnNF1IyMAAAA:8 a=fjbThTX60DlU4Y5F95YA:9 a=QEXdDO2ut3YA:10 a=PE73ikAbuXiEWt2sRg8A:9 a=2QLYeOQBcrQJzgmM:21 a=_W_S_7VecoQA:10 a=lqcHg5cX4UMA:10 X-Proofpoint-Spam-Info: AW1haW4tMjYwODI1MDEzNiBTYWx0ZWRfXwuPWU28c2jbt 3YviwYL4KEjnT0gIIVa4ZBV+YZ6r+803xxnSmq/PhBZ0hajDob+KjCOfWxOfV2/KGnN3jcWihyS dyFBEjjcuJi/2Zc+saqL7XjjPCwTR+U= X-Proofpoint-GUID: gXNPPa6QNLhuWJsOF9zBnghWBB42TfLF X-Proofpoint-ORIG-GUID: gXNPPa6QNLhuWJsOF9zBnghWBB42TfLF X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODI1MDEzNiBTYWx0ZWRfX0GfbNHK6rVlX DSh1RvV7o2d//FXxbUTpFa8lLQMsuW8vsvK3KUYQMVc9v7DH4NHRIDjroGWGKeHCQDejX8rDuhZ azASJemy+//1O+SlFuBpDiZkQgkMbCkAQp4af+p9dYGt5WN5YiIz+kdyyv4AnGffzq2d132gKzz pFozbLR5vTzBQ4pCYwCMVyx3S64ZVI2qkCJqTz7JsrXiv0g/7CWk4Or5clp/xepjYFF9oXO/TdU fHRG+Kda13/MyNOluLHvj+K5w39BoQYz2Kq/f3SZ6+h8ocI9cx6U+iCgw5d3MberlqktRjwzWrn pNqARDG6xQCdZZACCigGORseUVCN43p7U5s849mcypvWpTj2yUuiKJSLOZTqZhLVE1Jh1BxhF4k QEdDVbT14PEWiTEu3te7Aqjms1AKKFYZ14cKAJv3r0Kzz8XjIz/s15mXdjv5RotE+ccKHN1+fbw ai6rnkJe7C3TnydgTPA== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-25_04,2026-08-24_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 spamscore=0 bulkscore=0 malwarescore=0 priorityscore=1501 lowpriorityscore=0 clxscore=1011 phishscore=0 impostorscore=0 adultscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608250136 Received-SPF: pass client-ip=148.163.158.5; envelope-from=kowal@linux.ibm.com; helo=mx0b-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, HTML_MESSAGE=0.001, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=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: 2.1.29 Precedence: list List-Id: qemu development 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 This is a multi-part message in MIME format. --------------KqZgUygnldzEy1wu4Ae322et Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 8/25/2026 9:42 AM, Miles Glenn wrote: > Mike Kowal, can you please review this? > > Thanks, > > Glenn > > On Mon, 2026-08-24 at 12:33 +0530, Gautam Menghani wrote: >> When a KVM guest is migrated to another LPAR while a stress-ng workload >> is running, lockups are seen when the guest resumes on the destination >> LPAR. This root cause is that if there was a pending interrupt for a cpu >> on the source machine but it was not presented yet when the migration >> started, the interrupt is not retriggered on the destination LPAR. This >> is evident when running 'info pic' on the destination LPAR: >> >> $ virsh qemu-monitor-command --hmp migrate 'info pic' | grep -e OS -e MSI >> CPU[0000]: OS 00 ff 00 ff ff 00 ff ff 80000400 >> CPU[0001]: OS 00 ff 00 ff ff 00 ff ff 80000401 >> CPU[0002]: OS 00 ff 00 ff ff 00 ff ff 80000402 >> CPU[0003]: OS 00 ff 00 ff ff 00 ff ff 80000403 >> CPU[0004]: OS 00 ff 00 ff ff 00 ff ff 80000404 >> CPU[0005]: OS 00 ff 00 ff ff 00 ff ff 80000405 >> CPU[0006]: OS 80 ff 02 ff ff 00 ff 06 80000406 >> CPU[0007]: OS 00 ff 00 ff ff 00 ff ff 80000407 >> 00000000 MSI -- 00000010 0/6 3071/16384 @3710000 ^1 [ 80000010 80000010 80000010 80000010 80000010 ^00000000 ] >> 00000001 MSI -- 00000010 1/6 1852/16384 @3980000 ^1 [ 80000010 80000033 80000033 80000033 80000033 ^00000000 ] >> 00000002 MSI -- 00000010 2/6 4424/16384 @40c0000 ^1 [ 80000020 80000020 80000020 80000010 80000010 ^00000000 ] >> 00000003 MSI -- 00000010 3/6 1913/16384 @4220000 ^1 [ 80000010 80000032 80000010 80000010 80000010 ^00000000 ] >> 00000004 MSI -- 00000010 4/6 2946/16384 @4360000 ^1 [ 80000010 80000010 80000010 80000010 80000010 ^00000000 ] >> 00000005 MSI -- 00000010 5/6 2313/16384 @44a0000 ^1 [ 80000010 80000010 80000010 80000010 80000010 ^00000000 ] >> 00000006 MSI P- 00000010 6/6 5825/16384 @45f0000 ^1 [ 80000024 80000024 80000024 80000010 80000016 ^00000000 ] >> 00000007 MSI -- 00000010 7/6 2346/16384 @4760000 ^1 [ 80000032 80000032 80000010 80000032 80000032 ^00000000 ] >> >> Fix this by calling xive_tctx_pipr_set() in >> vmstate_xive_tctx_post_load(), which ends up calling qemu_irq_raise() to >> present the interrupt. >> >> Signed-off-by: Gautam Menghani >> --- >> hw/intc/xive.c | 3 +++ >> 1 file changed, 3 insertions(+) >> >> diff --git a/hw/intc/xive.c b/hw/intc/xive.c >> index f473e6ac77..712498d4af 100644 >> --- a/hw/intc/xive.c >> +++ b/hw/intc/xive.c >> @@ -1080,6 +1080,9 @@ static int vmstate_xive_tctx_post_load(void *opaque, int version_id) >> error_report_err(local_err); >> return ret; >> } >> + } else { >> + uint8_t pipr = tctx->regs[TM_QW1_OS + TM_PIPR]; >> + xive_tctx_pipr_set(tctx, TM_QW1_OS, pipr, 0); >> } >> >> return 0; Reviewed-by: Michael Kowal --------------KqZgUygnldzEy1wu4Ae322et Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: 7bit


