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[185.218.66.243]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-48de7773d02sm4224045f8f.13.2026.10.13.23.32.06 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 13 Oct 2026 23:32:07 -0700 (PDT) Message-ID: <2b73666e-d923-4042-b719-b9bdeca783c8@suse.com> Date: Wed, 14 Oct 2026 09:32:06 +0300 Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 06/15] virt: tdx-guest: Support TDI bind and unbind operations To: "Duan, Zhenzhong" , "x86@kernel.org" , "linux-coco@lists.linux.dev" , "linux-kernel@vger.kernel.org" Cc: "dave.hansen@linux.intel.com" , "tglx@kernel.org" , "mingo@redhat.com" , "bp@alien8.de" , "hpa@zytor.com" , "Hansen, Dave" , "kas@kernel.org" , "Edgecombe, Rick P" , "jgg@nvidia.com" , "nicolinc@nvidia.com" , "aik@amd.com" , "aneesh.kumar@kernel.org" , "seanjc@google.com" , "pbonzini@redhat.com" , "yilun.xu@linux.intel.com" , "Gao, Chao" , "Verma, Vishal L" , "Li, Xiaoyao" , "Tian, Kevin" , "Peng, Chao P" References: <20260924041032.1096569-1-zhenzhong.duan@intel.com> <20260924041032.1096569-7-zhenzhong.duan@intel.com> <00a4b474-eb13-4caa-90c6-b9cabb1ec621@suse.com> From: Nikolay Borisov Content-Language: en-US Autocrypt: addr=nik.borisov@suse.com; keydata= xsFNBGcrpvIBEAD5cAR5+qu30GnmPrK9veWX5RVzzbgtkk9C/EESHy9Yz0+HWgCVRoNyRQsZ 7DW7vE1KhioDLXjDmeu8/0A8u5nFMqv6d1Gt1lb7XzSAYw7uSWXLPEjFBtz9+fBJJLgbYU7G OpTKy6gRr6GaItZze+r04PGWjeyVUuHZuncTO7B2huxcwIk9tFtRX21gVSOOC96HcxSVVA7X N/LLM2EOL7kg4/yDWEhAdLQDChswhmdpHkp5g6ytj9TM8bNlq9I41hl/3cBEeAkxtb/eS5YR 88LBb/2FkcGnhxkGJPNB+4Siku7K8Mk2Y6elnkOctJcDvk29DajYbQnnW4nhfelZuLNupb1O M0912EvzOVI0dIVgR+xtosp66bYTOpX4Xb0fylED9kYGiuEAeoQZaDQ2eICDcHPiaLzh+6cc pkVTB0sXkWHUsPamtPum6/PgWLE9vGI5s+FaqBaqBYDKyvtJfLK4BdZng0Uc3ijycPs3bpbQ bOnK9LD8TYmYaeTenoNILQ7Ut54CCEXkP446skUMKrEo/HabvkykyWqWiIE/UlAYAx9+Ckho TT1d2QsmsAiYYWwjU8igXBecIbC0uRtF/cTfelNGrQwbICUT6kJjcOTpQDaVyIgRSlUMrlNZ XPVEQ6Zq3/aENA8ObhFxE5PLJPizJH6SC89BMKF3zg6SKx0qzQARAQABzSZOaWtvbGF5IEJv cmlzb3YgPG5pay5ib3Jpc292QHN1c2UuY29tPsLBkQQTAQoAOxYhBDuWB8EJLBUZCPjT3SRn XZEnyhfsBQJnK6byAhsDBQsJCAcCAiICBhUKCQgLAgQWAgMBAh4HAheAAAoJECRnXZEnyhfs XbIQAJxuUnelGdXbSbtovBNm+HF3LtT0XnZ0+DoR0DemUGuA1bZAlaOXGr5mvVbTgaoGUQIJ 3Ejx3UBEG7ZSJcfJobB34w1qHEDO0pN9orGIFT9Bic3lqhawD2r85QMcWwjsZH5FhyRx7P2o DTuUClLMO95GuHYQngBF2rHHl8QMJPVKsR18w4IWAhALpEApxa3luyV7pAAqKllfCNt7tmed uKmclf/Sz6qoP75CvEtRbfAOqYgG1Uk9A62C51iAPe35neMre3WGLsdgyMj4/15jPYi+tOUX Tc7AAWgc95LXyPJo8069MOU73htZmgH4OYy+S7f+ArXD7h8lTLT1niff2bCPi6eiAQq6b5CJ Ka4/27IiZo8tm1XjLYmoBmaCovqx5y5Xt2koibIWG3ZGD2I+qRwZ0UohKRH6kKVHGcrmCv0J