On 25/1/08 10:19, "Andi Kleen" <[EMAIL PROTECTED]> wrote: >> Whether this a problem in light of Xen spurious faults depends on whether >> NMI handlers touch dynamically-allocated data. > > How do you define dynamically-allocated data?
Anything that could have been a read-only pte or ldt page in a previous life with no intervening TLB flush. So get_free_page(), kmalloc(), vmalloc(), ... Actually I think we are fine, now I think about it some more, because we only clear the software NMI-in-flight flag if the guest executes IRET via the hypervisor. Most Xen Linux guests only do IRET via the hypervisor when the current context is an NMI handler (additionally x86_64 also does so when returning to ring 3). Most importantly for this case, we will *not* IRET via the hypervisor when returning from a #PF context nested in an NMI context. Hence the NMI-in-flight flag will not be cleared, and guest virtual NMIs will not nest. So that's a relief! -- Keir -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
