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GET /api/patches/2195684/?format=api
{ "id": 2195684, "url": "http://patchwork.ozlabs.org/api/patches/2195684/?format=api", "web_url": "http://patchwork.ozlabs.org/project/qemu-devel/patch/20260211155410.203883-11-magnuskulke@linux.microsoft.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": "<20260211155410.203883-11-magnuskulke@linux.microsoft.com>", "list_archive_url": null, "date": "2026-02-11T15:54:10", "name": "[10/10] target/i386/mshv: filter out CET bits in cpuid", "commit_ref": null, "pull_url": null, "state": "new", "archived": false, "hash": "e121b094da7d68bc8d526b660fb62da3f074939a", "submitter": { "id": 90753, "url": "http://patchwork.ozlabs.org/api/people/90753/?format=api", "name": "Magnus Kulke", "email": "magnuskulke@linux.microsoft.com" }, "delegate": null, "mbox": "http://patchwork.ozlabs.org/project/qemu-devel/patch/20260211155410.203883-11-magnuskulke@linux.microsoft.com/mbox/", "series": [ { "id": 491871, "url": "http://patchwork.ozlabs.org/api/series/491871/?format=api", "web_url": "http://patchwork.ozlabs.org/project/qemu-devel/list/?series=491871", "date": "2026-02-11T15:54:00", "name": "Support QEMU cpu models in MSHV accelerator", "version": 1, "mbox": "http://patchwork.ozlabs.org/series/491871/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/patches/2195684/comments/", "check": "pending", "checks": "http://patchwork.ozlabs.org/api/patches/2195684/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 (1024-bit key;\n unprotected) header.d=linux.microsoft.com header.i=@linux.microsoft.com\n header.a=rsa-sha256 header.s=default header.b=ZsuVw4ev;\n\tdkim-atps=neutral", "legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org\n (client-ip=209.51.188.17; helo=lists.gnu.org;\n envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org;\n receiver=patchwork.ozlabs.org)" ], "Received": [ "from lists.gnu.org (lists.gnu.org [209.51.188.17])\n\t(using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits))\n\t(No client certificate requested)\n\tby legolas.ozlabs.org (Postfix) with ESMTPS id 4fB3KP06wvz1xtV\n\tfor <incoming@patchwork.ozlabs.org>; Thu, 12 Feb 2026 03:09:29 +1100 (AEDT)", "from localhost ([::1] helo=lists1p.gnu.org)\n\tby lists.gnu.org with esmtp (Exim 4.90_1)\n\t(envelope-from <qemu-devel-bounces@nongnu.org>)\n\tid 1vqCkf-0002pn-9g; Wed, 11 Feb 2026 11:07:41 -0500", "from eggs.gnu.org ([2001:470:142:3::10])\n by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256)\n (Exim 4.90_1) (envelope-from <magnuskulke@linux.microsoft.com>)\n id 1vqCY5-0007NC-9u\n for qemu-devel@nongnu.org; Wed, 11 Feb 2026 10:54:41 -0500", "from linux.microsoft.com ([13.77.154.182])\n by eggs.gnu.org with esmtp (Exim 4.90_1)\n (envelope-from <magnuskulke@linux.microsoft.com>) id 1vqCY3-0003Sn-T9\n for qemu-devel@nongnu.org; Wed, 11 Feb 2026 10:54:41 -0500", "from DESKTOP-TUU1E5L.localdomain (unknown [167.220.208.59])\n by linux.microsoft.com (Postfix) with ESMTPSA id 2D83620B7168;\n Wed, 11 Feb 2026 07:54:37 -0800 (PST)" ], "DKIM-Filter": "OpenDKIM Filter v2.11.0 linux.microsoft.com 2D83620B7168", "DKIM-Signature": "v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com;\n s=default; t=1770825278;\n bh=HkpGIAxAdQuzfCrev9KQdB7pHBPey4VgXUf/LiB3/ZA=;\n