Re: [PATCH 09/24] xen/arm: compile and run xenbus

[Konrad Rzeszutek Wilk <konrad.wilk-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>]

On Thu, Jul 26, 2012 at 04:33:51PM +0100, Stefano Stabellini wrote:
> bind_evtchn_to_irqhandler can legitimately return 0 (irq 0): it is not
> an error.
> 
> If Linux is running as an HVM domain and is running as Dom0, use
> xenstored_local_init to initialize the xenstore page and event channel.
> 
> Signed-off-by: Stefano Stabellini <stefano.stabellini-mvvWK6WmYclDPfheJLI6IQ@public.gmane.org>
> ---
>  drivers/xen/xenbus/xenbus_comms.c |    2 +-
>  drivers/xen/xenbus/xenbus_probe.c |   27 +++++++++++++++++----------
>  drivers/xen/xenbus/xenbus_xs.c    |    1 +
>  3 files changed, 19 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/xen/xenbus/xenbus_comms.c b/drivers/xen/xenbus/xenbus_comms.c
> index 52fe7ad..c5aa55c 100644
> --- a/drivers/xen/xenbus/xenbus_comms.c
> +++ b/drivers/xen/xenbus/xenbus_comms.c
> @@ -224,7 +224,7 @@ int xb_init_comms(void)
>  		int err;
>  		err = bind_evtchn_to_irqhandler(xen_store_evtchn, wake_waiting,
>  						0, "xenbus", &xb_waitq);
> -		if (err <= 0) {
> +		if (err < 0) {
>  			printk(KERN_ERR "XENBUS request irq failed %i\n", err);
>  			return err;
>  		}
> diff --git a/drivers/xen/xenbus/xenbus_probe.c b/drivers/xen/xenbus/xenbus_probe.c
> index b793723..3ae47c2 100644
> --- a/drivers/xen/xenbus/xenbus_probe.c
> +++ b/drivers/xen/xenbus/xenbus_probe.c
> @@ -729,16 +729,23 @@ static int __init xenbus_init(void)
>  	xenbus_ring_ops_init();
>  
>  	if (xen_hvm_domain()) {
> -		uint64_t v = 0;
> -		err = hvm_get_parameter(HVM_PARAM_STORE_EVTCHN, &v);
> -		if (err)
> -			goto out_error;
> -		xen_store_evtchn = (int)v;
> -		err = hvm_get_parameter(HVM_PARAM_STORE_PFN, &v);
> -		if (err)
> -			goto out_error;
> -		xen_store_mfn = (unsigned long)v;
> -		xen_store_interface = ioremap(xen_store_mfn << PAGE_SHIFT, PAGE_SIZE);
> +		if (xen_initial_domain()) {
> +			err = xenstored_local_init();
> +			xen_store_interface =
> +				phys_to_virt(xen_store_mfn << PAGE_SHIFT);
> +		} else {
> +			uint64_t v = 0;
> +			err = hvm_get_parameter(HVM_PARAM_STORE_EVTCHN, &v);
> +			if (err)
> +				goto out_error;
> +			xen_store_evtchn = (int)v;
> +			err = hvm_get_parameter(HVM_PARAM_STORE_PFN, &v);
> +			if (err)
> +				goto out_error;
> +			xen_store_mfn = (unsigned long)v;
> +			xen_store_interface =
> +				ioremap(xen_store_mfn << PAGE_SHIFT, PAGE_SIZE);
> +		}

This, and along with the Hybrid PV dom0 (not yet posted, but it was doing
similar manipulation here) is getting more and more like a rat-mess.


Any chance we can just abstract the three different XenStore access
ways and just have something like this:

	enum {
		USE_UNKNOWN
		USE_HVM,
		USE_PV,
		USE_LOCAL
		USE_ALREADY_INIT
	};
	int usage = USE_UNKNOWN;
	if (xen_pv_domain())
		usage = USE_PV;
	if (xen_hvm_domain())
		usage = USE_HVM;
	if (xen_initial_domain())
		usage = USE_LOCAL;

	if (xen_start_info->store_evtchn)
		usage = USE_ALREADY_INIT;
	
	.. other overwrites..

	switch (usage) {
		.. blah blah.
	}


>  		xen_store_evtchn = xen_start_info->store_evtchn;
>  		xen_store_mfn = xen_start_info->store_mfn;
> diff --git a/drivers/xen/xenbus/xenbus_xs.c b/drivers/xen/xenbus/xenbus_xs.c
> index d1c217b..f7feb3d 100644
> --- a/drivers/xen/xenbus/xenbus_xs.c
> +++ b/drivers/xen/xenbus/xenbus_xs.c
> @@ -44,6 +44,7 @@
>  #include <linux/rwsem.h>
>  #include <linux/module.h>
>  #include <linux/mutex.h>
> +#include <asm/xen/hypervisor.h>
>  #include <xen/xenbus.h>
>  #include <xen/xen.h>
>  #include "xenbus_comms.h"
> -- 
> 1.7.2.5