Re: [PATCH v1 09/12] accel/xen/xen-all: export xenstore_record_dm_state

[Oleksandr Tyshchenko <olekstysh@xxxxxxxxx>]

On Thu, Oct 27, 2022 at 12:24 PM Alex Bennée <alex.bennee@xxxxxxxxxx> wrote:

Hello all

Vikram Garhwal <vikram.garhwal@xxxxxxx> writes:

> xenstore_record_dm_state() will also be used in aarch64 xenpv machine.
>
> Signed-off-by: Vikram Garhwal <vikram.garhwal@xxxxxxx>
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxx>
> ---
>  accel/xen/xen-all.c  | 2 +-
>  include/hw/xen/xen.h | 2 ++
>  2 files changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/accel/xen/xen-all.c b/accel/xen/xen-all.c
> index 69aa7d018b..276625b78b 100644
> --- a/accel/xen/xen-all.c
> +++ b/accel/xen/xen-all.c
> @@ -100,7 +100,7 @@ void xenstore_store_pv_console_info(int i, Chardev *chr)
>  }
> 
> 
> -static void xenstore_record_dm_state(struct xs_handle *xs, const char *state)
> +void xenstore_record_dm_state(struct xs_handle *xs, const char *state)
>  {
>      char path[50];
> 
> diff --git a/include/hw/xen/xen.h b/include/hw/xen/xen.h
> index afdf9c436a..31e9538a5c 100644
> --- a/include/hw/xen/xen.h
> +++ b/include/hw/xen/xen.h
> @@ -9,6 +9,7 @@
>   */
> 
>  #include "exec/cpu-common.h"
> +#include <xenstore.h>

This is breaking a bunch of the builds and generally we try and avoid
adding system includes in headers (apart from osdep.h) for this reason.
In fact there is a comment just above to that fact.

I think you can just add struct xs_handle to typedefs.h (or maybe just
xen.h) and directly include xenstore.h in xen-all.c following the usual
rules:

  https://qemu.readthedocs.io/en/latest/devel/style.html#include-directives

It might be worth doing an audit to see what else is including xen.h
needlessly or should be using sysemu/xen.h.

> 
>  /* xen-machine.c */
>  enum xen_mode {
> @@ -31,5 +32,6 @@ qemu_irq *xen_interrupt_controller_init(void);
>  void xenstore_store_pv_console_info(int i, Chardev *chr);
> 
>  void xen_register_framebuffer(struct MemoryRegion *mr);
> +void xenstore_record_dm_state(struct xs_handle *xs, const char *state);
> 
>  #endif /* QEMU_HW_XEN_H */


--
Alex Bennée

For considering:

I think this patch and some other changes done in "[PATCH v1 10/12] hw/arm: introduce xenpv machine" (the opening of Xen interfaces and calling xenstore_record_dm_state() in hw/arm/xen_arm.c:xen_init_ioreq())

could be avoided if we enable the Xen accelerator (either by passing "-M xenpv,accel=xen" or by adding mc->default_machine_opts = "accel=xen"; to hw/arm/xen_arm.c:xen_arm_machine_class_init() or by some other method).

These actions are already done in accel/xen/xen-all.c:xen_init(). Please note, that I am not too familiar with that code, so there might be nuances. 

Besides that, Xen accelerator will be needed for the xen-mapcache to be in use (this is needed for mapping guest memory), there are a few xen_enabled() checks spreading around that code to perform Xen specific actions.

--

Regards,

Oleksandr Tyshchenko