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A comment on Google's response to Reptar CPU vulnerability. Parent comment

Re:Google's response to Reptar CPU vulnerability by toast0 on Thursday December 14, 2023 @02:13AM (#38638653)
I think you can load microcode after boot, it's just more likely to have weird effects, especially with older processors.

For VMs running in GCP, they do migrate VMs across machines from time to time, and you could handwave a process where they take a machkne, update the hypervisor image with new microcode, migrate all VMs off the machine, then make it available to receive VM migrations. Migrating a VM is disruptive, although the disruption is brief.

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Re:Google's response to Reptar CPU vulnerability by eichin on Thursday December 14, 2023 @06:37PM (#38648993)
Oh, that's a good point, you could even determine that your hypervisor doesn't touch any changed microcode paths, and just pause the VMs, take the update, and unpause. (Still seems... brave, maybe? Or at least involves more information that I'd expect anyone outside of intel to actually have, I guess.)
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