Re: [Xen-devel] [PATCH 7/7] arch.monitor: move bits to common (arch_domain to domain)

[Tamas K Lengyel <tamas@xxxxxxxxxxxxx>]

On Mon, Feb 8, 2016 at 9:58 AM, Corneliu ZUZU <czuzu@xxxxxxxxxxxxxxx> wrote:

This patch moves bitfield members for single-step, software-breakpoint and
guest-request monitor vm-events from the arch-side (struct arch_domain) to
the common-side (struct domain). Ctrl-reg bits (i.e. write_ctrlreg_* members)
are left on the arch-side, because control-registers number can vary across
architectures.

Signed-off-by: Corneliu ZUZU <czuzu@xxxxxxxxxxxxxxx>

Technically this looks fine, but I do wonder if and what plans you have to actually implement these events for ARM. I haven't spent too much time looking into it, but I'm not aware of equivalent features on ARM to Intel MTF (singlestepping) or to software-breakpoint trapping. The only instruction I know that functionally comes close to software-breakpoint trapping (INT3) is the SMC instruction which can be trapped into the VMM, but I would not call that a "breakpoint" in the traditional sense.

Tamas

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