Subject: [RFC PATCH 0/1] KVM: PPC: Inform userspace about singlestep support

From: Fabiano Rosas <[email-masked]>
Date: Wed, 20 Mar 2019 15:39:49 -0300

I am looking for a way to inform userspace about the lack of an
implementation in KVM HV for single stepping of instructions
(KVM_GUESTDGB_SINGLESTEP bit from SET_GUEST_DEBUG ioctl).

This will be used by QEMU to decide whether to attempt a call to the
set_guest_debug ioctl (for BookE, KVM PR) or fallback to a QEMU only
implementation (for KVM HV).

QEMU thread:
http://patchwork.ozlabs.org/cover/1049811/

My current proposal is to introduce a ppc-specific capability for
this. However I'm not sure if this would be better as a cap common for
all architectures or even if it should report on all of the possible
set_guest_debug flags to cover for the future.

Please comment. Thanks.

Fabiano Rosas (1):
  KVM: PPC: Report single stepping capability

 arch/powerpc/kvm/powerpc.c | 5 +++++
 include/uapi/linux/kvm.h   | 1 +
 2 files changed, 6 insertions(+)

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2.20.1