Messages in this thread | | | Date | Thu, 29 Aug 2019 06:02:14 -0700 | From | "Raj, Ashok" <> | Subject | Re: [PATCH] x86/microcode: Add an option to reload microcode even if revision is unchanged |
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On Thu, Aug 29, 2019 at 08:09:42AM +0200, Borislav Petkov wrote: > On Wed, Aug 28, 2019 at 10:33:22PM -0700, Ashok Raj wrote: > > During microcode development, its often required to test different versions > > of microcode. Intel microcode loader enforces loading only if the revision is > > greater than what is currently loaded on the cpu. Overriding this behavior > > allows us to reuse the same revision during development cycles. > > This facilty also allows us to share debug microcode with development > > partners for getting feedback before microcode release. > > > > Microcode developers should have other ways to check which > > of their internal version is actually loaded. For e.g. checking a > > temporary MSR for instance. In order to reload the same microcode do as > > shown below. > > > > # echo 2 > /sys/devices/system/cpu/microcode/reload > > > > as root. > > > > > > I tested this on top of the parallel ucode load patch > > > > https://lore.kernel.org/r/1566506627-16536-2-git-send-email-mihai.carabas@oracle.com/ > > > > v2: [Mihai] Address comments from Boris > > - Support for AMD > > - add taint flag > > - removed global force_ucode_load and parameterized it. > > As I've said before, I don't like the churn in this version and how it > turns out. I'll have a look at how to do this cleanly when I get some > free cycles.
Thanks Boris. I'll wait for your updates. I remember your comment on another simplification from the Boris Ostrovsky https://lore.kernel.org/r/20190828191618.GO4920@zn.tnic/
Mihai rolled in your suggestions noted above.
BTW, We only need to force on the late-load. Its not needed during early load.
Cheers, Ashok
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