On 8/25/2026 9:42 AM, Miles Glenn wrote:
Mike Kowal, can you please review this?

Thanks,

Glenn

On Mon, 2026-08-24 at 12:33 +0530, Gautam Menghani wrote:

When a KVM guest is migrated to another LPAR while a stress-ng workload
is running, lockups are seen when the guest resumes on the destination
LPAR. This root cause is that if there was a pending interrupt for a cpu
on the source machine but it was not presented yet when the migration
started, the interrupt is not retriggered on the destination LPAR. This
is evident when running 'info pic' on the destination LPAR:

$ virsh qemu-monitor-command --hmp migrate 'info pic' | grep -e OS -e MSI
CPU[0000]:   OS    00   ff  00    ff   ff  00  ff   ff  80000400
CPU[0001]:   OS    00   ff  00    ff   ff  00  ff   ff  80000401
CPU[0002]:   OS    00   ff  00    ff   ff  00  ff   ff  80000402
CPU[0003]:   OS    00   ff  00    ff   ff  00  ff   ff  80000403
CPU[0004]:   OS    00   ff  00    ff   ff  00  ff   ff  80000404
CPU[0005]:   OS    00   ff  00    ff   ff  00  ff   ff  80000405
CPU[0006]:   OS    80   ff  02    ff   ff  00  ff   06  80000406
CPU[0007]:   OS    00   ff  00    ff   ff  00  ff   ff  80000407
  00000000 MSI --    00000010   0/6   3071/16384 @3710000 ^1 [ 80000010 80000010 80000010 80000010 80000010 ^00000000 ]
  00000001 MSI --    00000010   1/6   1852/16384 @3980000 ^1 [ 80000010 80000033 80000033 80000033 80000033 ^00000000 ]
  00000002 MSI --    00000010   2/6   4424/16384 @40c0000 ^1 [ 80000020 80000020 80000020 80000010 80000010 ^00000000 ]
  00000003 MSI --    00000010   3/6   1913/16384 @4220000 ^1 [ 80000010 80000032 80000010 80000010 80000010 ^00000000 ]
  00000004 MSI --    00000010   4/6   2946/16384 @4360000 ^1 [ 80000010 80000010 80000010 80000010 80000010 ^00000000 ]
  00000005 MSI --    00000010   5/6   2313/16384 @44a0000 ^1 [ 80000010 80000010 80000010 80000010 80000010 ^00000000 ]
  00000006 MSI P-    00000010   6/6   5825/16384 @45f0000 ^1 [ 80000024 80000024 80000024 80000010 80000016 ^00000000 ]
  00000007 MSI --    00000010   7/6   2346/16384 @4760000 ^1 [ 80000032 80000032 80000010 80000032 80000032 ^00000000 ]

Fix this by calling xive_tctx_pipr_set() in
vmstate_xive_tctx_post_load(), which ends up calling qemu_irq_raise() to
present the interrupt.

Signed-off-by: Gautam Menghani <gautam@linux.ibm.com>
---
 hw/intc/xive.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/hw/intc/xive.c b/hw/intc/xive.c
index f473e6ac77..712498d4af 100644
--- a/hw/intc/xive.c
+++ b/hw/intc/xive.c
@@ -1080,6 +1080,9 @@ static int vmstate_xive_tctx_post_load(void *opaque, int version_id)
             error_report_err(local_err);
             return ret;
         }
+    } else {
+        uint8_t pipr = tctx->regs[TM_QW1_OS + TM_PIPR];
+        xive_tctx_pipr_set(tctx, TM_QW1_OS, pipr, 0);
     }
 
     return 0;


Reviewed-by: Michael Kowal <kowal@linux.ibm.com>





    

  


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