From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D4F7F1E9B37; Sat, 16 Aug 2025 14:44:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.19 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755355492; cv=none; b=HPBfvjLPJKez8/3p73nzEC6II3vEoVD1jQ4EBfJkY7EALq1f/PUgrbYz4ER2eFJItVkX5/IfZ1uKLdr8sXVkdqXS9CdBHtqDUdBwCOiYQq04HseDuYpZaaRmfmZl3fZxM1nAskONHGc7SllI2NFv1qKRsRsJn1DaK6AHIDc1gTs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755355492; c=relaxed/simple; bh=425T8XrFe31ZYXPIPNALEHvQC7Iv5QFDuBEBtSxDdak=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=COjsg5w6AjN3ucvK4HF9dn4LBYg6VAMnPOrmeb0fKfGy5ukxmgtS8SgbPY6vzUdJXykVyLSsVPXYDY0jMgI34+fB8DvwbcKaa5xEQEeCjWVAmf3LmYO9c0iY8n4BupttIjxW43JLFogp/V84kS5d5EMJu2mXfyvENjcbU1rQy54= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=aOFuBYsf; arc=none smtp.client-ip=198.175.65.19 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="aOFuBYsf" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1755355491; x=1786891491; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=425T8XrFe31ZYXPIPNALEHvQC7Iv5QFDuBEBtSxDdak=; b=aOFuBYsfWfJ9sVU74ThPJULTUuPA2OKz37FLBquA5LG2UJ3UwHd3SqKe 5LPx4GVZjoY4BOvfU78IV60jIRPnQMUeW3ofyQaugkdFs1J1jBnx/zOBl UlL5jcYitVia6gIFsljcMexEhEFz6JH2eWw54HBFGNlYZDHkW/bxXkJDw oL32bG9UnHSoNGhRsZUbzpgw5K3qV2zGJKMU58xfOE0VXeZsFbKlwGAOL 7F4+CgIBxyN34aP4GAxx/zFjucp1PbfqpdCWS/5gzurIkwifyJjBewyrY VsFX65QZUjUsZ3a3r1fvXAzBcWhE3NHh/xacUhkLl+idxs5r8jj25KBj7 g==; X-CSE-ConnectionGUID: m5kz/SXyQZ+L4RmObY3OFA== X-CSE-MsgGUID: YVsFLQlSQhSLgaTO9d/Pwg== X-IronPort-AV: E=McAfee;i="6800,10657,11524"; a="57508492" X-IronPort-AV: E=Sophos;i="6.17,293,1747724400"; d="scan'208";a="57508492" Received: from orviesa002.jf.intel.com ([10.64.159.142]) by orvoesa111.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Aug 2025 07:44:51 -0700 X-CSE-ConnectionGUID: GgjB0gb6QieY+FEtMWX2mw== X-CSE-MsgGUID: Q9JO8j63SmOzYdmf71upWQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.17,293,1747724400"; d="scan'208";a="198220456" Received: from abityuts-desk.ger.corp.intel.com (HELO localhost.localdomain) ([10.245.245.93]) by orviesa002-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Aug 2025 07:44:46 -0700 From: Adrian Hunter To: pbonzini@redhat.com, seanjc@google.com Cc: kvm@vger.kernel.org, rick.p.edgecombe@intel.com, kirill.shutemov@linux.intel.com, kai.huang@intel.com, reinette.chatre@intel.com, xiaoyao.li@intel.com, tony.lindgren@linux.intel.com, binbin.wu@linux.intel.com, isaku.yamahata@intel.com, linux-kernel@vger.kernel.org, yan.y.zhao@intel.com, chao.gao@intel.com, ira.weiny@intel.com Subject: [PATCH RFC 0/2] KVM: TDX: MWAIT in guest Date: Sat, 16 Aug 2025 17:44:33 +0300 Message-ID: <20250816144436.83718-1-adrian.hunter@intel.com> X-Mailer: git-send-email 2.48.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Organization: Intel Finland Oy, Registered Address: c/o Alberga Business Park, 6 krs, Bertel Jungin Aukio 5, 02600 Espoo, Business Identity Code: 0357606 - 4, Domiciled in Helsinki Content-Transfer-Encoding: 8bit Hi TDX support for using the MWAIT instruction in a guest has issues. One option is just to disable it, see patch 1. Then perhaps provide a distinct way to enable it, documenting the limitations TDX has compared with VMX in this regard, so that users will be made aware of the limitations. See patch 2. Other options: 1. Do nothing but document the limitations. 2. Patch 1 but not patch 2; look for a better solution Adrian Hunter (2): KVM: TDX: Disable general support for MWAIT in guest KVM: TDX: Add flag to support MWAIT instruction only Documentation/virt/kvm/x86/intel-tdx.rst | 28 ++++++++++- arch/x86/include/asm/kvm_host.h | 2 + arch/x86/include/uapi/asm/kvm.h | 3 ++ arch/x86/kvm/vmx/tdx.c | 80 +++++++++++++++++++++++++------- arch/x86/kvm/x86.c | 8 ++-- 5 files changed, 98 insertions(+), 23 deletions(-) Regards Adrian