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{"parentUuid":"c3370ec4-0a80-419c-beb6-27e3987a4b79","isSidechain":false,"userType":"external","cwd":"/home/josie/development/forks/linux","sessionId":"0264110d-7530-4e6f-9308-60ad7d2c7434","version":"2.1.63","gitBranch":"master","slug":"quiet-shimmying-bunny","type":"user","message":{"role":"user","content":[{"tool_use_id":"toolu_01F6AEkP2qVPRKmfCiRkLgTy","type":"tool_result","content":"Message-ID: <20251117151800.248407-1-hi@josie.lol>\nFrom: Josephine Pfeiffer <hi@josie.lol>\nDate: 2025-11-17T16:18:00+01:00\nSubject: [PATCH] KVM: s390: Implement CHECK_STOP support and fix GET_MP_STATE\nList: <linux-s390.vger.kernel.org>\nSnippet: Add support for >>>KVM<<<_MP_STATE_>>>CHECK<<<_>>>STOP<<< to enable proper VM migration\r\nand error handling for s390 guests. The >>>CHECK<<<_>>>STOP<<< state represents a\r\nCPU that encountered a severe machine >>>check<<< and is halted in an error\r\nstate.\r\n\r\nThis...\n\n---\nMessage-ID: <3e4020ae-9fdb-46be-8f18-4319fc09c5cc@linux.ibm.com>\nFrom: Christian Borntraeger <borntraeger@linux.ibm.com>\nDate: 2025-11-17T19:14:57+01:00\nSubject: Re: [PATCH] KVM: s390: Implement CHECK_STOP support and fix\r\n GET_MP_STATE\nList: \nSnippet: Am 17.11.25 um 16:18 schrieb Josephine Pfeiffer:\r\n> Add support for >>>KVM<<<_MP_STATE_>>>CHECK<<<_>>>STOP<<< to enable proper VM migration\r\n> and error handling for s390 guests. The >>>CHECK<<<_>>>STOP<<< state represents a\r\n> CPU that encountered a severe...\n\n---\nMessage-ID: <fd5ad2be-f15f-425f-b8ef-087dc639024d@linux.ibm.com>\nFrom: Janosch Frank <frankja@linux.ibm.com>\nDate: 2025-11-25T19:10:43+01:00\nSubject: Re: [PATCH] KVM: s390: Implement CHECK_STOP support and fix\r\n GET_MP_STATE\nList: \nSnippet: On 11/20/25 19:28, Josephine Pfeiffer wrote:\r\n> On Mon, 17 Nov 2025 19:14:57 +0100, Christian Borntraeger wrote:\r\n>> Am 17.11.25 um 16:18 schrieb Josephine Pfeiffer:\r\n>>> Add support for >>>KVM<<<_MP_STATE_>>>CHECK<<<_>>>STOP<<< to...\n\n---\nMessage-ID: <20251211105412.207458-1-hi@josie.lol>\nFrom: Josephine Pfeiffer <hi@josie.lol>\nDate: 2025-12-11T11:54:12+01:00\nSubject: Re: [PATCH] KVM: s390: Implement CHECK_STOP support and fix GET_MP_STATE\nList: <linux-s390.vger.kernel.org>\nSnippet: ...I'll withdraw this patch and can send a cleanup patch instead to remove\r\n>>>KVM<<<_MP_STATE_>>>CHECK<<<_>>>STOP<<< from the documentation. Would that be useful?\r\n\r\nIf so, should I also remove >>>KVM<<<_MP_STATE_LOAD from the docs while...\n\n---\nMessage-ID: <20251017145207.541324466@linuxfoundation.org>\nFrom: Greg Kroah-Hartman <gregkh@linuxfoundation.org>\nDate: 2025-10-17T16:52:10+02:00\nSubject: [PATCH 6.17 155/371] KVM: arm64: Fix debug checking for np-guests using huge mappings\nList: <stable.vger.kernel.org>\nSnippet: ...arm64/>>>kvm<<</hyp/nvhe/mem_protect.c\r\n+++ b/arch/arm64/>>>kvm<<</hyp/nvhe/mem_protect.c\r\n@@ -1010,9 +1010,12 @@ static int __>>>check<<<_host_shared_guest(str\r\n \t\treturn ret;\r\n \tif (!>>>kvm<<<_pte_valid(pte))\r\n \t\treturn -ENOENT;\r\n-\tif (>>>kvm<<<_granule_size...\n\n---\nMessage-ID: <f5c07226-f748-46c9-a59b-e31494a5524f@linux.ibm.com>\nFrom: Janosch Frank <frankja@linux.ibm.com>\nDate: 2026-02-06T15:56:18+01:00\nSubject: Re: [PATCH v1 1/3] KVM: s390: Use guest address to mark guest page\r\n dirty\nList: <linux-s390.vger.kernel.org>\nSnippet: ...Janosch Frank <frankja@linux.ibm.com>\r\n\r\n\r\nWe had so many of these issues and I wonder if we should move away from \r\nmaking everything u64 and enforce type >>>checks<<< in some form.\r\n\r\n> ---\r\n>   arch/s390/>>>kvm<<</interrupt.c | 6 ++++--\r\n>   include/linux...\n\n---\nMessage-ID: <aZyHeKp2Dzzrjb5C@google.com>\nFrom: Sean Christopherson <seanjc@google.com>\nDate: 2026-02-23T08:59:36-08:00\nSubject: Re: [PATCH 1/4] KVM: nSVM: Sync next_rip to cached vmcb12 after VMRUN\r\n of L2\nList: <stable.vger.kernel.org>\nSnippet: ...A helper like __nested_vmcb_>>>check<<<_controls() isn't const, so we cast to strip\r\n> >      the const.\r\n> \r\n> I would argue that casting to strip the const is a red flag and this\r\n> scenario should have >>>stopped<<< here :P\r\n\r\nKey word...\n\n---\nMessage-ID: <20260213143815.1732675-4-tabba@google.com>\nFrom: Fuad Tabba <tabba@google.com>\nDate: 2026-02-13T14:38:14+00:00\nSubject: [PATCH v2 3/4] KVM: arm64: Fix ID register initialization for\r\n non-protected pKVM guests\nList: <stable.vger.kernel.org>\nSnippet: ...Consequently, `>>>kvm<<<_has_feat()` >>>checks<<< at EL2 fail (return 0) for\r\nnon-protected VMs. This breaks logic that relies on feature detection,\r\nsuch as `ctxt_has_tcrx()` for TCR2_EL1 support. As a result, certain\r\nsystem registers (e.g., TCR2...\n\n---\nMessage-ID: <20260212090252.158689-3-tabba@google.com>\nFrom: Fuad Tabba <tabba@google.com>\nDate: 2026-02-12T09:02:51+00:00\nSubject: [PATCH v1 2/3] KVM: arm64: Fix ID register initialization for\r\n non-protected pKVM guests\nList: <stable.vger.kernel.org>\nSnippet: ...Consequently, `>>>kvm<<<_has_feat()` >>>checks<<< at EL2 fail (return 0) for\r\nnon-protected VMs. This breaks logic that relies on feature detection,\r\nsuch as `ctxt_has_tcrx()` for TCR2_EL1 support. As a result, certain\r\nsystem registers (e.g., TCR2...\n\n---\nMessage-ID: <ftjb625b4wsz5vdty3fcxqanuxriiqcewqkzp2ml2hc4eojuoc@ewhboiiqmcd4>\nFrom: Yosry Ahmed <yosry@kernel.org>\nDate: 2026-02-21T09:11:24+00:00\nSubject: Re: [PATCH 1/4] KVM: nSVM: Sync next_rip to cached vmcb12 after\r\n VMRUN of L2\nList: <stable.vger.kernel.org>\nSnippet: ...A helper like __nested_vmcb_>>>check<<<_controls() isn't const, so we cast to strip\r\n>      the const.\r\n\r\nI would argue that casting to strip the const is a red flag and this\r\nscenario should have >>>stopped<<< here :P\r\n\r\nThat being...\n\n---\nMessage-ID: <20260209142256.925538451@linuxfoundation.org>\nFrom: Greg Kroah-Hartman <gregkh@linuxfoundation.org>\nDate: 2026-02-09T15:24:24+01:00\nSubject: [PATCH 5.10 03/41] KVM: Dont clobber irqfd routing type when deassigning irqfd\nList: <stable.vger.kernel.org>\nSnippet: ...As evidenced by the x86 and\r\narm64 bugs, and another bug in >>>kvm<<<_arch_update_irqfd_routing() (see below),\r\nclobbering the entry type without notifying arch code is surprising and\r\nerror prone.