Re: [PATCH v4 01/23] plugins: add types for callbacks related to certain discontinuities

[Pierrick Bouvier <pierrick.bouvier@linaro.org>]

Hi Julian,

On 5/11/25 6:13 AM, Julian Ganz wrote:
> The plugin API allows registration of callbacks for a variety of VCPU
> related events, such as VCPU reset, idle and resume. However, traps of
> any kind, i.e. interrupts or exceptions, were previously not covered.
> These kinds of events are arguably quite significant and usually go hand
> in hand with a PC discontinuity. On most platforms, the discontinuity
> also includes a transition from some "mode" to another. Thus, plugins
> for the analysis of (virtualized) embedded systems may benefit from or
> even require the possiblity to perform work on the occurance of an
> interrupt or exception.
> 
> This change introduces the concept of such a discontinuity event in the
> form of an enumeration. Currently only traps are covered. Specifically
> we (loosely) define interrupts, exceptions and host calls across all
> platforms. In addition, this change introduces a type to use for
> callback functions related to such events. Since possible modes and the
> enumeration of interupts and exceptions vary greatly between different
> architectures, the callback type only receives the VCPU id, the type of
> event as well as the old and new PC.
> 
> Signed-off-by: Julian Ganz <neither@nut.email>
> ---
>   include/qemu/plugin.h      |  1 +
>   include/qemu/qemu-plugin.h | 44 ++++++++++++++++++++++++++++++++++++++
>   2 files changed, 45 insertions(+)
> 

[...]

> +/**
> + * typedef qemu_plugin_vcpu_discon_cb_t - vcpu discontinuity callback
> + * @id: plugin ID
> + * @vcpu_index: the current vcpu context
> + * @type: the type of discontinuity
> + * @from_pc: the source of the discontinuity, e.g. the PC before the
> + *           transition
> + * @to_pc: the PC pointing to the next instruction to be executed
> + *
> + * The excact semantics of @from_pc depends on @the type of discontinuity. For

s/excact/exact

> + * interrupts, @from_pc will point to the next instruction which would have
> + * been executed. For exceptions and host calls, @from_pc will point to the
> + * instruction that caused the exception or issued the host call. Note that
> + * in the case of exceptions, the instruction may not be retired and thus not
> + * observable via general instruction exec callbacks. The same may be the case
> + * for some host calls such as hypervisor call "exceptions".
> + */

thanks for respinning this series.

Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>