From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.zytor.com (terminus.zytor.com [198.137.202.136]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7403E23F26A; Thu, 3 Apr 2025 07:14:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.136 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743664475; cv=none; b=RIzIufsVYgXIuRanLibrvbBN2E2AI+btWro1mNEcKFwPh24PTpYsg+o/8oWR80POCUObE8qNcExOof4fvmdWI7PegAxRCbHX22dGBUkGOivs9gTv7peDlPQzsPpiCrAutm6dsp8JUoGZmOTk3dxqfJA4bB0ZhdIwk+tB1+Fj0Hs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743664475; c=relaxed/simple; bh=i9chyyVVA4u/5n6H3ot6TYnyHk7hwD1gNPF2JpU27pA=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=WkU2IsrT/hmZ9X+Bd+CrarCA2ohHSGeVZ6+1vgiUctvz44RXKveLgFSEmA4GUSbN2hmRBdWraJi67fXZkJqAFqSi2GD9++vRuEvvCbv8dx30yyisz1gyG6mf6DFTSNlIEXYVGbtf44TcvWw5kwK+vPo4NYueqsAOOU+Xs8SAXi4= ARC-Authentication-Results:i=1; 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h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=LvUp7AXAlEO7ZIoS25ITyVlvXptK8gf870o88D54rWCbMQJtullUs6cSr27rMyA/c e00XhjujppWmi0xvi52Gm5YkQ9UqdP9DhcXE4mt5uG56eLAwJBxdh7bKLKbRIqR2p0 hxKa4VWv19GOJTD4k62M7VFYmdH3jsk65f7uqAnVJxOmWHStXYZEEGIcS6Niv2j2w8 IpwtqFX6o9BUdi073LOjU6OWdKPza4N1Bv/d9TXdnTnKbzJm97DWYQJKY13xLxauZ1 08EiDBm8bzmIvt+yzgcbSw7C5JTPomxa++o0v4ZpnafbOTywuWRfv+qFdLQxvDDbc8 M3z/FLprqi4PA== Message-ID: <9618fccf-3620-4395-bdac-aa8999fe2437@zytor.com> Date: Thu, 3 Apr 2025 00:13:35 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH v1 01/15] x86/msr: Replace __wrmsr() with native_wrmsrl() To: Andrew Cooper , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, linux-hyperv@vger.kernel.org, virtualization@lists.linux.dev, linux-edac@vger.kernel.org, kvm@vger.kernel.org, xen-devel@lists.xenproject.org, linux-ide@vger.kernel.org, linux-pm@vger.kernel.org, bpf@vger.kernel.org, llvm@lists.linux.dev Cc: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, jgross@suse.com, peterz@infradead.org, acme@kernel.org, namhyung@kernel.org, mark.rutland@arm.com, alexander.shishkin@linux.intel.com, jolsa@kernel.org, irogers@google.com, adrian.hunter@intel.com, kan.liang@linux.intel.com, wei.liu@kernel.org, ajay.kaher@broadcom.com, bcm-kernel-feedback-list@broadcom.com, tony.luck@intel.com, pbonzini@redhat.com, vkuznets@redhat.com, seanjc@google.com, luto@kernel.org, boris.ostrovsky@oracle.com, kys@microsoft.com, haiyangz@microsoft.com, decui@microsoft.com References: <20250331082251.3171276-1-xin@zytor.com> <20250331082251.3171276-2-xin@zytor.com> <0da43a86-81b0-4388-b47b-3a76b15f2a4c@citrix.com> Content-Language: en-US From: Xin Li Autocrypt: addr=xin@zytor.com; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 3/31/2025 2:45 PM, Andrew Cooper wrote: > On 31/03/2025 9:22 am, Xin Li (Intel) wrote: >> __wrmsr() is the lowest level primitive MSR write API, and its direct >> use is NOT preferred. Use its wrapper function native_wrmsrl() instead. >> >> No functional change intended. >> >> Signed-off-by: Xin Li (Intel) > > The critical piece of information you're missing from the commit message > is that the MSR_IMM instructions take a single u64. > > Therefore to use them, you've got to arrange for all callers to provide > a single u64, rather than a split u32 pair. You definitely caught me on how I was thinking it ;) Sometimes it is nice to see a change log with a thinking process. Thanks! Xin