From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.18]) (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 D00534C9D; Thu, 13 Mar 2025 03:17:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741835852; cv=none; b=geEJJdeA4npu0nYqdUDVqyuQnKM3cRk6C/2bR3fsLvq2HWS70RuLHmvzv9fJYU+4QEgYmWYHr8jrFjZ+Ir0AJB3uk7Dn64U60S+pZc92Uj+IDyPa3bA0tDyHNdY68/WgJ93so4DXFA0RDSUIEsjUbSXX6kmZtljqg5ngI4DFB48= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741835852; c=relaxed/simple; bh=OekOGraYs0om9dmnsshqjY3GsKEuJkwsR5qh+YYbmLY=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=k+FSNnHMFY5ociIFa6fKy7V9W4ynEHKZ9lq+VWrWBNJ/+sh6wQ1h6jGKdNwr1w576gNk7DEMsyPZO10Kd8kO+yf85k7QOIgyw7Bs1VKLizEZnrWfwaZBHDUS/DWLT0rq2uVbp9pkM9YR/ltrhrfoM4fVZ2srVPNxstOej8coDaE= 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=RTvPH7Cw; arc=none smtp.client-ip=192.198.163.18 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="RTvPH7Cw" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1741835851; x=1773371851; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=OekOGraYs0om9dmnsshqjY3GsKEuJkwsR5qh+YYbmLY=; b=RTvPH7Cwa+rNuxVfXkSp5GNa9ZwdyqNhFG4xJg10bXkF/fwn65fr1t8g fbuSEZNREfP+vqVqb5ZDv3CeRBhyc5UlU6aNwA+gPY91986ZiWcMa8JV6 jzZ3U8/U8mfjjGZlio5TqaIZ7y8jU4i78byQHIZofwc2iE/IgC9E1ppME TJeBpyWDX0HfU1qkUxQHxYuMg2YZagmZnQv9xRQiFqXnRH9ma3N2fsWZH LbIW/AzQNNYAidu3lbgiRfkQgzVY3P+Cp8LTZpQcxPCcWPlyAFOudSxdB H+NEqFkqIX6H9RSIMfQXIi0GzteqcCmgxa3Qxl0AGPbqJr8uUK5iwAtuB w==; X-CSE-ConnectionGUID: v7P7r4mPSWyJq0wInVxiIQ== X-CSE-MsgGUID: 2JQUSwunRhejJ0+wQuGNrQ== X-IronPort-AV: E=McAfee;i="6700,10204,11371"; a="42191047" X-IronPort-AV: E=Sophos;i="6.14,243,1736841600"; d="scan'208";a="42191047" Received: from fmviesa004.fm.intel.com ([10.60.135.144]) by fmvoesa112.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Mar 2025 20:17:30 -0700 X-CSE-ConnectionGUID: rCQUFmT8S9qU0Aa5lpreBw== X-CSE-MsgGUID: jQv7TTHYTS6Ff69EiBx4kg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.14,243,1736841600"; d="scan'208";a="125899547" Received: from xiaoyaol-hp-g830.ccr.corp.intel.com (HELO [10.124.247.1]) ([10.124.247.1]) by fmviesa004-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Mar 2025 20:17:28 -0700 Message-ID: <91208627-74a6-4d19-9eef-cc8da7b0a4dc@intel.com> Date: Thu, 13 Mar 2025 11:17:26 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 05/10] KVM: TDX: restore host xsave state when exit from the guest TD To: Paolo Bonzini Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, adrian.hunter@intel.com, seanjc@google.com, rick.p.edgecombe@intel.com, Isaku Yamahata References: <20250307212053.2948340-1-pbonzini@redhat.com> <20250307212053.2948340-6-pbonzini@redhat.com> <405c30e9-73be-4812-86dc-6791b08ba43c@intel.com> Content-Language: en-US From: Xiaoyao Li In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 3/12/2025 7:36 PM, Paolo Bonzini wrote: > On Mon, Mar 10, 2025 at 8:24 AM Xiaoyao Li wrote: >> >> On 3/8/2025 5:20 AM, Paolo Bonzini wrote: >>> From: Isaku Yamahata >>> >>> On exiting from the guest TD, xsave state is clobbered; restore it. >> >> I prefer the implementation as this patch, which is straightforward. >> (I would be much better if the changelog can describe more) > > Ok: > > Do not use kvm_load_host_xsave_state(), as it relies on vcpu->arch > to find out whether other KVM_RUN code has loaded guest state into > XCR0/PKRU/XSS or not. In the case of TDX, the exit values are known > independent of the guest CR0 and CR4, and in fact the latter are not > available. In fact, I expected some description of how xsave state is clobbered and what value of them after TD exit. After return from TDH.VP.ENTER, XCR0 is set to TD's user-mode feature bits of XFAM and MSR_IA32_XSS is set to TD's supervisor-mode feature bits of XFAM. PKRU keeps unchanged if the TD is not exposed with PKU in XFAM or PKRU is set to 0 when XFAM.PKE(bit 9) is 1. If the changelog has the description of TDX module, it indeed can help people understand the code. > Thanks! > > Paolo >