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Fri, 30 Jun 2023 12:05:16 -0700 (PDT) Received: from localhost ([192.55.54.50]) by smtp.gmail.com with ESMTPSA id t4-20020a1709028c8400b001b83db0bcf2sm4651034plo.141.2023.06.30.12.05.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 30 Jun 2023 12:05:15 -0700 (PDT) Date: Fri, 30 Jun 2023 12:05:14 -0700 From: Isaku Yamahata To: Peter Zijlstra Cc: "Huang, Kai" , "kvm@vger.kernel.org" , "Raj, Ashok" , "Luck, Tony" , "david@redhat.com" , "bagasdotme@gmail.com" , "Hansen, Dave" , "ak@linux.intel.com" , "Wysocki, Rafael J" , "kirill.shutemov@linux.intel.com" , "Chatre, Reinette" , "Christopherson,, Sean" , "pbonzini@redhat.com" , "mingo@redhat.com" , "tglx@linutronix.de" , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , "Yamahata, Isaku" , "nik.borisov@suse.com" , "hpa@zytor.com" , "Shahar, Sagi" , "imammedo@redhat.com" , "bp@alien8.de" , "Gao, Chao" , "Brown, Len" , "sathyanarayanan.kuppuswamy@linux.intel.com" , "Huang, Ying" , "Williams, Dan J" , "x86@kernel.org" , isaku.yamahata@gmail.com Subject: Re: [PATCH v12 07/22] x86/virt/tdx: Add skeleton to enable TDX on demand Message-ID: <20230630190514.GH3436214@ls.amr.corp.intel.com> References: <104d324cd68b12e14722ee5d85a660cccccd8892.1687784645.git.kai.huang@intel.com> <20230628131717.GE2438817@hirez.programming.kicks-ass.net> <0c9639db604a0670eeae5343d456e43d06b35d39.camel@intel.com> <20230630092615.GD2533791@hirez.programming.kicks-ass.net> <2659d6eef84f008635ba300f4712501ac88cef2c.camel@intel.com> <20230630183020.GA4253@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20230630183020.GA4253@hirez.programming.kicks-ass.net> X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 36DC418000A X-Stat-Signature: j14hf8cts3w53phf7kh9hb6qz819tz1k X-HE-Tag: 1688151917-571360 X-HE-Meta: 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 IXY87U6g 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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 Fri, Jun 30, 2023 at 08:30:20PM +0200, Peter Zijlstra wrote: > On Fri, Jun 30, 2023 at 09:55:32AM +0000, Huang, Kai wrote: > > On Fri, 2023-06-30 at 11:26 +0200, Peter Zijlstra wrote: > > > On Thu, Jun 29, 2023 at 12:10:00AM +0000, Huang, Kai wrote: > > > > On Wed, 2023-06-28 at 15:17 +0200, Peter Zijlstra wrote: > > > > > On Tue, Jun 27, 2023 at 02:12:37AM +1200, Kai Huang wrote: > > > > > > +EXPORT_SYMBOL_GPL(tdx_cpu_enable); > > > > > > > > > > I can't find a single caller of this.. why is this exported? > > > > > > > > It's for KVM TDX patch to use, which isn't in this series. > > > > > > > > I'll remove the export. KVM TDX series can export it. > > > > > > Fair enough; where will the KVM TDX series call this? Earlier there was > > > talk about doing it at kvm module load time -- but I objected (and still > > > do object) to that. > > > > > > What's the current plan? > > > > > > > The direction is still doing it during module load (not my series anyway). But > > this can be a separate discussion with KVM maintainers involved. > > They all on Cc afaict. > > > I understand you have concern that you don't want to have the memory & cpu time > > wasted on enabling TDX by default. For that we can have a kernel command line > > to disable TDX once for all (we can even make it default). > > That's insane, I don't want to totally disable it. I want it done at > guard creation. Do the whole TDX setup the moment you actually create a > TDX guast. > > Totally killing TDX is stupid, just about as stupid as doing it on > module load (which equates to always doing it). > > > Also, KVM will have a module parameter 'enable_tdx'. I am hoping this could > > reduce your concern too. > > I don't get this obsession with doing at module load time :/ The KVM maintainers prefer the initialization on kvm_intel.ko loading time. [1] I can change enable_tdx parameter for kvm_intel.ko instead of boolean. Something like enable_tdx ondemand: on-demand initialization when creating the first TDX guest onload: initialize TDX module when loading kvm_intel.ko disable: disable TDX support [1] https://lore.kernel.org/lkml/YkTvw5OXTTFf7j4y@google.com/ -- Isaku Yamahata