\r\n\r\nAs a bonus, >>>checking<<< that the irqfd is...\n\n---\nMessage-ID: <20260209142321.665714257@linuxfoundation.org>\nFrom: Greg Kroah-Hartman <gregkh@linuxfoundation.org>\nDate: 2026-02-09T15:21:46+01:00\nSubject: [PATCH 6.18 033/175] KVM: Dont clobber irqfd routing type when deassigning irqfd\nList: <stable.vger.kernel.org>\nSnippet: ...As evidenced by the x86 and\r\narm64 bugs, and another bug in >>>kvm<<<_arch_update_irqfd_routing() (see below),\r\nclobbering the entry type without notifying arch code is surprising and\r\nerror prone.\r\n\r\nAs a bonus, >>>checking<<< that the irqfd is...\n\n---\nMessage-ID: <20260209142310.936877761@linuxfoundation.org>\nFrom: Greg Kroah-Hartman <gregkh@linuxfoundation.org>\nDate: 2026-02-09T15:22:49+01:00\nSubject: [PATCH 6.12 020/113] KVM: Dont clobber irqfd routing type when deassigning irqfd\nList: <stable.vger.kernel.org>\nSnippet: ...As evidenced by the x86 and\r\narm64 bugs, and another bug in >>>kvm<<<_arch_update_irqfd_routing() (see below),\r\nclobbering the entry type without notifying arch code is surprising and\r\nerror prone.\r\n\r\nAs a bonus, >>>checking<<< that the irqfd is...\n\n---\nMessage-ID: <20260209142302.181522464@linuxfoundation.org>\nFrom: Greg Kroah-Hartman <gregkh@linuxfoundation.org>\nDate: 2026-02-09T15:23:35+01:00\nSubject: [PATCH 6.1 07/69] KVM: Dont clobber irqfd routing type when deassigning irqfd\nList: <stable.vger.kernel.org>\nSnippet: ...As evidenced by the x86 and\r\narm64 bugs, and another bug in >>>kvm<<<_arch_update_irqfd_routing() (see below),\r\nclobbering the entry type without notifying arch code is surprising and\r\nerror prone.\r\n\r\nAs a bonus, >>>checking<<< that the irqfd is...\n\n---\nMessage-ID: <20260209142305.221319663@linuxfoundation.org>\nFrom: Greg Kroah-Hartman <gregkh@linuxfoundation.org>\nDate: 2026-02-09T15:23:35+01:00\nSubject: [PATCH 6.6 12/86] KVM: Dont clobber irqfd routing type when deassigning irqfd\nList: <stable.vger.kernel.org>\nSnippet: ...As evidenced by the x86 and\r\narm64 bugs, and another bug in >>>kvm<<<_arch_update_irqfd_routing() (see below),\r\nclobbering the entry type without notifying arch code is surprising and\r\nerror prone.\r\n\r\nAs a bonus, >>>checking<<< that the irqfd is...\nShell cwd was reset to /home/josie/development/forks/linux","is_error":false}]},"uuid":"797180e8-554f-4f8b-9d6d-e2ea5811781c","timestamp":"2026-03-01T10:00:46.571Z","toolUseResult":{"stdout":"Message-ID: <20251117151800.248407-1-hi@josie.lol>\nFrom: Josephine Pfeiffer <hi@josie.lol>\nDate: 2025-11-17T16:18:00+01:00\nSubject: [PATCH] KVM: s390: Implement CHECK_STOP support and fix GET_MP_STATE\nList: <linux-s390.vger.kernel.org>\nSnippet: Add support for >>>KVM<<<_MP_STATE_>>>CHECK<<<_>>>STOP<<< to enable proper VM migration\r\nand error handling for s390 guests. The >>>CHECK<<<_>>>STOP<<< state represents a\r\nCPU that encountered a severe machine >>>check<<< and is halted in an error\r\nstate.\r\n\r\nThis...\n\n---\nMessage-ID: <3e4020ae-9fdb-46be-8f18-4319fc09c5cc@linux.ibm.com>\nFrom: Christian Borntraeger <borntraeger@linux.ibm.com>\nDate: 2025-11-17T19:14:57+01:00\nSubject: Re: [PATCH] KVM: s390: Implement CHECK_STOP support and fix\r\n GET_MP_STATE\nList: \nSnippet: Am 17.11.25 um 16:18 schrieb Josephine Pfeiffer:\r\n> Add support for >>>KVM<<<_MP_STATE_>>>CHECK<<<_>>>STOP<<< to enable proper VM migration\r\n> and error handling for s390 guests. The >>>CHECK<<<_>>>STOP<<< state represents a\r\n> CPU that encountered a severe...\n\n---\nMessage-ID: <fd5ad2be-f15f-425f-b8ef-087dc639024d@linux.ibm.com>\nFrom: Janosch Frank <frankja@linux.ibm.com>\nDate: 2025-11-25T19:10:43+01:00\nSubject: Re: [PATCH] KVM: s390: Implement CHECK_STOP support and fix\r\n GET_MP_STATE\nList: \nSnippet: On 11/20/25 19:28, Josephine Pfeiffer wrote:\r\n> On Mon, 17 Nov 2025 19:14:57 +0100, Christian Borntraeger wrote:\r\n>> Am 17.11.25 um 16:18 schrieb Josephine Pfeiffer:\r\n>>> Add support for >>>KVM<<<_MP_STATE_>>>CHECK<<<_>>>STOP<<< to...\n\n---\nMessage-ID: <20251211105412.207458-1-hi@josie.lol>\nFrom: Josephine Pfeiffer <hi@josie.lol>\nDate: 2025-12-11T11:54:12+01:00\nSubject: Re: [PATCH] KVM: s390: Implement CHECK_STOP support and fix GET_MP_STATE\nList: <linux-s390.vger.kernel.org>\nSnippet: ...I'll withdraw this patch and can send a cleanup patch instead to remove\r\n>>>KVM<<<_MP_STATE_>>>CHECK<<<_>>>STOP<<< from the documentation. Would that be useful?\r\n\r\nIf so, should I also remove >>>KVM<<<_MP_STATE_LOAD from the docs while...\n\n---\nMessage-ID: <20251017145207.541324466@linuxfoundation.org>\nFrom: Greg Kroah-Hartman <gregkh@linuxfoundation.org>\nDate: 2025-10-17T16:52:10+02:00\nSubject: [PATCH 6.17 155/371] KVM: arm64: Fix debug checking for np-guests using huge mappings\nList: <stable.vger.kernel.org>\nSnippet: ...arm64/>>>kvm<<</hyp/nvhe/mem_protect.c\r\n+++ b/arch/arm64/>>>kvm<<</hyp/nvhe/mem_protect.c\r\n@@ -1010,9 +1010,12 @@ static int __>>>check<<<_host_shared_guest(str\r\n \t\treturn ret;\r\n \tif (!>>>kvm<<<_pte_valid(pte))\r\n \t\treturn -ENOENT;\r\n-\tif (>>>kvm<<<_granule_size...\n\n---\nMessage-ID: <f5c07226-f748-46c9-a59b-e31494a5524f@linux.ibm.com>\nFrom: Janosch Frank <frankja@linux.ibm.com>\nDate: 2026-02-06T15:56:18+01:00\nSubject: Re: [PATCH v1 1/3] KVM: s390: Use guest address to mark guest page\r\n dirty\nList: <linux-s390.vger.kernel.org>\nSnippet: ...Janosch Frank <frankja@linux.ibm.com>\r\n\r\n\r\nWe had so many of these issues and I wonder if we should move away from \r\nmaking everything u64 and enforce type >>>checks<<< in some form.\r\n\r\n> ---\r\n>   arch/s390/>>>kvm<<</interrupt.c | 6 ++++--\r\n>   include/linux...\n\n---\nMessage-ID: <aZyHeKp2Dzzrjb5C@google.com>\nFrom: Sean Christopherson <seanjc@google.com>\nDate: 2026-02-23T08:59:36-08:00\nSubject: Re: [PATCH 1/4] KVM: nSVM: Sync next_rip to cached vmcb12 after VMRUN\r\n of L2\nList: <stable.vger.kernel.org>\nSnippet: ...A helper like __nested_vmcb_>>>check<<<_controls() isn't const, so we cast to strip\r\n> >      the const.