On 13/02/2023 11:48 pm, Kirill A. Shutemov wrote: > TDX guests are not allowed to clear CR4.MCE. Attempt to clear it leads > to #VE. > > Preserve the flag during kexec. > > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> That's unfortunate for TDX, but in a non-TDX system you must never maintain CR4.MCE into kexec. Async events, including NMIs, cannot be taken between this point and the target having set itself up into it's intended operating mode. During this period you get all kinds of fun with type confusion in the IDT/TSS and/or not having a safe stack to service the event. A clean shutdown from not having machine checks enabled is far preferable to trying to deliver an #MC in purgatory. That, or you're welcome to debug the next bug report I get where (amazingly) an NMI managed to hit with a good stack in the new context, but most of the old context (IDT, TSS and .text) still intact enough to start emitting a very confused oops onto serial... ~Andrew _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
