From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id E9721D44D6F for ; Wed, 6 Nov 2024 13:58:13 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1t8gXi-00073l-Ud; Wed, 06 Nov 2024 08:57:54 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1t8gXb-0006zs-IS for qemu-devel@nongnu.org; Wed, 06 Nov 2024 08:57:48 -0500 Received: from mgamail.intel.com ([198.175.65.17]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1t8gXZ-0000tS-8l for qemu-devel@nongnu.org; Wed, 06 Nov 2024 08:57:47 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1730901466; x=1762437466; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=zwAC45OJhmnmO548e21DRwBu5ZsdXTpXh46ezboPAA0=; b=WGnAtiKB9WjTcdNOZ7J3Nuq1wHCQ4lr6FixZYJnLi3x/NqR7MGFidc8K DayyAOYc8jV/Sv638UgprN42uZVJbKhsxMrAkY0o9nrhGckMjxTB41aj0 zp5Aov7wYKRyZVoD2nhDz1LhcTH5t0XMF30d6tixxfxEflN57BAP5cpNu Zys08seJ9nOmBDWK7Q1lMJjUK87jJL52KyN/h72RQMaBHmhryU5q4dYNj QZuI6x1aLQCHEmJL9AdGmLxxDSmaFfHEx+DQfr5YkN8DOuqHZUF2uXwb6 cnO4PEjqe22HLMI3YzGMApCpkqGcHPLGbkAqTWufAyQ/eE7ac6dLuanam g==; X-CSE-ConnectionGUID: FBfBtSV6T5S72SAj5EUrjg== X-CSE-MsgGUID: Gf5163wSQWiN7fpV3gebXw== X-IronPort-AV: E=McAfee;i="6700,10204,11248"; a="30812702" X-IronPort-AV: E=Sophos;i="6.11,262,1725346800"; d="scan'208";a="30812702" Received: from orviesa006.jf.intel.com ([10.64.159.146]) by orvoesa109.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Nov 2024 05:57:41 -0800 X-CSE-ConnectionGUID: 9/wVuzWVSm+bO4Sl9QL7Gw== X-CSE-MsgGUID: o/0fKsyyQkKtzT+HyjzVuA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.11,262,1725346800"; d="scan'208";a="84680014" Received: from xiaoyaol-hp-g830.ccr.corp.intel.com (HELO [10.124.247.1]) ([10.124.247.1]) by orviesa006-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Nov 2024 05:57:35 -0800 Message-ID: <35233d1f-eb6c-4882-abd6-884c1f559e12@intel.com> Date: Wed, 6 Nov 2024 21:57:29 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v6 45/60] i386/tdx: Don't get/put guest state for TDX VMs To: Paolo Bonzini , Riku Voipio , Richard Henderson , Zhao Liu , "Michael S. Tsirkin" , Marcel Apfelbaum , Igor Mammedov , Ani Sinha Cc: =?UTF-8?Q?Philippe_Mathieu-Daud=C3=A9?= , Yanan Wang , Cornelia Huck , =?UTF-8?Q?Daniel_P=2E_Berrang=C3=A9?= , Eric Blake , Markus Armbruster , Marcelo Tosatti , rick.p.edgecombe@intel.com, kvm@vger.kernel.org, qemu-devel@nongnu.org References: <20241105062408.3533704-1-xiaoyao.li@intel.com> <20241105062408.3533704-46-xiaoyao.li@intel.com> <8cd78103-5f49-4cbd-814d-a03a82a59231@redhat.com> Content-Language: en-US From: Xiaoyao Li In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=198.175.65.17; envelope-from=xiaoyao.li@intel.com; helo=mgamail.intel.com X-Spam_score_int: -39 X-Spam_score: -4.0 X-Spam_bar: ---- X-Spam_report: (-4.0 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.34, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, HK_RANDOM_ENVFROM=0.001, HK_RANDOM_FROM=0.781, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 11/5/2024 10:23 PM, Paolo Bonzini wrote: > On 11/5/24 12:25, Xiaoyao Li wrote: >> On 11/5/2024 5:55 PM, Paolo Bonzini wrote: >>> On 11/5/24 07:23, Xiaoyao Li wrote: >>>> From: Sean Christopherson >>>> >>>> Don't get/put state of TDX VMs since accessing/mutating guest state of >>>> production TDs is not supported. >>>> >>>> Note, it will be allowed for a debug TD. Corresponding support will be >>>> introduced when debug TD support is implemented in the future. >>>> >>>> Signed-off-by: Sean Christopherson >>>> Signed-off-by: Xiaoyao Li >>>> Acked-by: Gerd Hoffmann >>> >>> This should be unnecessary now that QEMU has >>> kvm_mark_guest_state_protected(). >> >> Reverting this patch, we get: >> >> tdx: tdx: error: failed to set MSR 0x174 to 0x0 >> tdx: ../../../go/src/tdx/tdx-qemu/target/i386/kvm/kvm.c:3859: >> kvm_buf_set_msrs: Assertion `ret == cpu->kvm_msr_buf->nmsrs' failed. >> error: failed to set MSR 0x174 to 0x0 >> tdx: ../../../go/src/tdx/tdx-qemu/target/i386/kvm/kvm.c:3859: >> kvm_buf_set_msrs: Assertion `ret == cpu->kvm_msr_buf->nmsrs' failed. > Difficult to "debug" without even a backtrace, but you might be calling > kvm_mark_guest_state_protected() too late.  For SNP, the entry values of > the registers are customizable, for TDX they're not.  So for TDX I think > it should be called even before realize completes, whereas SNP only > calls it on the first transition to RUNNING. TDX calls kvm_mark_guest_state_protected() very early in kvm_arch_init() -> tdx_kvm_init() I find the call site. It's caused by kvm_arch_put_register() called in kvm_cpu_exec() because cpu->vcpu_dirty is set to true in kvm_create_vcpu(). Maybe we can do something like below? 8<<<<<<<<<<<<<<<<<<<<<<<<<<<< --- a/accel/kvm/kvm-all.c +++ b/accel/kvm/kvm-all.c @@ -457,7 +457,9 @@ int kvm_create_vcpu(CPUState *cpu) cpu->kvm_fd = kvm_fd; cpu->kvm_state = s; - cpu->vcpu_dirty = true; + if (!s->guest_state_protected) { + cpu->vcpu_dirty = true; + } cpu->dirty_pages = 0; cpu->throttle_us_per_full = 0; > Paolo >