YO8yIprxgoYmA7gq21BpTqw3D4+8xujn/6LgndLKmGESM1FuY3ymXgj5983eqaxicKpT9iq8 /a1j31tms4azR7+6Dt8H4SagfN6VbJ0luPzobrrNFxUgpjR4ZyQQ++G7oSRdwjfIh1wuCF6/ mDUNcb6/kA0JS9otiC3omfht47yQnvod+MxFk1lTNUu3hePJUwg1vT1te3vO5oln8lkUo9BU knlYpQ7QA2rDEKs+YWqUstr4pDtHzwQ6mo0rqP+zzsFNBGcrpvIBEADGYTFkNVttZkt6e7yA LNkv3Q39zQCt8qe7qkPdlj3CqygVXfw+h7GlcT9fuc4kd7YxFys4/Wd9icj9ZatGMwffONmi LnUotIq2N7+xvc4Xu76wv+QJpiuGEfCDB+VdZOmOzUPlmMkcJc/EDSH4qGogIYRu72uweKEq VfBI43PZIGpGJ7TjS3THX5WVI2YNSmuwqxnQF/iVqDtD2N72ObkBwIf9GnrOgxEyJ/SQq2R0 g7hd6IYk7SOKt1a8ZGCN6hXXKzmM6gHRC8fyWeTqJcK4BKSdX8PzEuYmAJjSfx4w6DoxdK5/ 9sVrNzaVgDHS0ThH/5kNkZ65KNR7K2nk45LT5Crjbg7w5/kKDY6/XiXDx7v/BOR/a+Ryo+lM MffN3XSnAex8cmIhNINl5Z8CAvDLUtItLcbDOv7hdXt6DSyb65CdyY8JwOt6CWno1tdjyDEG 5ANwVPYY878IFkOJLRTJuUd5ltybaSWjKIwjYJfIXuoyzE7OL63856MC/Os8PcLfY7vYY2LB cvKH1qOcs+an86DWX17+dkcKD/YLrpzwvRMur5+kTgVfXcC0TAl39N4YtaCKM/3ugAaVS1Mw MrbyGnGqVMqlCpjnpYREzapSk8XxbO2kYRsZQd8J9ei98OSqgPf8xM7NCULd/xaZLJUydql1 JdSREId2C15jut21aQARAQABwsF2BBgBCgAgFiEEO5YHwQksFRkI+NPdJGddkSfKF+wFAmcr pvICGwwACgkQJGddkSfKF+xuuxAA4F9iQc61wvAOAidktv4Rztn4QKy8TAyGN3M8zYf/A5Zx VcGgX4J4MhRUoPQNrzmVlrrtE2KILHxQZx5eQyPgixPXri42oG5ePEXZoLU5GFRYSPjjTYmP ypyTPN7uoWLfw4TxJqWCGRLsjnkwvyN3R4161Dty4Uhzqp1IkNhl3ifTDYEvbnmHaNvlvvna 7+9jjEBDEFYDMuO/CA8UtoVQXjy5gtOhZZkEsptfwQYc+E9U99yxGofDul7xH41VdXGpIhUj 4wjd3IbgaCiHxxj/M9eM99ybu5asvHyMo3EFPkyWxZsBlUN/riFXGspG4sT0cwOUhG2ZnExv XXhOGKs/y3VGhjZeCDWZ+0ZQHPCL3HUebLxW49wwLxvXU6sLNfYnTJxdqn58Aq4sBXW5Un0Q vfbd9VFV/bKFfvUscYk2UKPi9vgn1hY38IfmsnoS8b0uwDq75IBvup9pYFyNyPf5SutxhFfP JDjakbdjBoYDWVoaPbp5KAQ2VQRiR54lir/inyqGX+dwzPX/F4OHfB5RTiAFLJliCxniKFsM d8eHe88jWjm6/ilx4IlLl9/MdVUGjLpBi18X7ejLz3U2quYD8DBAGzCjy49wJ4Di4qQjblb2 pTXoEyM2L6E604NbDu0VDvHg7EXh1WwmijEu28c/hEB6DwtzslLpBSsJV0s1/jE= In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 14.10.26 г. 6:06 ч., Duan, Zhenzhong wrote: > > >> -----Original Message----- >> From: Nikolay Borisov >> Subject: Re: [RFC PATCH 06/15] virt: tdx-guest: Support TDI bind and unbind >> operations >> >> >> >> On 24.09.26 г. 7:10 ч., Zhenzhong Duan wrote: >>> Introduce support for binding and unbinding the Trust Device Interface >>> (TDI) using the TDCM_OP_BIND and TDCM_OP_UNBIND commands. >>> >>> Executing TDCM_OP_BIND transitions the TDI state to a locked state >>> (TDI_STATE_CONFIG_LOCKED). Add a sanity check following the bind operation >>> to verify this state transition succeeded before finalizing device locking. >>> >>> Signed-off-by: Zhenzhong Duan >> >> >> >>> struct tdx_devsec *tdevsec __free(kfree) = kzalloc(sizeof(*tdevsec), >> GFP_KERNEL); >>> @@ -174,6 +233,19 @@ static struct pci_tsm *tdx_devsec_lock(struct tsm_dev >> *tsm_dev, struct pci_dev * >>> if (!tdx_is_dev_teeio_support(tdevsec)) >>> return ERR_PTR(-EOPNOTSUPP); >>> >>> + struct tdx_devsec *tdevsec_bind __free(tdx_tdi_unbind_dev) = >> tdx_tdi_bind_dev(tdevsec); >>> + if (IS_ERR(tdevsec_bind)) >>> + return ERR_CAST(tdevsec_bind); >>> + >>> + ret = tdx_tdi_read_state(tdevsec, &state); >>> + if (ret) >>> + return ERR_PTR(ret); >>> + >>> + if (state != TDI_STATE_CONFIG_LOCKED) >>> + return ERR_PTR(-EIO); >> >> While this does seem correct, it's not really following the spec or I'm being too >> rigid, namely: >> >> Since TDI can change the state any time, TD can't fully rely on the Known RUN >> state in any scenario. However, TD can rely on the Known >> RUN state after TDG.TDI.START as a confirmation of the Interface Start. > > About TDI changing state any time, do you mean host changes TDI state, > e.g., through TDH.TDI.STOP? Or you mean TDI device goes into TDISP error state > due to hw error? Can't they happen even after TDG.TDI.START? I've taken this verbatim from the latest TDX connect spec, I'd assume what it refers to is the TDI/device getting into error state because the DSM deemed so because of whatever reason. I believe there is an inherent TOCTOU race here, because you can at best get a momentary snapshot of the state but the DSM, which is inherently an independent entry could for whatever reason decide to enter in error state (highly unlikely, but still possible!) > >> >> But here we still haven't done a START, just a BIND, no ? > > Yes > > > I understand this as a best-effort sanity check, not a guarantee that > the interface will remain in this state. > > For example, suppose the host creates the TDI but incorrectly reports > BIND complete without completing TDH.TDI.BIND. In the module > implementation I’m looking at, TDG.TDI.RD(INTERFACE_STATE) returns the > stored TDISP state without requiring the internal TDI state to be BOUND. > A successful read could therefore return CONFIG_UNLOCKED. > > At this point we have bound the interface but have not started it, so > CONFIG_LOCKED is the state we expect. Checking it catches that > inconsistency; checking only the TDCALL return code would not. This is > still a snapshot, not proof against a subsequent state change. Makes sense, IIUC it states the same thing I stated above i.e a snapshot, so perhaps this check could be carved in a different patch with the changelog containing this reasoning? > > BRs, > Zhenzhong >