h=From:To:Cc:Subject:Date:In-Reply-To:References:From;\n b=ZsuVw4evXQXHAL1y1HpNXhZOxfcJ/ECPdYpbsvENzG8IpSt3a3lUTiHPmOlidsi+0\n iASIc82W0XwNS48yB1bIevqp5laeUrG+S9+AcnYMNqW4xmEEnPuOw3A0SSKJBr/9wT\n GZTZfIWfdiG1DO0D76ocKsHgoz4/wGvWMwPBuV1E=", "From": "Magnus Kulke <magnuskulke@linux.microsoft.com>", "To": "qemu-devel@nongnu.org", "Cc": "Magnus Kulke <magnuskulke@linux.microsoft.com>,\n Wei Liu <liuwe@microsoft.com>, Wei Liu <wei.liu@kernel.org>,\n Zhao Liu <zhao1.liu@intel.com>, Paolo Bonzini <pbonzini@redhat.com>,\n Magnus Kulke <magnuskulke@microsoft.com>", "Subject": "[PATCH 10/10] target/i386/mshv: filter out CET bits in cpuid", "Date": "Wed, 11 Feb 2026 16:54:10 +0100", "Message-Id": "<20260211155410.203883-11-magnuskulke@linux.microsoft.com>", "X-Mailer": "git-send-email 2.34.1", "In-Reply-To": "<20260211155410.203883-1-magnuskulke@linux.microsoft.com>", "References": "<20260211155410.203883-1-magnuskulke@linux.microsoft.com>", "MIME-Version": "1.0", "Content-Transfer-Encoding": "8bit", "Received-SPF": "pass client-ip=13.77.154.182;\n envelope-from=magnuskulke@linux.microsoft.com; helo=linux.microsoft.com", "X-Spam_score_int": "-19", "X-Spam_score": "-2.0", "X-Spam_bar": "--", "X-Spam_report": "(-2.0 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1,\n DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, RCVD_IN_DNSWL_NONE=-0.0001,\n RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001,\n SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no", "X-Spam_action": "no action", "X-Mailman-Approved-At": "Wed, 11 Feb 2026 11:07:32 -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": "e46dcef1d0 introduced CET_U/CET_S xstate bits in the ExtSaveArea. The\nresponse in EBX of a 0x4,1 cpuid query will contain a size contingent on\nwhat the guest enabled in the IA32_XSS MSR (compacted xsave size).\n\nSince the MSHV accelerator currently responds with static answers to\n0x4d cpuid queries, we'll have to disable those bits, even if the host\nsupports them.\n\nSigned-off-by: Magnus Kulke <magnuskulke@linux.microsoft.com>\n---\n target/i386/mshv/mshv-cpu.c | 19 +++++++++++++++++++\n 1 file changed, 19 insertions(+)", "diff": "diff --git a/target/i386/mshv/mshv-cpu.c b/target/i386/mshv/mshv-cpu.c\nindex 3a7d9237cd..4d64c54bc6 100644\n--- a/target/i386/mshv/mshv-cpu.c\n+++ b/target/i386/mshv/mshv-cpu.c\n@@ -1781,6 +1781,25 @@ uint32_t mshv_get_supported_cpuid(uint32_t func, uint32_t idx, int reg)\n if (func == 0x01 && reg == R_ECX) {\n ret &= ~CPUID_EXT_VMX;\n }\n+\n+ /*\n+ * MSHV currently uses static CPUID intercept results for leaf 0xD.\n+ * However there are feature-responses that are dynamic based on what a\n+ * guest enables in XCR0 and XSS, such as CET shadow stack.\n+ *\n+ * A guest which doesn't know about those features yet would encounter an\n+ * unexpcted CPUID[0xD,1].EBX (compactes XSAVE size) and either fail\n+ * or gracefully degrade by not using XSAVE at all.\n+ *\n+ * To avoid this, we filter out supervisor xstate features.\n+ */\n+ if (func == 0x07 && idx == 0 && reg == R_ECX) {\n+ ret &= ~CPUID_7_0_ECX_CET_SHSTK;\n+ }\n+ if (func == 0x07 && idx == 0 && reg == R_EDX) {\n+ ret &= ~CPUID_7_0_EDX_CET_IBT;\n+ }\n+\n return ret;\n }\n \n", "prefixes": [ "10/10" ] }