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Mon, 27 Jul 2026 20:36:27 +0000 Message-ID: Date: Mon, 27 Jul 2026 13:36:25 -0700 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] x86/microcode/intel: Panic on partial microcode update To: Dave Hansen , "Maciej W. Rozycki" CC: , , , "Ingo Molnar" , , , References: <20260630191350.3837-1-chang.seok.bae@intel.com> <4f2a4841-0a73-4f44-aec8-890734660a9c@intel.com> Content-Language: en-US From: "Chang S. 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I double-checked with the microcode guy, and here are what I heard so far: * The microcode implementation makes best effort to avoid partial updates in the first place * If an update leaves any critical state, e.g. data corruption and serious security breach, the processor will terminate execution rather than relying on the OS to take action. * That said, no implementation can perfectly cover every possible case. At the same time, panicking on every partial update could be also an overkill. It will depend on the specific failure condition in detail. Then, they've defined those bits seemingly intended to summary the condition at abstraction. I think the first two points have played in this thread already. There seems to be some caution, specifically around the authentication-failure as per spec. Perhaps it might be reassuring if handling that case conservatively (unless too much complicated). In summary, I think options are: 1. Panic on any partial update is the most conservative and secure option, but it may unnecessarily disrupt systems and users 2. Warn admins that the system has entered a taint state, assuming the processor handles truly unrecoverable cases itself. 3. Different reactions - for example, panic on an authentication failure but warn/taint otherwise. Thanks, Chang