\r\n> \r\n> I would argue that casting to strip the const is a red flag and this\r\n> scenario should have >>>stopped<<< here :P\r\n\r\nKey word...\n\n---\nMessage-ID: <20260213143815.1732675-4-tabba@google.com>\nFrom: Fuad Tabba <tabba@google.com>\nDate: 2026-02-13T14:38:14+00:00\nSubject: [PATCH v2 3/4] KVM: arm64: Fix ID register initialization for\r\n non-protected pKVM guests\nList: <stable.vger.kernel.org>\nSnippet: ...Consequently, `>>>kvm<<<_has_feat()` >>>checks<<< at EL2 fail (return 0) for\r\nnon-protected VMs. This breaks logic that relies on feature detection,\r\nsuch as `ctxt_has_tcrx()` for TCR2_EL1 support. As a result, certain\r\nsystem registers (e.g., TCR2...\n\n---\nMessage-ID: <20260212090252.158689-3-tabba@google.com>\nFrom: Fuad Tabba <tabba@google.com>\nDate: 2026-02-12T09:02:51+00:00\nSubject: [PATCH v1 2/3] KVM: arm64: Fix ID register initialization for\r\n non-protected pKVM guests\nList: <stable.vger.kernel.org>\nSnippet: ...Consequently, `>>>kvm<<<_has_feat()` >>>checks<<< at EL2 fail (return 0) for\r\nnon-protected VMs. This breaks logic that relies on feature detection,\r\nsuch as `ctxt_has_tcrx()` for TCR2_EL1 support. As a result, certain\r\nsystem registers (e.g., TCR2...\n\n---\nMessage-ID: <ftjb625b4wsz5vdty3fcxqanuxriiqcewqkzp2ml2hc4eojuoc@ewhboiiqmcd4>\nFrom: Yosry Ahmed <yosry@kernel.org>\nDate: 2026-02-21T09:11:24+00:00\nSubject: Re: [PATCH 1/4] KVM: nSVM: Sync next_rip to cached vmcb12 after\r\n VMRUN of L2\nList: <stable.vger.kernel.org>\nSnippet: ...A helper like __nested_vmcb_>>>check<<<_controls() isn't const, so we cast to strip\r\n>      the const.\r\n\r\nI would argue that casting to strip the const is a red flag and this\r\nscenario should have >>>stopped<<< here :P\r\n\r\nThat being...\n\n---\nMessage-ID: <20260209142256.925538451@linuxfoundation.org>\nFrom: Greg Kroah-Hartman <gregkh@linuxfoundation.org>\nDate: 2026-02-09T15:24:24+01:00\nSubject: [PATCH 5.10 03/41] KVM: Dont clobber irqfd routing type when deassigning irqfd\nList: <stable.vger.kernel.org>\nSnippet: ...As evidenced by the x86 and\r\narm64 bugs, and another bug in >>>kvm<<<_arch_update_irqfd_routing() (see below),\r\nclobbering the entry type without notifying arch code is surprising and\r\nerror prone.\r\n\r\nAs a bonus, >>>checking<<< that the irqfd is...\n\n---\nMessage-ID: <20260209142321.665714257@linuxfoundation.org>\nFrom: Greg Kroah-Hartman <gregkh@linuxfoundation.org>\nDate: 2026-02-09T15:21:46+01:00\nSubject: [PATCH 6.18 033/175] KVM: Dont clobber irqfd routing type when deassigning irqfd\nList: <stable.vger.kernel.org>\nSnippet: ...As evidenced by the x86 and\r\narm64 bugs, and another bug in >>>kvm<<<_arch_update_irqfd_routing() (see below),\r\nclobbering the entry type without notifying arch code is surprising and\r\nerror prone.\r\n\r\nAs a bonus, >>>checking<<< that the irqfd is...\n\n---\nMessage-ID: <20260209142310.936877761@linuxfoundation.org>\nFrom: Greg Kroah-Hartman <gregkh@linuxfoundation.org>\nDate: 2026-02-09T15:22:49+01:00\nSubject: [PATCH 6.12 020/113] KVM: Dont clobber irqfd routing type when deassigning irqfd\nList: <stable.vger.kernel.org>\nSnippet: ...As evidenced by the x86 and\r\narm64 bugs, and another bug in >>>kvm<<<_arch_update_irqfd_routing() (see below),\r\nclobbering the entry type without notifying arch code is surprising and\r\nerror prone.\r\n\r\nAs a bonus, >>>checking<<< that the irqfd is...\n\n---\nMessage-ID: <20260209142302.181522464@linuxfoundation.org>\nFrom: Greg Kroah-Hartman <gregkh@linuxfoundation.org>\nDate: 2026-02-09T15:23:35+01:00\nSubject: [PATCH 6.1 07/69] KVM: Dont clobber irqfd routing type when deassigning irqfd\nList: <stable.vger.kernel.org>\nSnippet: ...As evidenced by the x86 and\r\narm64 bugs, and another bug in >>>kvm<<<_arch_update_irqfd_routing() (see below),\r\nclobbering the entry type without notifying arch code is surprising and\r\nerror prone.\r\n\r\nAs a bonus, >>>checking<<< that the irqfd is...\n\n---\nMessage-ID: <20260209142305.221319663@linuxfoundation.org>\nFrom: Greg Kroah-Hartman <gregkh@linuxfoundation.org>\nDate: 2026-02-09T15:23:35+01:00\nSubject: [PATCH 6.6 12/86] KVM: Dont clobber irqfd routing type when deassigning irqfd\nList: <stable.vger.kernel.org>\nSnippet: ...As evidenced by the x86 and\r\narm64 bugs, and another bug in >>>kvm<<<_arch_update_irqfd_routing() (see below),\r\nclobbering the entry type without notifying arch code is surprising and\r\nerror prone.\r\n\r\nAs a bonus, >>>checking<<< that the irqfd is...","stderr":"\nShell cwd was reset to /home/josie/development/forks/linux","interrupted":false,"isImage":false,"noOutputExpected":false},"sourceToolAssistantUUID":"c3370ec4-0a80-419c-beb6-27e3987a4b79"}
{"parentUuid":"797180e8-554f-4f8b-9d6d-e2ea5811781c","isSidechain":false,"userType":"external","cwd":"/home/josie/development/forks/linux","sessionId":"0264110d-7530-4e6f-9308-60ad7d2c7434","version":"2.1.63","gitBranch":"master","slug":"quiet-shimmying-bunny","message":{"model":"claude-opus-4-6","id":"msg_018AsJLWuegMhLtoYKKmhffY","type":"message","role":"assistant","content":[{"type":"text","text":"Found it. The first 4 results are your CHECK_STOP thread. Let me pull the full thread:"}],"stop_reason":null,"stop_sequence":null,"usage":{"input_tokens":1,"cache_creation_input_tokens":3505,"cache_read_input_tokens":139379,"cache_creation":{"ephemeral_5m_input_tokens":0,"ephemeral_1h_input_tokens":3505},"output_tokens":1,"service_tier":"standard","inference_geo":"not_available"}},"requestId":"req_011CYcAbNEQ81r5v7XfEk7fU","type":"assistant","uuid":"78f72e6b-621c-4c14-b70a-3939583e79fc","timestamp":"2026-03-01T10:00:50.242Z"}
