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20 Nov 2022 19:51:32 -0800 X-IronPort-AV: E=McAfee;i="6500,9779,10537"; a="765820331" X-IronPort-AV: E=Sophos;i="5.96,180,1665471600"; d="scan'208";a="765820331" Received: from mjcardon-mobl.amr.corp.intel.com (HELO [10.209.57.10]) ([10.209.57.10]) by orsmga004-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Nov 2022 19:51:31 -0800 Message-ID: <62c67ed3-e4d1-082f-800a-b0837c9432a9@linux.intel.com> Date: Sun, 20 Nov 2022 19:51:31 -0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Firefox/102.0 Thunderbird/102.2.2 Subject: Re: [PATCH v7 03/20] x86/virt/tdx: Disable TDX if X2APIC is not enabled Content-Language: en-US To: Kai Huang , linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: linux-mm@kvack.org, seanjc@google.com, pbonzini@redhat.com, dave.hansen@intel.com, dan.j.williams@intel.com, rafael.j.wysocki@intel.com, kirill.shutemov@linux.intel.com, ying.huang@intel.com, reinette.chatre@intel.com, len.brown@intel.com, tony.luck@intel.com, peterz@infradead.org, ak@linux.intel.com, isaku.yamahata@intel.com, chao.gao@intel.com, bagasdotme@gmail.com, sagis@google.com, imammedo@redhat.com References: From: Sathyanarayanan Kuppuswamy In-Reply-To: Content-Type: text/plain; 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bh=blIArHVSVsklFAOGfYFH7ACx9RuOh3kNIWTKM3T4MVU=; b=XgmouScB3WcAInw/gFpKx75tLQ4OoRu32EpGXyiJy2hT2kWkHLl3k0pxL4DXjjHZAIx5Fl uEKNbBkrnE4+dzYCix5du6uvF9gMxNAkzvK5sO8/NUe1XD1n2/7JNIEv+k0nP1RPY2Yt8E DGhwoWNNKqtUovLVqF+BE0wY0ppsXZ0= X-Stat-Signature: uurt665c3n5hrbfxwanpuk19ox18q9pj X-Rspamd-Queue-Id: 7C8FD20009 Authentication-Results: imf03.hostedemail.com; dkim=none ("invalid DKIM record") header.d=intel.com header.s=Intel header.b=USexHJDG; spf=none (imf03.hostedemail.com: domain of sathyanarayanan.kuppuswamy@linux.intel.com has no SPF policy when checking 134.134.136.20) smtp.mailfrom=sathyanarayanan.kuppuswamy@linux.intel.com; dmarc=fail reason="No valid SPF" header.from=intel.com (policy=none) X-Rspamd-Server: rspam04 X-Rspam-User: X-HE-Tag: 1669002693-935791 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 11/20/22 4:26 PM, Kai Huang wrote: > The MMIO/xAPIC interface has some problems, most notably the APIC LEAK "some problems" looks more generic. May be we can be specific here. Like it has security issues? > [1]. This bug allows an attacker to use the APIC MMIO interface to > extract data from the SGX enclave. > > TDX is not immune from this either. Early check X2APIC and disable TDX > if X2APIC is not enabled, and make INTEL_TDX_HOST depend on X86_X2APIC. > > [1]: https://aepicleak.com/aepicleak.pdf > > Link: https://lore.kernel.org/lkml/d6ffb489-7024-ff74-bd2f-d1e06573bb82@intel.com/ > Link: https://lore.kernel.org/lkml/ba80b303-31bf-d44a-b05d-5c0f83038798@intel.com/ > Signed-off-by: Kai Huang > --- > > v6 -> v7: > - Changed to use "Link" for the two lore links to get rid of checkpatch > warning. > > --- > arch/x86/Kconfig | 1 + > arch/x86/virt/vmx/tdx/tdx.c | 11 +++++++++++ > 2 files changed, 12 insertions(+) > > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index cced4ef3bfb2..dd333b46fafb 100644 > --- a/arch/x86/Kconfig > +++ b/arch/x86/Kconfig > @@ -1958,6 +1958,7 @@ config INTEL_TDX_HOST > depends on CPU_SUP_INTEL > depends on X86_64 > depends on KVM_INTEL > + depends on X86_X2APIC > help > Intel Trust Domain Extensions (TDX) protects guest VMs from malicious > host and certain physical attacks. This option enables necessary TDX > diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c > index 982d9c453b6b..8d943bdc8335 100644 > --- a/arch/x86/virt/vmx/tdx/tdx.c > +++ b/arch/x86/virt/vmx/tdx/tdx.c > @@ -12,6 +12,7 @@ > #include > #include > #include > +#include > #include > #include "tdx.h" > > @@ -81,6 +82,16 @@ static int __init tdx_init(void) > goto no_tdx; > } > > + /* > + * TDX requires X2APIC being enabled to prevent potential data > + * leak via APIC MMIO registers. Just disable TDX if not using > + * X2APIC. Remove the double space. > + */ > + if (!x2apic_enabled()) { > + pr_info("Disable TDX as X2APIC is not enabled.\n"); pr_warn()? > + goto no_tdx; > + } > + > return 0; > no_tdx: > clear_tdx(); -- Sathyanarayanan Kuppuswamy Linux Kernel Developer