Messages in this thread | | | From | Andy Lutomirski <> | Date | Mon, 17 Nov 2014 16:55:27 -0800 | Subject | Re: [RFC PATCH] x86, entry: Switch stacks on a paranoid entry from userspace |
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On Mon, Nov 17, 2014 at 4:22 PM, Luck, Tony <tony.luck@intel.com> wrote: >> It could also be interesting to tweak mce_panic to not actually panic >> the machine but to try to return and stop the test instead. Then real >> debugging could be possible :) > > The lost cpu is *really* lost. Warm reset doesn't fix the machine, I usually > have to do a full power cycle.
How is it even possible that I did that with a few lines of asm?
Could this be a hardware bug? Is there some condition that causes #MC delivery to wedge hard enough that even INIT/RESET stops working? Or possibly some CPU got stuck in SMM -- I have no idea what warm reset does these days.
My initial attempts to test machine_check in KVM using IPIs are having some issues, probably because I'm not acking the interrupt. I can do it once, but then it stops working.
Here's the patch to improve the timeout messages, but given the degree of wedgedness, I can guess what it'll say:
https://git.kernel.org/cgit/linux/kernel/git/luto/linux.git/commit/?h=x86/paranoid&id=e5cbd9d141bde651ecb20f0b65ad13bcef2468d0
--Andy
> > -Tony
-- Andy Lutomirski AMA Capital Management, LLC
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