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GET /api/patches/2196554/?format=api
{ "id": 2196554, "url": "http://patchwork.ozlabs.org/api/patches/2196554/?format=api", "web_url": "http://patchwork.ozlabs.org/project/qemu-devel/patch/20260214190353.29337-1-haroldknowlden@gmail.com/", "project": { "id": 14, "url": "http://patchwork.ozlabs.org/api/projects/14/?format=api", "name": "QEMU Development", "link_name": "qemu-devel", "list_id": "qemu-devel.nongnu.org", "list_email": "qemu-devel@nongnu.org", "web_url": "", "scm_url": "", "webscm_url": "", "list_archive_url": "", "list_archive_url_format": "", "commit_url_format": "" }, "msgid": "<20260214190353.29337-1-haroldknowlden@gmail.com>", "list_archive_url": null, "date": "2026-02-14T19:03:53", "name": "target/i386/kvm: Reset PMU state in kvm_init_pmu_info", "commit_ref": null, "pull_url": null, "state": "new", "archived": false, "hash": "8814be8800c010ec451cf40790f26ade8e151e27", "submitter": { "id": 92643, "url": "http://patchwork.ozlabs.org/api/people/92643/?format=api", "name": "ChaseKnowlden", "email": "haroldknowlden@gmail.com" }, "delegate": null, "mbox": "http://patchwork.ozlabs.org/project/qemu-devel/patch/20260214190353.29337-1-haroldknowlden@gmail.com/mbox/", "series": [ { "id": 492195, "url": "http://patchwork.ozlabs.org/api/series/492195/?format=api", "web_url": "http://patchwork.ozlabs.org/project/qemu-devel/list/?series=492195", "date": "2026-02-14T19:03:53", "name": "target/i386/kvm: Reset PMU state in kvm_init_pmu_info", "version": 1, "mbox": "http://patchwork.ozlabs.org/series/492195/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/patches/2196554/comments/", "check": "pending", "checks": "http://patchwork.ozlabs.org/api/patches/2196554/checks/", "tags": {}, "related": [], "headers": { "Return-Path": "<qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org>", "X-Original-To": "incoming@patchwork.ozlabs.org", "Delivered-To": "patchwork-incoming@legolas.ozlabs.org", "Authentication-Results": [ "legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256\n header.s=20230601 header.b=COeD+XbZ;\n\tdkim-atps=neutral", "legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org\n (client-ip=209.51.188.17; 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helo=mail-ot1-x32a.google.com", "X-Spam_score_int": "-20", "X-Spam_score": "-2.1", "X-Spam_bar": "--", "X-Spam_report": "(-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1,\n DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001,\n RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001,\n SPF_PASS=-0.001 autolearn=ham autolearn_force=no", "X-Spam_action": "no action", "X-Mailman-Approved-At": "Sat, 14 Feb 2026 15:19:10 -0500", "X-BeenThere": "qemu-devel@nongnu.org", "X-Mailman-Version": "2.1.29", "Precedence": "list", "List-Id": "qemu development <qemu-devel.nongnu.org>", "List-Unsubscribe": "<https://lists.nongnu.org/mailman/options/qemu-devel>,\n <mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>", "List-Archive": "<https://lists.nongnu.org/archive/html/qemu-devel>", "List-Post": "<mailto:qemu-devel@nongnu.org>", "List-Help": "<mailto:qemu-devel-request@nongnu.org?subject=help>", "List-Subscribe": "<https://lists.nongnu.org/mailman/listinfo/qemu-devel>,\n <mailto:qemu-devel-request@nongnu.org?subject=subscribe>", "Errors-To": "qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org", "Sender": "qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org" }, "content": "The static variables pmu_version, num_pmu_gp_counters, and\nnum_pmu_fixed_counters persist across different VCPU initializations.\nWhen kvm_init_pmu_info() returns early (e.g., when PMU is disabled or\nthere's a vendor mismatch), these variables retain stale values from\nprevious initializations.\n\nThis causes crashes during guest reboots, particularly with Windows XP,\nwhen kvm_put_msrs() attempts to write PMU MSRs based on the stale\npmu_version value for a CPU that doesn't actually support PMU.\n\nFix this by resetting the PMU state variables to 0 at the start of\nkvm_init_pmu_info() to ensure clean initialization for each VCPU.\n\nFixes: 4c7f05232c (\"target/i386/kvm: reset AMD PMU registers during VM reset\")\nSigned-off-by: GitHub Copilot <copilot@github.com>\n\nCo-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>\n---\n target/i386/kvm/kvm.c | 8 ++++++++\n 1 file changed, 8 insertions(+)", "diff": "diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c\nindex 9f1a4d4cbb..c636f1f487 100644\n--- a/target/i386/kvm/kvm.c\n+++ b/target/i386/kvm/kvm.c\n@@ -2193,6 +2193,14 @@ static void kvm_init_pmu_info(struct kvm_cpuid2 *cpuid, X86CPU *cpu)\n {\n CPUX86State *env = &cpu->env;\n \n+ /*\n+ * Reset PMU state to avoid stale values from previous VCPU\n+ * initializations affecting subsequent ones.\n+ */\n+ pmu_version = 0;\n+ num_pmu_gp_counters = 0;\n+ num_pmu_fixed_counters = 0;\n+\n /*\n * If KVM_CAP_PMU_CAPABILITY is not supported, there is no way to\n * disable the AMD PMU virtualization.\n", "prefixes": [] }