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Mon, 13 Mar 2023 21:02:01 -0700 (PDT) Date: Mon, 13 Mar 2023 21:02:00 -0700 From: Isaku Yamahata To: "Huang, Kai" Cc: "isaku.yamahata@gmail.com" , "kvm@vger.kernel.org" , "Hansen, Dave" , "david@redhat.com" , "bagasdotme@gmail.com" , "ak@linux.intel.com" , "Wysocki, Rafael J" , "linux-kernel@vger.kernel.org" , "Chatre, Reinette" , "Christopherson,, Sean" , "pbonzini@redhat.com" , "tglx@linutronix.de" , "Yamahata, Isaku" , "kirill.shutemov@linux.intel.com" , "linux-mm@kvack.org" , "Luck, Tony" , "peterz@infradead.org" , "Shahar, Sagi" , "imammedo@redhat.com" , "Gao, Chao" , "Brown, Len" , "sathyanarayanan.kuppuswamy@linux.intel.com" , "Huang, Ying" , "Williams, Dan J" Subject: Re: [PATCH v10 05/16] x86/virt/tdx: Add skeleton to enable TDX on demand Message-ID: <20230314040200.GD3922605@ls.amr.corp.intel.com> References: <20230308222738.GA3419702@ls.amr.corp.intel.com> <96b56c5b8a5876aaf6d5ccbb81bab334b10983eb.camel@intel.com> <20230313234916.GC3922605@ls.amr.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 99D024000F X-Rspam-User: X-Stat-Signature: ph5ksyassdjo4qzgb348jfnrgd4cy39q X-HE-Tag: 1678766524-634287 X-HE-Meta: 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 vKELF5ZM 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 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 Tue, Mar 14, 2023 at 01:50:40AM +0000, "Huang, Kai" wrote: > On Mon, 2023-03-13 at 16:49 -0700, Isaku Yamahata wrote: > > On Sun, Mar 12, 2023 at 11:08:44PM +0000, > > "Huang, Kai" wrote: > > > > > On Wed, 2023-03-08 at 14:27 -0800, Isaku Yamahata wrote: > > > > > + > > > > > +static int try_init_module_global(void) > > > > > +{ > > > > > + int ret; > > > > > + > > > > > + /* > > > > > + * The TDX module global initialization only needs to be done > > > > > + * once on any cpu. > > > > > + */ > > > > > + spin_lock(&tdx_global_init_lock); > > > > > + > > > > > + if (tdx_global_init_status & TDX_GLOBAL_INIT_DONE) { > > > > > + ret = tdx_global_init_status & TDX_GLOBAL_INIT_FAILED ? > > > > > + -EINVAL : 0; > > > > > + goto out; > > > > > + } > > > > > + > > > > > + /* All '0's are just unused parameters. */ > > > > > + ret = seamcall(TDH_SYS_INIT, 0, 0, 0, 0, NULL, NULL); > > > > > + > > > > > + tdx_global_init_status = TDX_GLOBAL_INIT_DONE; > > > > > + if (ret) > > > > > + tdx_global_init_status |= TDX_GLOBAL_INIT_FAILED; > > > > > > > > If entropy is lacking (rdrand failure), TDH_SYS_INIT can return TDX_SYS_BUSY. > > > > In such case, we should allow the caller to retry or make this function retry > > > > instead of marking error stickily. > > > > > > The spec says: > > > > > > TDX_SYS_BUSY The operation was invoked when another TDX module > > > operation was in progress. The operation may be retried. > > > > > > So I don't see how entropy is lacking is related to this error. Perhaps you > > > were mixing up with KEY.CONFIG? > > > > TDH.SYS.INIT() initializes global canary value. TDX module is compiled with > > strong stack protector enabled by clang and canary value needs to be > > initialized. By default, the canary value is stored at > > %fsbase: > > > > Although this is a job for libc or language runtime, TDX modules has to do it > > itself because it's stand alone. > > > > From tdh_sys_init.c > > _STATIC_INLINE_ api_error_type tdx_init_stack_canary(void) > > { > > ia32_rflags_t rflags = {.raw = 0}; > > uint64_t canary; > > if (!ia32_rdrand(&rflags, &canary)) > > { > > return TDX_SYS_BUSY; > > } > > ... > > last_page_ptr->stack_canary.canary = canary; > > > > > > Then it is a hidden behaviour of the TDX module that is not reflected in the > spec. I am not sure whether we should handle because:  > > 1) This is an extremely rare case. Kernel would be basically under attack if > such error happened. In the current series we don't handle such case in > KEY.CONFIG either but just leave a comment (see patch 13). > > 2) Not sure whether this will be changed in the future. > > So I think we should keep as is. TDX 1.5 spec introduced TDX_RND_NO_ENTROPY status code. For TDX 1.0, let's postpone it to TDX 1.5 activity. -- Isaku Yamahata