• Vitaly Kuznetsov's avatar
    x86/xen: Support kexec/kdump in HVM guests by doing a soft reset · 0b34a166
    Vitaly Kuznetsov authored
    Currently there is a number of issues preventing PVHVM Xen guests from
    doing successful kexec/kdump:
      - Bound event channels.
      - Registered vcpu_info.
      - PIRQ/emuirq mappings.
      - shared_info frame after XENMAPSPACE_shared_info operation.
      - Active grant mappings.
    Basically, newly booted kernel stumbles upon already set up Xen
    interfaces and there is no way to reestablish them. In Xen-4.7 a new
    feature called 'soft reset' is coming. A guest performing kexec/kdump
    operation is supposed to call SCHEDOP_shutdown hypercall with
    SHUTDOWN_soft_reset reason before jumping to new kernel. Hypervisor
    (with some help from toolstack) will do full domain cleanup (but
    keeping its memory and vCPU contexts intact) returning the guest to
    the state it had when it was first booted and thus allowing it to
    start over.
    Doing SHUTDOWN_soft_reset on Xen hypervisors which don't support it is
    probably OK as by default all unknown shutdown reasons cause domain
    destroy with a message in toolstack log: 'Unknown shutdown reason code
    5. Destroying domain.'  which gives a clue to what the problem is and
    eliminates false expectations.
    Signed-off-by: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
    Cc: <stable@vger.kernel.org>
    Signed-off-by: default avatarDavid Vrabel <david.vrabel@citrix.com>