Eduardo Habkost wrote: > This patch adds an interface to set a function to be called on crash time, > on each CPU. The function will be set by code that enables virtualization > extensions on the CPUs (i.e. KVM). It will be called once on each CPU > by machine_crash_shutdown(), and should do the very least to disable > virt extensions on the CPU where it is being called. > > The function will be used by KVM to disable virtualization before halting > the CPUs, otherwise the booting of the kdump kernel may hang. It does > hang, when vmx is enabled, and I wouldn't be surprised if having svm > enabled also causes problems. > > The functions that set the function pointer uses RCU synchronization, > just in case the crash NMI is triggered while KVM is unloading. > > We can't just use the same notifiers used at reboot time (that are used > by non-crash-dump kexec), because at crash time some CPUs may have IRQs > disabled, so we can't use IPIs. The crash shutdown code use NMIs to > tell the other CPUs to be halted, so the notifier call is hooked into > the CPU halting code that is on the crash shutdown NMI handler. > > +static void (*virt_disable_fn)(unsigned int cpu); > Since you never use the cpu argument, I suggest dropping it. -- I have a truly marvellous patch that fixes the bug which this signature is too narrow to contain.
