Messages in this thread | | | Date | Tue, 21 Mar 2023 09:59:53 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH v5 20/34] x86/fred: add a machine check entry stub for FRED |
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On Tue, Mar 21, 2023 at 12:04:47AM +0000, Li, Xin3 wrote: > > > Unlike IDT, no need to save/restore dr7 in FRED machine check handler. > > > > Given how fragile MCE is, the question should be, do we ever want hw > > breakpoints to happen while it is running? > > HW breakpoints still work if they are properly configured. > > > If the hw-breakpoint handler trips on the same memory fail that got us into the > > mce the first time, we're dead. > > Right. > > Unless the MCIP bit is turned off any subsequent #MC goes to shutdown > ("machine is screwed"). > > It's the kernel debugger's responsibility to decide how to proceed in such > cases. But if the kernel debugger itself is in a screwed memory region, we > are soooooo dead.
Yeah, so I would much prefer, for robustness sake, to start out with not allowing #DB in MCE -- much like today.
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