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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 1qEUoz-005eGG-12; Wed, 28 Jun 2023 13:02:57 +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 E9BB73002F0; Wed, 28 Jun 2023 15:02:56 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id D1AB727F62BA0; Wed, 28 Jun 2023 15:02:56 +0200 (CEST) Date: Wed, 28 Jun 2023 15:02:56 +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 06/22] x86/virt/tdx: Handle SEAMCALL running out of entropy error Message-ID: <20230628130256.GB2438817@hirez.programming.kicks-ass.net> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: 454A01A0065 X-Rspam-User: X-Stat-Signature: kftfdp8ay8a7tkbrqn7tcmfes1embu19 X-Rspamd-Server: rspam01 X-HE-Tag: 1687957384-861116 X-HE-Meta: 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 tKVKD7Xf GPdOo/2vrzw8nQr8tW/9g8dJSNGTC3cTI1yJV/QljKYHUYqCn3+kq4NZ2VwgrOO6swWugQSoDmImxwEaYqphWsAYWJk3oY2GKPAFYJo8idF7LHrppU9liTHoBfTOX0CbvEiV+1dIEq598F4w= X-Bogosity: Ham, tests=bogofilter, spamicity=0.011700, 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 02:12:36AM +1200, Kai Huang wrote: > cpu = get_cpu(); > - sret = __seamcall(fn, rcx, rdx, r8, r9, out); > + > + /* > + * Certain SEAMCALL leaf functions may return error due to > + * running out of entropy, in which case the SEAMCALL should > + * be retried. Handle this in SEAMCALL common function. > + * > + * Mimic rdrand_long() retry behavior. Yeah, except that doesn't have preemption disabled.. you do. > + */ > + do { > + sret = __seamcall(fn, rcx, rdx, r8, r9, out); > + } while (sret == TDX_RND_NO_ENTROPY && --retry); > + > put_cpu();