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 4B5BCBA2D for ; Thu, 9 Jan 2025 18:49:09 +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=1736448552; cv=none; b=ULJDyQ7DYJgUhMM+73C1cnejzsiRX751ptlFnz3YY9bYPhIld9zpM+ZfMdNCDIAt6hvKnN7UEplgao1PxvXqiYXdUcDzr2ah24g0ln4RlSQfEKlG+jYRS8n2wvO0YSXozewvQz3tKXCkN40lX66CYceuVq7z5lgJqw+n/pBpR6I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736448552; c=relaxed/simple; bh=xc0AefGWVQyY8gZER7nv7tKd0nhrNWxLJqG5n+cmmow=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=acOWLXr4xCFFiBIP4AVaaAHmKe3FnkSvo8siXXHn7l9KdWfiLvsm+NC6hkMoOGrGWdK6GnTG9g2dsyGjudfdlHjDyyuT3GctmXYUuIsm9muIRu3zCHwkT1kv5ADKvPgkhiemKk2YFQIJM0BZruILi/PC8E2u3WcscV76JlRsMAc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zytor.com; spf=pass smtp.mailfrom=zytor.com; dkim=pass (2048-bit key) header.d=zytor.com header.i=@zytor.com header.b=QZ7BAG5F; arc=none smtp.client-ip=198.137.202.136 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zytor.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=zytor.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=zytor.com header.i=@zytor.com header.b="QZ7BAG5F" Received: from [192.168.7.202] ([71.202.166.45]) (authenticated bits=0) by mail.zytor.com (8.18.1/8.17.1) with ESMTPSA id 509ImXeY821143 (version=TLSv1.3 cipher=TLS_AES_128_GCM_SHA256 bits=128 verify=NO); Thu, 9 Jan 2025 10:48:33 -0800 DKIM-Filter: OpenDKIM Filter v2.11.0 mail.zytor.com 509ImXeY821143 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zytor.com; s=2024121701; t=1736448514; bh=7GS3NsVSUz4NGg7lfmQi4O+KIzfkHSwF+nPBtbF/ItI=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=QZ7BAG5FzeC22pPLxgUAbWxNY9Ph/D37e0clJDW9wXz0ML0y+t0Oqe8gHYqjHq32B E5FgG2rFmKw5syxBY4AsDbs+e08+UizJNPkCXcVLuWI+f1w6n8fSKsumTayP8w8xti GqBIe8Zf3StmsMfFd++loAigt2DveWppQ3DpH5BwFRt2pM924pIPfkw+i6llYjV7k2 zayh+b87rTQ7SZlD5/bnV5mt+KOqXT7umF2cnVFVWBGC6n/QHk1S048T3RgCXe49GP 2u5FR3k4faXgdrlTFMKVWWh2q7hcjNJqkKkYNQM0edegxvS9iNEP0o4OABI+TUPLoc eh9LFShsfquiw== Message-ID: Date: Thu, 9 Jan 2025 10:48:32 -0800 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: [PATCH v1 1/1] x86/fred: Fix the FRED RSP0 MSR out of sync with its per CPU cache To: "H. Peter Anvin" , Dave Hansen , linux-kernel@vger.kernel.org Cc: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, andrew.cooper3@citrix.com References: <20250108023641.17396-1-xin@zytor.com> <1D01F3E8-BEFF-4938-B538-C3657AA31742@zytor.com> Content-Language: en-US From: Xin Li Autocrypt: addr=xin@zytor.com; keydata= xsDNBGUPz1cBDACS/9yOJGojBFPxFt0OfTWuMl0uSgpwk37uRrFPTTLw4BaxhlFL0bjs6q+0 2OfG34R+a0ZCuj5c9vggUMoOLdDyA7yPVAJU0OX6lqpg6z/kyQg3t4jvajG6aCgwSDx5Kzg5 Rj3AXl8k2wb0jdqRB4RvaOPFiHNGgXCs5Pkux/qr0laeFIpzMKMootGa4kfURgPhRzUaM1vy bsMsL8vpJtGUmitrSqe5dVNBH00whLtPFM7IbzKURPUOkRRiusFAsw0a1ztCgoFczq6VfAVu raTye0L/VXwZd+aGi401V2tLsAHxxckRi9p3mc0jExPc60joK+aZPy6amwSCy5kAJ/AboYtY VmKIGKx1yx8POy6m+1lZ8C0q9b8eJ8kWPAR78PgT37FQWKYS1uAroG2wLdK7FiIEpPhCD+zH