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([2a10:bac0:b000:7579:7285:c2ff:fedd:7e3a]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4229c60f758sm212680845e9.20.2024.06.18.08.12.14 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 18 Jun 2024 08:12:15 -0700 (PDT) Message-ID: <8524dec4-be7a-4423-8d02-92cc1bb4bf3c@suse.com> Date: Tue, 18 Jun 2024 18:12:13 +0300 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 9/9] x86/virt/tdx: Don't initialize module that doesn't support NO_RBP_MOD feature To: Kai Huang , linux-kernel@vger.kernel.org Cc: x86@kernel.org, dave.hansen@intel.com, dan.j.williams@intel.com, kirill.shutemov@linux.intel.com, rick.p.edgecombe@intel.com, peterz@infradead.org, tglx@linutronix.de, bp@alien8.de, mingo@redhat.com, hpa@zytor.com, seanjc@google.com, pbonzini@redhat.com, kvm@vger.kernel.org, isaku.yamahata@intel.com, binbin.wu@linux.intel.com References: <909d809d0a37e51babfe28f88c7fd1fdefa53e88.1718538552.git.kai.huang@intel.com> From: Nikolay Borisov Content-Language: en-US In-Reply-To: <909d809d0a37e51babfe28f88c7fd1fdefa53e88.1718538552.git.kai.huang@intel.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 16.06.24 г. 15:01 ч., Kai Huang wrote: > Old TDX modules can clobber RBP in the TDH.VP.ENTER SEAMCALL. However > RBP is used as frame pointer in the x86_64 calling convention, and > clobbering RBP could result in bad things like being unable to unwind > the stack if any non-maskable exceptions (NMI, #MC etc) happens in that > gap. > > A new "NO_RBP_MOD" feature was introduced to more recent TDX modules to > not clobber RBP. This feature is reported in the TDX_FEATURES0 global > metadata field via bit 18. > > Don't initialize the TDX module if this feature is not supported [1]. > > Link: https://lore.kernel.org/all/c0067319-2653-4cbd-8fee-1ccf21b1e646@suse.com/T/#mef98469c51e2382ead2c537ea189752360bd2bef [1] > Signed-off-by: Kai Huang Reviewed-by: Nikolay Borisov