{"parentUuid":"78f72e6b-621c-4c14-b70a-3939583e79fc","isSidechain":false,"userType":"external","cwd":"/home/josie/development/forks/linux","sessionId":"0264110d-7530-4e6f-9308-60ad7d2c7434","version":"2.1.63","gitBranch":"master","slug":"quiet-shimmying-bunny","message":{"model":"claude-opus-4-6","id":"msg_018AsJLWuegMhLtoYKKmhffY","type":"message","role":"assistant","content":[{"type":"tool_use","id":"toolu_01RKTrkvLKfDnXmTvTirPDtR","name":"Bash","input":{"command":"cd ~/development/personal/kernel-mail-mcp && printf '{\"jsonrpc\":\"2.0\",\"id\":1,\"method\":\"initialize\",\"params\":{\"protocolVersion\":\"2024-11-05\",\"capabilities\":{},\"clientInfo\":{\"name\":\"test\",\"version\":\"0.1\"}}}\\n{\"jsonrpc\":\"2.0\",\"method\":\"notifications/initialized\"}\\n{\"jsonrpc\":\"2.0\",\"id\":4,\"method\":\"tools/call\",\"params\":{\"name\":\"get_mail_thread\",\"arguments\":{\"message_id\":\"<20251117151800.248407-1-hi@josie.lol>\"}}}\\n' | timeout 30 uv run python -m kernel_mail_mcp 2>/dev/null | python3 -c \"\nimport sys, json\nfor line in sys.stdin:\n    line = line.strip()\n    if not line: continue\n    try:\n        d = json.loads(line)\n        if d.get('id') == 4:\n            for c in d['result']['content']:\n                print(c['text'])\n    except: pass\n\"","description":"Get full CHECK_STOP thread","timeout":30000},"caller":{"type":"direct"}}],"stop_reason":"tool_use","stop_sequence":null,"usage":{"input_tokens":1,"cache_creation_input_tokens":3505,"cache_read_input_tokens":139379,"output_tokens":373,"server_tool_use":{"web_search_requests":0,"web_fetch_requests":0},"service_tier":"standard","cache_creation":{"ephemeral_1h_input_tokens":3505,"ephemeral_5m_input_tokens":0},"inference_geo":"","iterations":[],"speed":"standard"}},"requestId":"req_011CYcAbNEQ81r5v7XfEk7fU","type":"assistant","uuid":"da72bd96-df91-42f7-852d-c7db3fc2dde2","timestamp":"2026-03-01T10:00:52.950Z"}
{"parentUuid":"da72bd96-df91-42f7-852d-c7db3fc2dde2","isSidechain":false,"userType":"external","cwd":"/home/josie/development/forks/linux","sessionId":"0264110d-7530-4e6f-9308-60ad7d2c7434","version":"2.1.63","gitBranch":"master","slug":"quiet-shimmying-bunny","type":"progress","data":{"type":"hook_progress","hookEvent":"PreToolUse","hookName":"PreToolUse:Bash","command":"python3 ${CLAUDE_PLUGIN_ROOT}/hooks/pretooluse.py"},"toolUseID":"toolu_01RKTrkvLKfDnXmTvTirPDtR","parentToolUseID":"toolu_01RKTrkvLKfDnXmTvTirPDtR","uuid":"7729005b-3d38-4dfd-9950-fd384d831c65","timestamp":"2026-03-01T10:00:52.953Z"}
{"parentUuid":"7729005b-3d38-4dfd-9950-fd384d831c65","isSidechain":false,"userType":"external","cwd":"/home/josie/development/forks/linux","sessionId":"0264110d-7530-4e6f-9308-60ad7d2c7434","version":"2.1.63","gitBranch":"master","slug":"quiet-shimmying-bunny","type":"progress","data":{"type":"hook_progress","hookEvent":"PostToolUse","hookName":"PostToolUse:Bash","command":"python3 ${CLAUDE_PLUGIN_ROOT}/hooks/posttooluse.py"},"parentToolUseID":"toolu_01RKTrkvLKfDnXmTvTirPDtR","toolUseID":"toolu_01RKTrkvLKfDnXmTvTirPDtR","timestamp":"2026-03-01T10:00:54.416Z","uuid":"2769bfa6-4005-4820-bfd8-fc48875e9585"}
{"parentUuid":"da72bd96-df91-42f7-852d-c7db3fc2dde2","isSidechain":false,"userType":"external","cwd":"/home/josie/development/forks/linux","sessionId":"0264110d-7530-4e6f-9308-60ad7d2c7434","version":"2.1.63","gitBranch":"master","slug":"quiet-shimmying-bunny","type":"user","message":{"role":"user","content":[{"tool_use_id":"toolu_01RKTrkvLKfDnXmTvTirPDtR","type":"tool_result","content":"Thread (2 messages):\n\nMessage-ID: <20251117151800.248407-1-hi@josie.lol>\nFrom: Josephine Pfeiffer <hi@josie.lol>\nDate: 2025-11-17T16:18:00+01:00\nSubject: [PATCH] KVM: s390: Implement CHECK_STOP support and fix GET_MP_STATE\n\nAdd support for KVM_MP_STATE_CHECK_STOP to enable proper VM migration\r\nand error handling for s390 guests. The CHECK_STOP state represents a\r\nCPU that encountered a severe machine check and is halted in an error\r\nstate.\r\n\r\nThis implementation adds:\r\n- CPUSTAT_CHECK_STOP flag to track check-stopped CPUs\r\n- is_vcpu_check_stopped() helper macro for state checking\r\n- kvm_s390_vcpu_check_stop() function to transition CPUs to CHECK_STOP\r\n- Integration with Protected VM Ultravisor (PV_CPU_STATE_CHKSTP)\r\n- Interrupt blocking for check-stopped CPUs in deliverable_irqs()\r\n- Recovery path enabling CHECK_STOP -> OPERATING transitions\r\n- Proper state precedence where CHECK_STOP takes priority over STOPPED\r\n\r\nSigned-off-by: Josephine Pfeiffer <hi@josie.lol>\r\n---\r\n arch/s390/include/asm/kvm_host_types.h |  1 +\r\n arch/s390/kvm/interrupt.c              |  3 ++\r\n arch/s390/kvm/kvm-s390.c               | 72 ++++++++++++++++++++++----\r\n arch/s390/kvm/kvm-s390.h               |  6 +++\r\n arch/s390/kvm/sigp.c                   |  8 ++-\r\n 5 files changed, 77 insertions(+), 13 deletions(-)\r\n\r\ndiff --git a/arch/s390/include/asm/kvm_host_types.h b/arch/s390/include/asm/kvm_host_types.h\r\nindex 1394d3fb648f..a86e326a2eee 100644\r\n--- a/arch/s390/include/asm/kvm_host_types.h\r\n+++ b/arch/s390/include/asm/kvm_host_types.h\r\n@@ -111,6 +111,7 @@ struct mcck_volatile_info {\r\n \t((((sie_block)->sidad & SIDAD_SIZE_MASK) + 1) * PAGE_SIZE)\r\n \r\n #define CPUSTAT_STOPPED    0x80000000\r\n+#define CPUSTAT_CHECK_STOP 0x40000000\r\n #define CPUSTAT_WAIT\t   0x10000000\r\n #define CPUSTAT_ECALL_PEND 0x08000000\r\n #define CPUSTAT_STOP_INT   0x04000000\r\ndiff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c\r\nindex c62a868cf2b6..e09e5aff318a 100644\r\n--- a/arch/s390/kvm/interrupt.c\r\n+++ b/arch/s390/kvm/interrupt.c\r\n@@ -361,6 +361,9 @@ static unsigned long deliverable_irqs(struct kvm_vcpu *vcpu)\r\n \tif (!active_mask)\r\n \t\treturn 0;\r\n \r\n+\tif (kvm_s390_test_cpuflags(vcpu, CPUSTAT_CHECK_STOP))\r\n+\t\treturn 0;\r\n+\r\n \tif (psw_extint_disabled(vcpu))\r\n \t\tactive_mask &= ~IRQ_PEND_EXT_MASK;\r\n \tif (psw_ioint_disabled(vcpu))\r\ndiff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c\r\nindex 16ba04062854..25eb3bebdfea 100644\r\n--- a/arch/s390/kvm/kvm-s390.c\r\n+++ b/arch/s390/kvm/kvm-s390.c\r\n@@ -4465,16 +4465,17 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,\r\n int kvm_arch_vcpu_ioctl_get_mpstate(struct kvm_vcpu *vcpu,\r\n \t\t\t\t    struct kvm_mp_state *mp_state)\r\n {\r\n-\tint ret;\r\n-\r\n \tvcpu_load(vcpu);\r\n \r\n-\t/* CHECK_STOP and LOAD are not supported yet */\r\n-\tret = is_vcpu_stopped(vcpu) ? KVM_MP_STATE_STOPPED :\r\n-\t\t\t\t      KVM_MP_STATE_OPERATING;\r\n+\tif (is_vcpu_check_stopped(vcpu))\r\n+\t\tmp_state->mp_state = KVM_MP_STATE_CHECK_STOP;\r\n+\telse if (is_vcpu_stopped(vcpu))\r\n+\t\tmp_state->mp_state = KVM_MP_STATE_STOPPED;\r\n+\telse\r\n+\t\tmp_state->mp_state = KVM_MP_STATE_OPERATING;\r\n \r\n \tvcpu_put(vcpu);\r\n-\treturn ret;\r\n+\treturn 0;\r\n }\r\n \r\n int kvm_arch_vcpu_ioctl_set_mpstate(struct kvm_vcpu *vcpu,\r\n@@ -4502,7 +4503,8 @@ int kvm_arch_vcpu_ioctl_set_mpstate(struct kvm_vcpu *vcpu,\r\n \t\trc = kvm_s390_pv_set_cpu_state(vcpu, PV_CPU_STATE_OPR_LOAD);\r\n \t\tbreak;\r\n \tcase KVM_MP_STATE_CHECK_STOP:\r\n-\t\tfallthrough;\t/* CHECK_STOP and LOAD are not supported yet */\r\n+\t\trc = kvm_s390_vcpu_check_stop(vcpu);\r\n+\t\tbreak;\r\n \tdefault:\r\n \t\trc = -ENXIO;\r\n \t}\r\n@@ -5488,7 +5490,7 @@ int kvm_s390_vcpu_start(struct kvm_vcpu *vcpu)\r\n {\r\n \tint i, online_vcpus, r = 0, started_vcpus = 0;\r\n \r\n-\tif (!is_vcpu_stopped(vcpu))\r\n+\tif (!is_vcpu_stopped(vcpu) && !is_vcpu_check_stopped(vcpu))\r\n \t\treturn 0;\r\n \r\n \ttrace_kvm_s390_vcpu_start_stop(vcpu->vcpu_id, 1);\r\n@@ -5506,7 +5508,9 @@ int kvm_s390_vcpu_start(struct kvm_vcpu *vcpu)\r\n \t}\r\n \r\n \tfor (i = 0; i < online_vcpus; i++) {\r\n-\t\tif (!is_vcpu_stopped(kvm_get_vcpu(vcpu->kvm, i)))\r\n+\t\tstruct kvm_vcpu *tmp = kvm_get_vcpu(vcpu->kvm, i);\r\n+\r\n+\t\tif (!is_vcpu_stopped(tmp) && !is_vcpu_check_stopped(tmp))\r\n \t\t\tstarted_vcpus++;\r\n \t}\r\n \r\n@@ -5522,7 +5526,7 @@ int kvm_s390_vcpu_start(struct kvm_vcpu *vcpu)\r\n \t\t__disable_ibs_on_all_vcpus(vcpu->kvm);\r\n \t}\r\n \r\n-\tkvm_s390_clear_cpuflags(vcpu, CPUSTAT_STOPPED);\r\n+\tkvm_s390_clear_cpuflags(vcpu, CPUSTAT_STOPPED | CPUSTAT_CHECK_STOP);\r\n \t/*\r\n \t * The real PSW might have changed due to a RESTART interpreted by the\r\n \t * ultravisor. We block all interrupts and let the next sie exit\r\n@@ -5566,7 +5570,11 @@ int kvm_s390_vcpu_stop(struct kvm_vcpu *vcpu)\r\n \t * now that the SIGP STOP and SIGP STOP AND STORE STATUS orders\r\n \t * have been fully processed. This will ensure that the VCPU\r\n \t * is kept BUSY if another VCPU is inquiring with SIGP SENSE.\r\n+\t *\r\n+\t * Clear CHECK_STOP before setting STOPPED to handle the state\r\n+\t * transition CHECK_STOP -> STOPPED.\r\n \t */\r\n+\tkvm_s390_clear_cpuflags(vcpu, CPUSTAT_CHECK_STOP);\r\n \tkvm_s390_set_cpuflags(vcpu, CPUSTAT_STOPPED);\r\n \tkvm_s390_clear_stop_irq(vcpu);\r\n \r\n@@ -5575,7 +5583,7 @@ int kvm_s390_vcpu_stop(struct kvm_vcpu *vcpu)\r\n \tfor (i = 0; i < online_vcpus; i++) {\r\n \t\tstruct kvm_vcpu *tmp = kvm_get_vcpu(vcpu->kvm, i);\r\n \r\n-\t\tif (!is_vcpu_stopped(tmp)) {\r\n+\t\tif (!is_vcpu_stopped(tmp) && !is_vcpu_check_stopped(tmp)) {\r\n \t\t\tstarted_vcpus++;\r\n \t\t\tstarted_vcpu = tmp;\r\n \t\t}\r\n@@ -5593,6 +5601,48 @@ int kvm_s390_vcpu_stop(struct kvm_vcpu *vcpu)\r\n \treturn 0;\r\n }\r\n \r\n+int kvm_s390_vcpu_check_stop(struct kvm_vcpu *vcpu)\r\n+{\r\n+\tint r = 0;\r\n+\r\n+\t/* trace: 0=stop, 1=start, 2=check-stop */\r\n+\ttrace_kvm_s390_vcpu_start_stop(vcpu->vcpu_id, 2);\r\n+\t/* Only one cpu at a time may enter/leave the STOPPED/CHECK_STOP state. */\r\n+\tspin_lock(&vcpu->kvm->arch.start_stop_lock);\r\n+\r\n+\tif (kvm_s390_test_cpuflags(vcpu, CPUSTAT_CHECK_STOP)) {\r\n+\t\t__disable_ibs_on_vcpu(vcpu);\r\n+\t\tgoto out;\r\n+\t}\r\n+\r\n+\tif (kvm_s390_pv_cpu_is_protected(vcpu)) {\r\n+\t\tr = kvm_s390_pv_set_cpu_state(vcpu, PV_CPU_STATE_CHKSTP);\r\n+\t\tif (r) {\r\n+\t\t\tspin_unlock(&vcpu->kvm->arch.start_stop_lock);\r\n+\t\t\treturn r;\r\n+\t\t}\r\n+\t}\r\n+\r\n+\t/*\r\n+\t * Clear STOPPED if it was set, CHECK_STOP takes precedence.\r\n+\t * This allows the transition STOPPED -> CHECK_STOP.\r\n+\t * The reverse transition CHECK_STOP -> STOPPED is handled by\r\n+\t * kvm_s390_vcpu_stop() which clears CHECK_STOP before setting STOPPED.\r\n+\t */\r\n+\tif (kvm_s390_test_cpuflags(vcpu, CPUSTAT_STOPPED))\r\n+\t\tkvm_s390_clear_cpuflags(vcpu, CPUSTAT_STOPPED);\r\n+\r\n+\tkvm_s390_set_cpuflags(vcpu, CPUSTAT_CHECK_STOP);\r\n+\tkvm_s390_clear_stop_irq(vcpu);\r\n+\t__disable_ibs_on_vcpu(vcpu);\r\n+\r\n+out:\r\n+\tspin_unlock(&vcpu->kvm->arch.start_stop_lock);\r\n+\treturn r;\r\n+}\r\n+\r\n static int kvm_vcpu_ioctl_enable_cap(struct kvm_vcpu *vcpu,\r\n \t\t\t\t     struct kvm_enable_cap *cap)\r\n {\r\ndiff --git a/arch/s390/kvm/kvm-s390.h b/arch/s390/kvm/kvm-s390.h\r\nindex c44fe0c3a097..6851f52bdddb 100644\r\n--- a/arch/s390/kvm/kvm-s390.h\r\n+++ b/arch/s390/kvm/kvm-s390.h\r\n@@ -98,6 +98,11 @@ static inline int is_vcpu_stopped(struct kvm_vcpu *vcpu)\r\n \treturn kvm_s390_test_cpuflags(vcpu, CPUSTAT_STOPPED);\r\n }\r\n \r\n+static inline int is_vcpu_check_stopped(struct kvm_vcpu *vcpu)\r\n+{\r\n+\treturn kvm_s390_test_cpuflags(vcpu, CPUSTAT_CHECK_STOP);\r\n+}\r\n+\r\n static inline int is_vcpu_idle(struct kvm_vcpu *vcpu)\r\n {\r\n \treturn test_bit(vcpu->vcpu_idx, vcpu->kvm->arch.idle_mask);\r\n@@ -451,6 +456,7 @@ int kvm_s390_store_status_unloaded(struct kvm_vcpu *vcpu, unsigned long addr);\r\n int kvm_s390_vcpu_store_status(struct kvm_vcpu *vcpu, unsigned long addr);\r\n int kvm_s390_vcpu_start(struct kvm_vcpu *vcpu);\r\n int kvm_s390_vcpu_stop(struct kvm_vcpu *vcpu);\r\n+int kvm_s390_vcpu_check_stop(struct kvm_vcpu *vcpu);\r\n void kvm_s390_vcpu_block(struct kvm_vcpu *vcpu);\r\n void kvm_s390_vcpu_unblock(struct kvm_vcpu *vcpu);\r\n bool kvm_s390_vcpu_sie_inhibited(struct kvm_vcpu *vcpu);\r\ndiff --git a/arch/s390/kvm/sigp.c b/arch/s390/kvm/sigp.c\r\nindex 55c34cb35428..03f1084f63cf 100644\r\n--- a/arch/s390/kvm/sigp.c\r\n+++ b/arch/s390/kvm/sigp.c\r\n@@ -21,16 +21,19 @@ static int __sigp_sense(struct kvm_vcpu *vcpu, struct kvm_vcpu *dst_vcpu,\r\n \t\t\tu64 *reg)\r\n {\r\n \tconst bool stopped = kvm_s390_test_cpuflags(dst_vcpu, CPUSTAT_STOPPED);\r\n+\tconst bool check_stopped = kvm_s390_test_cpuflags(dst_vcpu, CPUSTAT_CHECK_STOP);\r\n \tint rc;\r\n \tint ext_call_pending;\r\n \r\n \text_call_pending = kvm_s390_ext_call_pending(dst_vcpu);\r\n-\tif (!stopped && !ext_call_pending)\r\n+\tif (!stopped && !check_stopped && !ext_call_pending)\r\n \t\trc = SIGP_CC_ORDER_CODE_ACCEPTED;\r\n \telse {\r\n \t\t*reg &= 0xffffffff00000000UL;\r\n \t\tif (ext_call_pending)\r\n \t\t\t*reg |= SIGP_STATUS_EXT_CALL_PENDING;\r\n+\t\tif (check_stopped)\r\n+\t\t\t*reg |= SIGP_STATUS_CHECK_STOP;\r\n \t\tif (stopped)\r\n \t\t\t*reg |= SIGP_STATUS_STOPPED;\r\n \t\trc = SIGP_CC_STATUS_STORED;\r\n@@ -221,7 +224,8 @@ static int __sigp_sense_running(struct kvm_vcpu *vcpu,\r\n \t\treturn SIGP_CC_STATUS_STORED;\r\n \t}\r\n \r\n-\tif (kvm_s390_test_cpuflags(dst_vcpu, CPUSTAT_RUNNING)) {\r\n+\tif (kvm_s390_test_cpuflags(dst_vcpu, CPUSTAT_RUNNING) &&\r\n+\t    !kvm_s390_test_cpuflags(dst_vcpu, CPUSTAT_CHECK_STOP)) {\r\n \t\t/* running */\r\n \t\trc = SIGP_CC_ORDER_CODE_ACCEPTED;\r\n \t} else {\r\n-- \r\n2.51.2\r\n\r\n\r\n\r\n\n\n===\n\nMessage-ID: <3e4020ae-9fdb-46be-8f18-4319fc09c5cc@linux.ibm.com>\nFrom: Christian Borntraeger <borntraeger@linux.ibm.com>\nDate: 2025-11-17T19:14:57+01:00\nSubject: Re: [PATCH] KVM: s390: Implement CHECK_STOP support and fix\r\n GET_MP_STATE\n\nAm 17.11.25 um 16:18 schrieb Josephine Pfeiffer:\r\n> Add support for KVM_MP_STATE_CHECK_STOP to enable proper VM migration\r\n> and error handling for s390 guests. The CHECK_STOP state represents a\r\n> CPU that encountered a severe machine check and is halted in an error\r\n> state.\r\n\r\nI think the patch description is misleading. We do have proper VM\r\nmigration and we also have error handling in the kvm module. The host\r\nmachine check handler will forward guest machine checks to the guest.\r\nThis logic  is certainly not perfect but kind of good enough for most\r\ncases.\r\nNow: The architecture defines that state and the interface is certainly\r\nthere. So implementing it will allow userspace to put a CPU into checkstop\r\nstate if you ever need that. We also have a checkstop state that you\r\ncan put a secure CPU in.\r\n\r\nThe usecase is dubious though. The only case of the options from POP\r\nchapter11 that makes sense to me in a virtualized environment is an exigent\r\nmachine check but a problem to actually deliver that (multiple reasons,\r\nlike the OS has machine checks disabled in PSW, or the prefix register\r\nis broken).\r\n\r\nSo I am curious, do you have any specific usecase in mind?\r\nI assume you have a related QEMU patch somewhere?\r\n\r\n> \r\n> This implementation adds:\r\n> - CPUSTAT_CHECK_STOP flag to track check-stopped CPUs\r\n> - is_vcpu_check_stopped() helper macro for state checking\r\n> - kvm_s390_vcpu_check_stop() function to transition CPUs to CHECK_STOP\r\n> - Integration with Protected VM Ultravisor (PV_CPU_STATE_CHKSTP)\r\n> - Interrupt blocking for check-stopped CPUs in deliverable_irqs()\r\n> - Recovery path enabling CHECK_STOP -> OPERATING transitions\r\n> - Proper state precedence where CHECK_STOP takes priority over STOPPED\r\n> \r\n> Signed-off-by: Josephine Pfeiffer <hi@josie.lol>\r\n> ---\r\n>   arch/s390/include/asm/kvm_host_types.h |  1 +\r\n>   arch/s390/kvm/interrupt.c              |  3 ++\r\n>   arch/s390/kvm/kvm-s390.c               | 72 ++++++++++++++++++++++----\r\n>   arch/s390/kvm/kvm-s390.h               |  6 +++\r\n>   arch/s390/kvm/sigp.c                   |  8 ++-\r\n>   5 files changed, 77 insertions(+), 13 deletions(-)\r\n> \r\n\r\n From a quick glance the patch in general does not look wrong but at least this is wrong:> diff --git a/arch/s390/include/asm/kvm_host_types.h b/arch/s390/include/asm/kvm_host_types.h\r\n> index 1394d3fb648f..a86e326a2eee 100644\r\n> --- a/arch/s390/include/asm/kvm_host_types.h\r\n> +++ b/arch/s390/include/asm/kvm_host_types.h\r\n> @@ -111,6 +111,7 @@ struct mcck_volatile_info {\r\n>   \t((((sie_block)->sidad & SIDAD_SIZE_MASK) + 1) * PAGE_SIZE)\r\n>   \r\n>   #define CPUSTAT_STOPPED    0x80000000\r\n> +#define CPUSTAT_CHECK_STOP 0x40000000\r\nBit 1 of the sie control block is a hardware defined bit and\r\nits meaning is not checkstop, so this is not the right way to do it.\r\nLets first clarify your usecase so that we can see what the right way forward is.\r\n\r\nChristian\nShell cwd was reset to /home/josie/development/forks/linux","is_error":false}]},"uuid":"e63e8e6a-56dc-4d6e-863c-5f7d81ea8386","timestamp":"2026-03-01T10:00:54.415Z","toolUseResult":{"stdout":"Thread (2 messages):\n\nMessage-ID: <20251117151800.248407-1-hi@josie.lol>\nFrom: Josephine Pfeiffer <hi@josie.lol>\nDate: 2025-11-17T16:18:00+01:00\nSubject: [PATCH] KVM: s390: Implement CHECK_STOP support and fix GET_MP_STATE\n\nAdd support for KVM_MP_STATE_CHECK_STOP to enable proper VM migration\r\nand error handling for s390 guests. The CHECK_STOP state represents a\r\nCPU that encountered a severe machine check and is halted in an error\r\nstate.\r\n\r\nThis implementation adds:\r\n- CPUSTAT_CHECK_STOP flag to track check-stopped CPUs\r\n- is_vcpu_check_stopped() helper macro for state checking\r\n- kvm_s390_vcpu_check_stop() function to transition CPUs to CHECK_STOP\r\n- Integration with Protected VM Ultravisor (PV_CPU_STATE_CHKSTP)\r\n- Interrupt blocking for check-stopped CPUs in deliverable_irqs()\r\n- Recovery path enabling CHECK_STOP -> OPERATING transitions\r\n- Proper state precedence where CHECK_STOP takes priority over STOPPED\r\n\r\nSigned-off-by: Josephine Pfeiffer <hi@josie.lol>\r\n---\r\n arch/s390/include/asm/kvm_host_types.h |  1 +\r\n arch/s390/kvm/interrupt.c              |  3 ++\r\n arch/s390/kvm/kvm-s390.c               | 72 ++++++++++++++++++++++----\r\n arch/s390/kvm/kvm-s390.h               |  6 +++\r\n arch/s390/kvm/sigp.c                   |  8 ++-\r\n 5 files changed, 77 insertions(+), 13 deletions(-)\r\n\r\ndiff --git a/arch/s390/include/asm/kvm_host_types.h b/arch/s390/include/asm/kvm_host_types.h\r\nindex 1394d3fb648f..a86e326a2eee 100644\r\n--- a/arch/s390/include/asm/kvm_host_types.h\r\n+++ b/arch/s390/include/asm/kvm_host_types.h\r\n@@ -111,6 +111,7 @@ struct mcck_volatile_info {\r\n \t((((sie_block)->sidad & SIDAD_SIZE_MASK) + 1) * PAGE_SIZE)\r\n \r\n #define CPUSTAT_STOPPED    0x80000000\r\n+#define CPUSTAT_CHECK_STOP 0x40000000\r\n #define CPUSTAT_WAIT\t   0x10000000\r\n #define CPUSTAT_ECALL_PEND 0x08000000\r\n #define CPUSTAT_STOP_INT   0x04000000\r\ndiff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c\r\nindex c62a868cf2b6..e09e5aff318a 100644\r\n--- a/arch/s390/kvm/interrupt.c\r\n+++ b/arch/s390/kvm/interrupt.c\r\n@@ -361,6 +361,9 @@ static unsigned long deliverable_irqs(struct kvm_vcpu *vcpu)\r\n \tif (!active_mask)\r\n \t\treturn 0;\r\n \r\n+\tif (kvm_s390_test_cpuflags(vcpu, CPUSTAT_CHECK_STOP))\r\n+\t\treturn 0;\r\n+\r\n \tif (psw_extint_disabled(vcpu))\r\n \t\tactive_mask &= ~IRQ_PEND_EXT_MASK;\r\n \tif (psw_ioint_disabled(vcpu))\r\ndiff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c\r\nindex 16ba04062854..25eb3bebdfea 100644\r\n--- a/arch/s390/kvm/kvm-s390.c\r\n+++ b/arch/s390/kvm/kvm-s390.c\r\n@@ -4465,16 +4465,17 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,\r\n int kvm_arch_vcpu_ioctl_get_mpstate(struct kvm_vcpu *vcpu,\r\n \t\t\t\t    struct kvm_mp_state *mp_state)\r\n {\r\n-\tint ret;\r\n-\r\n \tvcpu_load(vcpu);\r\n \r\n-\t/* CHECK_STOP and LOAD are not supported yet */\r\n-\tret = is_vcpu_stopped(vcpu) ? KVM_MP_STATE_STOPPED :\r\n-\t\t\t\t      KVM_MP_STATE_OPERATING;\r\n+\tif (is_vcpu_check_stopped(vcpu))\r\n+\t\tmp_state->mp_state = KVM_MP_STATE_CHECK_STOP;\r\n+\telse if (is_vcpu_stopped(vcpu))\r\n+\t\tmp_state->mp_state = KVM_MP_STATE_STOPPED;\r\n+\telse\r\n+\t\tmp_state->mp_state = KVM_MP_STATE_OPERATING;\r\n \r\n \tvcpu_put(vcpu);\r\n-\treturn ret;\r\n+\treturn 0;\r\n }\r\n \r\n int kvm_arch_vcpu_ioctl_set_mpstate(struct kvm_vcpu *vcpu,\r\n@@ -4502,7 +4503,8 @@ int kvm_arch_vcpu_ioctl_set_mpstate(struct kvm_vcpu *vcpu,\r\n \t\trc = kvm_s390_pv_set_cpu_state(vcpu, PV_CPU_STATE_OPR_LOAD);\r\n \t\tbreak;\r\n \tcase KVM_MP_STATE_CHECK_STOP:\r\n-\t\tfallthrough;\t/* CHECK_STOP and LOAD are not supported yet */\r\n+\t\trc = kvm_s390_vcpu_check_stop(vcpu);\r\n+\t\tbreak;\r\n \tdefault:\r\n \t\trc = -ENXIO;\r\n \t}\r\n@@ -5488,7 +5490,7 @@ int kvm_s390_vcpu_start(struct kvm_vcpu *vcpu)\r\n {\r\n \tint i, online_vcpus, r = 0, started_vcpus = 0;\r\n \r\n-\tif (!is_vcpu_stopped(vcpu))\r\n+\tif (!is_vcpu_stopped(vcpu) && !is_vcpu_check_stopped(vcpu))\r\n \t\treturn 0;\r\n \r\n \ttrace_kvm_s390_vcpu_start_stop(vcpu->vcpu_id, 1);\r\n@@ -5506,7 +5508,9 @@ int kvm_s390_vcpu_start(struct kvm_vcpu *vcpu)\r\n \t}\r\n \r\n \tfor (i = 0; i < online_vcpus; i++) {\r\n-\t\tif (!is_vcpu_stopped(kvm_get_vcpu(vcpu->kvm, i)))\r\n+\t\tstruct kvm_vcpu *tmp = kvm_get_vcpu(vcpu->kvm, i);\r\n+\r\n+\t\tif (!is_vcpu_stopped(tmp) && !is_vcpu_check_stopped(tmp))\r\n \t\t\tstarted_vcpus++;\r\n \t}\r\n \r\n@@ -5522,7 +5526,7 @@ int kvm_s390_vcpu_start(struct kvm_vcpu *vcpu)\r\n \t\t__disable_ibs_on_all_vcpus(vcpu->kvm);\r\n \t}\r\n \r\n-\tkvm_s390_clear_cpuflags(vcpu, CPUSTAT_STOPPED);\r\n+\tkvm_s390_clear_cpuflags(vcpu, CPUSTAT_STOPPED | CPUSTAT_CHECK_STOP);\r\n \t/*\r\n \t * The real PSW might have changed due to a RESTART interpreted by the\r\n \t * ultravisor. We block all interrupts and let the next sie exit\r\n@@ -5566,7 +5570,11 @@ int kvm_s390_vcpu_stop(struct kvm_vcpu *vcpu)\r\n \t * now that the SIGP STOP and SIGP STOP AND STORE STATUS orders\r\n \t * have been fully processed. This will ensure that the VCPU\r\n \t * is kept BUSY if another VCPU is inquiring with SIGP SENSE.\r\n+\t *\r\n+\t * Clear CHECK_STOP before setting STOPPED to handle the state\r\n+\t * transition CHECK_STOP -> STOPPED.\r\n \t */\r\n+\tkvm_s390_clear_cpuflags(vcpu, CPUSTAT_CHECK_STOP);\r\n \tkvm_s390_set_cpuflags(vcpu, CPUSTAT_STOPPED);\r\n \tkvm_s390_clear_stop_irq(vcpu);\r\n \r\n@@ -5575,7 +5583,7 @@ int kvm_s390_vcpu_stop(struct kvm_vcpu *vcpu)\r\n \tfor (i = 0; i < online_vcpus; i++) {\r\n \t\tstruct kvm_vcpu *tmp = kvm_get_vcpu(vcpu->kvm, i);\r\n \r\n-\t\tif (!is_vcpu_stopped(tmp)) {\r\n+\t\tif (!is_vcpu_stopped(tmp) && !is_vcpu_check_stopped(tmp)) {\r\n \t\t\tstarted_vcpus++;\r\n \t\t\tstarted_vcpu = tmp;\r\n \t\t}\r\n@@ -5593,6 +5601,48 @@ int kvm_s390_vcpu_stop(struct kvm_vcpu *vcpu)\r\n \treturn 0;\r\n }\r\n \r\n+int kvm_s390_vcpu_check_stop(struct kvm_vcpu *vcpu)\r\n+{\r\n+\tint r = 0;\r\n+\r\n+\t/* trace: 0=stop, 1=start, 2=check-stop */\r\n+\ttrace_kvm_s390_vcpu_start_stop(vcpu->vcpu_id, 2);\r\n+\t/* Only one cpu at a time may enter/leave the STOPPED/CHECK_STOP state. */\r\n+\tspin_lock(&vcpu->kvm->arch.start_stop_lock);\r\n+\r\n+\tif (kvm_s390_test_cpuflags(vcpu, CPUSTAT_CHECK_STOP)) {\r\n+\t\t__disable_ibs_on_vcpu(vcpu);\r\n+\t\tgoto out;\r\n+\t}\r\n+\r\n+\tif (kvm_s390_pv_cpu_is_protected(vcpu)) {\r\n+\t\tr = kvm_s390_pv_set_cpu_state(vcpu, PV_CPU_STATE_CHKSTP);\r\n+\t\tif (r) {\r\n+\t\t\tspin_unlock(&vcpu->kvm->arch.start_stop_lock);\r\n+\t\t\treturn r;\r\n+\t\t}\r\n+\t}\r\n+\r\n+\t/*\r\n+\t * Clear STOPPED if it was set, CHECK_STOP takes precedence.\r\n+\t * This allows the transition STOPPED -> CHECK_STOP.\r\n+\t * The reverse transition CHECK_STOP -> STOPPED is handled by\r\n+\t * kvm_s390_vcpu_stop() which clears CHECK_STOP before setting STOPPED.\r\n+\t */\r\n+\tif (kvm_s390_test_cpuflags(vcpu, CPUSTAT_STOPPED))\r\n+\t\tkvm_s390_clear_cpuflags(vcpu, CPUSTAT_STOPPED);\r\n+\r\n+\tkvm_s390_set_cpuflags(vcpu, CPUSTAT_CHECK_STOP);\r\n+\tkvm_s390_clear_stop_irq(vcpu);\r\n+\t__disable_ibs_on_vcpu(vcpu);\r\n+\r\n+out:\r\n+\tspin_unlock(&vcpu->kvm->arch.start_stop_lock);\r\n+\treturn r;\r\n+}\r\n+\r\n static int kvm_vcpu_ioctl_enable_cap(struct kvm_vcpu *vcpu,\r\n \t\t\t\t     struct kvm_enable_cap *cap)\r\n {\r\ndiff --git a/arch/s390/kvm/kvm-s390.h b/arch/s390/kvm/kvm-s390.h\r\nindex c44fe0c3a097..6851f52bdddb 100644\r\n--- a/arch/s390/kvm/kvm-s390.h\r\n+++ b/arch/s390/kvm/kvm-s390.h\r\n@@ -98,6 +98,11 @@ static inline int is_vcpu_stopped(struct kvm_vcpu *vcpu)\r\n \treturn kvm_s390_test_cpuflags(vcpu, CPUSTAT_STOPPED);\r\n }\r\n \r\n+static inline int is_vcpu_check_stopped(struct kvm_vcpu *vcpu)\r\n+{\r\n+\treturn kvm_s390_test_cpuflags(vcpu, CPUSTAT_CHECK_STOP);\r\n+}\r\n+\r\n static inline int is_vcpu_idle(struct kvm_vcpu *vcpu)\r\n {\r\n \treturn test_bit(vcpu->vcpu_idx, vcpu->kvm->arch.idle_mask);\r\n@@ -451,6 +456,7 @@ int kvm_s390_store_status_unloaded(struct kvm_vcpu *vcpu, unsigned long addr);\r\n int kvm_s390_vcpu_store_status(struct kvm_vcpu *vcpu, unsigned long addr);\r\n int kvm_s390_vcpu_start(struct kvm_vcpu *vcpu);\r\n int kvm_s390_vcpu_stop(struct kvm_vcpu *vcpu);\r\n+int kvm_s390_vcpu_check_stop(struct kvm_vcpu *vcpu);\r\n void kvm_s390_vcpu_block(struct