wlslo2ETbdKjrLIPNehQCOWrT32k8vFNEMLP5G/mmjfNj5sEf3IOKgMTMVl9AFjsINLHcxEQ 6T8nGbX/n3msP6A36FDfdSEAEQEAAc0WWGluIExpIDx4aW5Aenl0b3IuY29tPsLBDQQTAQgA NxYhBIUq/WFSDTiOvUIqv2u9DlcdrjdRBQJlD89XBQkFo5qAAhsDBAsJCAcFFQgJCgsFFgID AQAACgkQa70OVx2uN1HUpgv/cM2fsFCQodLArMTX5nt9yqAWgA5t1srri6EgS8W3F+3Kitge tYTBKu6j5BXuXaX3vyfCm+zajDJN77JHuYnpcKKr13VcZi1Swv6Jx1u0II8DOmoDYLb1Q2ZW v83W55fOWJ2g72x/UjVJBQ0sVjAngazU3ckc0TeNQlkcpSVGa/qBIHLfZraWtdrNAQT4A1fa sWGuJrChBFhtKbYXbUCu9AoYmmbQnsx2EWoJy3h7OjtfFapJbPZql+no5AJ3Mk9eE5oWyLH+ QWqtOeJM7kKvn/dBudokFSNhDUw06e7EoVPSJyUIMbYtUO7g2+Atu44G/EPP0yV0J4lRO6EA wYRXff7+I1jIWEHpj5EFVYO6SmBg7zF2illHEW31JAPtdDLDHYcZDfS41caEKOQIPsdzQkaQ oW2hchcjcMPAfyhhRzUpVHLPxLCetP8vrVhTvnaZUo0xaVYb3+wjP+D5j/3+hwblu2agPsaE vgVbZ8Fx3TUxUPCAdr/p73DGg57oHjgezsDNBGUPz1gBDAD4Mg7hMFRQqlzotcNSxatlAQNL MadLfUTFz8wUUa21LPLrHBkUwm8RujehJrzcVbPYwPXIO0uyL/F///CogMNx7Iwo6by43KOy g89wVFhyy237EY76j1lVfLzcMYmjBoTH95fJC/lVb5Whxil6KjSN/R/y3jfG1dPXfwAuZ/4N cMoOslWkfZKJeEut5aZTRepKKF54T5r49H9F7OFLyxrC/uI9UDttWqMxcWyCkHh0v1Di8176 jjYRNTrGEfYfGxSp+3jYL3PoNceIMkqM9haXjjGl0W1B4BidK1LVYBNov0rTEzyr0a1riUrp Qk+6z/LHxCM9lFFXnqH7KWeToTOPQebD2B/Ah5CZlft41i8L6LOF/LCuDBuYlu/fI2nuCc8d m4wwtkou1Y/kIwbEsE/6RQwRXUZhzO6llfoN96Fczr/RwvPIK5SVMixqWq4QGFAyK0m/1ap4 bhIRrdCLVQcgU4glo17vqfEaRcTW5SgX+pGs4KIPPBE5J/ABD6pBnUUAEQEAAcLA/AQYAQgA JhYhBIUq/WFSDTiOvUIqv2u9DlcdrjdRBQJlD89ZBQkFo5qAAhsMAAoJEGu9DlcdrjdR4C0L /RcjolEjoZW8VsyxWtXazQPnaRvzZ4vhmGOsCPr2BPtMlSwDzTlri8BBG1/3t/DNK4JLuwEj OAIE3fkkm+UG4Kjud6aNeraDI52DRVCSx6xff3bjmJsJJMb12mWglN6LjdF6K+PE+OTJUh2F dOhslN5C2kgl0dvUuevwMgQF3IljLmi/6APKYJHjkJpu1E6luZec/lRbetHuNFtbh3xgFIJx 2RpgVDP4xB3f8r0I+y6ua+p7fgOjDLyoFjubRGed0Be45JJQEn7A3CSb6Xu7NYobnxfkwAGZ Q81a2XtvNS7Aj6NWVoOQB5KbM4yosO5+Me1V1SkX2jlnn26JPEvbV3KRFcwV5RnDxm4OQTSk PYbAkjBbm+tuJ/Sm+5Yp5T/BnKz21FoCS8uvTiziHj2H7Cuekn6F8EYhegONm+RVg3vikOpn gao85i4HwQTK9/D1wgJIQkdwWXVMZ6q/OALaBp82vQ2U9sjTyFXgDjglgh00VRAHP7u1Rcu4 l75w1xInsg== In-Reply-To: <1D01F3E8-BEFF-4938-B538-C3657AA31742@zytor.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 1/9/2025 1:46 AM, H. Peter Anvin wrote: > On January 8, 2025 12:14:18 PM PST, Dave Hansen wrote: >> On 1/7/25 18:36, Xin Li (Intel) wrote: >>> + * Another option is to leave the FRED RSP0 MSR as-is, because the RESET >>> + * state of FRED MSRs is zero and INIT does not change the value of the >>> + * FRED MSRs in a CPU offline/online cycle. But it doesn't seem safe to >>> + * depend on the properties of INIT as that's way too many things that >>> + * could cause bugs. >> >> Wouldn't that also open us up to kexec problems? If the last kernel >> (maybe not even Linux) left RSP0 set, then the current kernel might >> eventually try to run userspace with the old kernel's RSP0 value. >> > > Yeah, it is a nonstarter. I believe Xin was trying to document the problems with *not* doing this, so someone doesn't have the bright idea to "optimize" this later. > exactly ;)