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

From: Konrad Rzeszutek Wilk
Date: Wed Aug 01 2012 - 10:37:55 EST


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@xxxxxxxxxxxxx>
> ---
> 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
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