kvm_vcpu *vcpu);\r\n void kvm_s390_vcpu_unblock(struct kvm_vcpu *vcpu);\r\n bool kvm_s390_vcpu_sie_inhibited(struct kvm_vcpu *vcpu);\r\ndiff --git a/arch/s390/kvm/sigp.c b/arch/s390/kvm/sigp.c\r\nindex 55c34cb35428..03f1084f63cf 100644\r\n--- a/arch/s390/kvm/sigp.c\r\n+++ b/arch/s390/kvm/sigp.c\r\n@@ -21,16 +21,19 @@ static int __sigp_sense(struct kvm_vcpu *vcpu, struct kvm_vcpu *dst_vcpu,\r\n \t\t\tu64 *reg)\r\n {\r\n \tconst bool stopped = kvm_s390_test_cpuflags(dst_vcpu, CPUSTAT_STOPPED);\r\n+\tconst bool check_stopped = kvm_s390_test_cpuflags(dst_vcpu, CPUSTAT_CHECK_STOP);\r\n \tint rc;\r\n \tint ext_call_pending;\r\n \r\n \text_call_pending = kvm_s390_ext_call_pending(dst_vcpu);\r\n-\tif (!stopped && !ext_call_pending)\r\n+\tif (!stopped && !check_stopped && !ext_call_pending)\r\n \t\trc = SIGP_CC_ORDER_CODE_ACCEPTED;\r\n \telse {\r\n \t\t*reg &= 0xffffffff00000000UL;\r\n \t\tif (ext_call_pending)\r\n \t\t\t*reg |= SIGP_STATUS_EXT_CALL_PENDING;\r\n+\t\tif (check_stopped)\r\n+\t\t\t*reg |= SIGP_STATUS_CHECK_STOP;\r\n \t\tif (stopped)\r\n \t\t\t*reg |= SIGP_STATUS_STOPPED;\r\n \t\trc = SIGP_CC_STATUS_STORED;\r\n@@ -221,7 +224,8 @@ static int __sigp_sense_running(struct kvm_vcpu *vcpu,\r\n \t\treturn SIGP_CC_STATUS_STORED;\r\n \t}\r\n \r\n-\tif (kvm_s390_test_cpuflags(dst_vcpu, CPUSTAT_RUNNING)) {\r\n+\tif (kvm_s390_test_cpuflags(dst_vcpu, CPUSTAT_RUNNING) &&\r\n+\t    !kvm_s390_test_cpuflags(dst_vcpu, CPUSTAT_CHECK_STOP)) {\r\n \t\t/* running */\r\n \t\trc = SIGP_CC_ORDER_CODE_ACCEPTED;\r\n \t} else {\r\n-- \r\n2.51.2\r\n\r\n\r\n\r\n\n\n===\n\nMessage-ID: <3e4020ae-9fdb-46be-8f18-4319fc09c5cc@linux.ibm.com>\nFrom: Christian Borntraeger <borntraeger@linux.ibm.com>\nDate: 2025-11-17T19:14:57+01:00\nSubject: Re: [PATCH] KVM: s390: Implement CHECK_STOP support and fix\r\n GET_MP_STATE\n\nAm 17.11.25 um 16:18 schrieb Josephine Pfeiffer:\r\n> Add support for KVM_MP_STATE_CHECK_STOP to enable proper VM migration\r\n> and error handling for s390 guests. The CHECK_STOP state represents a\r\n> CPU that encountered a severe machine check and is halted in an error\r\n> state.\r\n\r\nI think the patch description is misleading. We do have proper VM\r\nmigration and we also have error handling in the kvm module. The host\r\nmachine check handler will forward guest machine checks to the guest.\r\nThis logic  is certainly not perfect but kind of good enough for most\r\ncases.\r\nNow: The architecture defines that state and the interface is certainly\r\nthere. So implementing it will allow userspace to put a CPU into checkstop\r\nstate if you ever need that. We also have a checkstop state that you\r\ncan put a secure CPU in.\r\n\r\nThe usecase is dubious though. The only case of the options from POP\r\nchapter11 that makes sense to me in a virtualized environment is an exigent\r\nmachine check but a problem to actually deliver that (multiple reasons,\r\nlike the OS has machine checks disabled in PSW, or the prefix register\r\nis broken).\r\n\r\nSo I am curious, do you have any specific usecase in mind?\r\nI assume you have a related QEMU patch somewhere?\r\n\r\n> \r\n> This implementation adds:\r\n> - CPUSTAT_CHECK_STOP flag to track check-stopped CPUs\r\n> - is_vcpu_check_stopped() helper macro for state checking\r\n> - kvm_s390_vcpu_check_stop() function to transition CPUs to CHECK_STOP\r\n> - Integration with Protected VM Ultravisor (PV_CPU_STATE_CHKSTP)\r\n> - Interrupt blocking for check-stopped CPUs in deliverable_irqs()\r\n> - Recovery path enabling CHECK_STOP -> OPERATING transitions\r\n> - Proper state precedence where CHECK_STOP takes priority over STOPPED\r\n> \r\n> Signed-off-by: Josephine Pfeiffer <hi@josie.lol>\r\n> ---\r\n>   arch/s390/include/asm/kvm_host_types.h |  1 +\r\n>   arch/s390/kvm/interrupt.c              |  3 ++\r\n>   arch/s390/kvm/kvm-s390.c               | 72 ++++++++++++++++++++++----\r\n>   arch/s390/kvm/kvm-s390.h               |  6 +++\r\n>   arch/s390/kvm/sigp.c                   |  8 ++-\r\n>   5 files changed, 77 insertions(+), 13 deletions(-)\r\n> \r\n\r\n From a quick glance the patch in general does not look wrong but at least this is wrong:> diff --git a/arch/s390/include/asm/kvm_host_types.h b/arch/s390/include/asm/kvm_host_types.h\r\n> index 1394d3fb648f..a86e326a2eee 100644\r\n> --- a/arch/s390/include/asm/kvm_host_types.h\r\n> +++ b/arch/s390/include/asm/kvm_host_types.h\r\n> @@ -111,6 +111,7 @@ struct mcck_volatile_info {\r\n>   \t((((sie_block)->sidad & SIDAD_SIZE_MASK) + 1) * PAGE_SIZE)\r\n>   \r\n>   #define CPUSTAT_STOPPED    0x80000000\r\n> +#define CPUSTAT_CHECK_STOP 0x40000000\r\nBit 1 of the sie control block is a hardware defined bit and\r\nits meaning is not checkstop, so this is not the right way to do it.\r\nLets first clarify your usecase so that we can see what the right way forward is.\r\n\r\nChristian","stderr":"\nShell cwd was reset to /home/josie/development/forks/linux","interrupted":false,"isImage":false,"noOutputExpected":false},"sourceToolAssistantUUID":"da72bd96-df91-42f7-852d-c7db3fc2dde2"}
{"parentUuid":"e63e8e6a-56dc-4d6e-863c-5f7d81ea8386","isSidechain":false,"userType":"external","cwd":"/home/josie/development/forks/linux","sessionId":"0264110d-7530-4e6f-9308-60ad7d2c7434","version":"2.1.63","gitBranch":"master","slug":"quiet-shimmying-bunny","message":{"model":"claude-opus-4-6","id":"msg_01Mo46RhyeBNUggVGZTAxq8E","type":"message","role":"assistant","content":[{"type":"text","text":"There's the thread. The thread tracker found 2 messages directly linked (your patch + Christian's reply). Let me also grab Janosch's reply and your follow-up which were in separate threads by reference:"}],"stop_reason":null,"stop_sequence":null,"usage":{"input_tokens":1,"cache_creation_input_tokens":5647,"cache_read_input_tokens":142884,"cache_creation":{"ephemeral_5m_input_tokens":0,"ephemeral_1h_input_tokens":5647},"output_tokens":1,"service_tier":"standard","inference_geo":"not_available"}},"requestId":"req_011CYcAbwpFLvtBS4kqKLruN","type":"assistant","uuid":"efd07fd7-036f-4eef-a570-5a41044aa6fa","timestamp":"2026-03-01T10:00:59.162Z"}
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