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[84.3.50.134]) by smtp.gmail.com with ESMTPSA id j5sm7271212edh.41.2020.07.27.04.07.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 27 Jul 2020 04:07:10 -0700 (PDT) Date: Mon, 27 Jul 2020 13:07:08 +0200 From: Ingo Molnar To: Ricardo Neri Cc: Thomas Gleixner , Borislav Petkov , Andy Lutomirski , x86@kernel.org, Dave Hansen , Tony Luck , Cathy Zhang , Fenghua Yu , "H. Peter Anvin" , Kyung Min Park , "Peter Zijlstra (Intel)" , "Ravi V. Shankar" , Sean Christopherson , linux-kernel@vger.kernel.org, Ricardo Neri Subject: Re: [PATCH 0/4] x86/cpu: Use SERIALIZE in sync_core() Message-ID: <20200727110708.GA3174@gmail.com> References: <20200727043132.15082-1-ricardo.neri-calderon@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200727043132.15082-1-ricardo.neri-calderon@linux.intel.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Ricardo Neri wrote: > A recent submission to LKML introduced a CPU feature flag for a new > Intel architecture Serializing Instruction, SERIALIZE [1]. Unlike the > existing Serializing Instructions, this new instruction does not have > side effects such as clobbering registers or exiting to a hypervisor. > > As stated in the Intel "extensions" (ISE) manual [2], this instruction > will appear first in Sapphire Rapids and Alder Lake. > > Andy Lutomirski suggested to use this instruction in sync_core() as it > serves the very purpose of this function [3]. > > For completeness, I picked patch #3 from Cathy's series (and has become > patch #1 here) [1]. Her series depends on such patch to build correctly. > Maybe it can be merged independently while the discussion continues? > > Thanks and BR, > Ricardo > > [1]. https://lore.kernel.org/kvm/1594088183-7187-1-git-send-email-cathy.zhang@intel.com/ > [2]. https://software.intel.com/sites/default/files/managed/c5/15/architecture-instruction-set-extensions-programming-reference.pdf > [3]. https://lore.kernel.org/kvm/CALCETrWudiF8G8r57r5i4JefuP5biG1kHg==0O8YXb-bYS-0BA@mail.gmail.com/ > > Ricardo Neri (4): > x86/cpufeatures: Add enumeration for SERIALIZE instruction > x86/cpu: Relocate sync_core() to sync_core.h > x86/cpu: Refactor sync_core() for readability > x86/cpu: Use SERIALIZE in sync_core() when available I've picked up the first 3 preparatory patches into tip:x86/cpu, as they are valid improvements even without the 4th patch. The actual functionality in the 4th patch still needs work. Thannks, Ingo