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Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.96 #2 (Red Hat Linux)) id 1qEUqK-005eHM-1L; Wed, 28 Jun 2023 13:04:20 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id ABB583002F0; Wed, 28 Jun 2023 15:04:19 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 9C42C27F62BA3; Wed, 28 Jun 2023 15:04:19 +0200 (CEST) Date: Wed, 28 Jun 2023 15:04:19 +0200 From: Peter Zijlstra To: Kai Huang Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org, dave.hansen@intel.com, kirill.shutemov@linux.intel.com, tony.luck@intel.com, tglx@linutronix.de, bp@alien8.de, mingo@redhat.com, hpa@zytor.com, seanjc@google.com, pbonzini@redhat.com, david@redhat.com, dan.j.williams@intel.com, rafael.j.wysocki@intel.com, ashok.raj@intel.com, reinette.chatre@intel.com, len.brown@intel.com, ak@linux.intel.com, isaku.yamahata@intel.com, ying.huang@intel.com, chao.gao@intel.com, sathyanarayanan.kuppuswamy@linux.intel.com, nik.borisov@suse.com, bagasdotme@gmail.com, sagis@google.com, imammedo@redhat.com Subject: Re: [PATCH v12 07/22] x86/virt/tdx: Add skeleton to enable TDX on demand Message-ID: <20230628130419.GC2438817@hirez.programming.kicks-ass.net> References: <104d324cd68b12e14722ee5d85a660cccccd8892.1687784645.git.kai.huang@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <104d324cd68b12e14722ee5d85a660cccccd8892.1687784645.git.kai.huang@intel.com> X-Rspamd-Queue-Id: 946A880011 X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: p36f6g8a6gmnw8pfzpwx5nep34qfy5nx X-HE-Tag: 1687957470-334311 X-HE-Meta: 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 Il5FM2jM Uq/+BgYqFGa0RI28Llxhc6417H+xnkjcKgb9kQpS5CYkGGOeYlG0XxmTa/41qSZ9IH9ceHm0XNvkijwLSPjaIa5X44TSirr7AYMYhUQ+HR1Pl282W+QBW/QMB2G0ofdzxUolbKf6NxuRD53A= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000080, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Jun 27, 2023 at 02:12:37AM +1200, Kai Huang wrote: > +static int try_init_module_global(void) > +{ > + unsigned long flags; > + int ret; > + > + /* > + * The TDX module global initialization only needs to be done > + * once on any cpu. > + */ > + raw_spin_lock_irqsave(&tdx_global_init_lock, flags); > + > + if (tdx_global_initialized) { > + ret = 0; > + goto out; > + } > + > + /* All '0's are just unused parameters. */ > + ret = seamcall(TDH_SYS_INIT, 0, 0, 0, 0, NULL, NULL); > + if (!ret) > + tdx_global_initialized = true; > +out: > + raw_spin_unlock_irqrestore(&tdx_global_init_lock, flags); > + > + return ret; > +} How long does that TDX_SYS_INIT take and why is a raw_spinlock with IRQs disabled the right way to serialize this?