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Message-ID: <alpine.DEB.2.00.1011231237170.2373@kaball-desktop>
Date: Tue, 23 Nov 2010 12:55:37 +0000
From: Stefano Stabellini <stefano.stabellini@...citrix.com>
To: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
CC: Stefano Stabellini <Stefano.Stabellini@...citrix.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Jeremy Fitzhardinge <Jeremy.Fitzhardinge@...rix.com>,
"xen-devel@...ts.xensource.com" <xen-devel@...ts.xensource.com>
Subject: Re: [PATCH] xen: use PHYSDEVOP_get_free_pirq to implement
find_unbound_pirq
On Mon, 22 Nov 2010, Konrad Rzeszutek Wilk wrote:
> On Sat, Nov 20, 2010 at 01:19:31AM +0000, Stefano Stabellini wrote:
> > On Fri, 19 Nov 2010, Konrad Rzeszutek Wilk wrote:
> > > On Fri, Nov 19, 2010 at 01:58:03PM +0000, Stefano Stabellini wrote:
> > > > Use PHYSDEVOP_get_free_pirq to implement find_unbound_pirq
> > > >
> > > > Use the new hypercall PHYSDEVOP_get_free_pirq to ask Xen to allocate a
> > > > pirq. Remove the unsupported PHYSDEVOP_get_nr_pirqs hypercall to get the
> > > > amount of pirq available.
> > > >
> > > > Signed-off-by: Stefano Stabellini <stefano.stabellini@...citrix.com>
> > > >
> > > > diff --git a/drivers/xen/events.c b/drivers/xen/events.c
> > > > index 321a0c8..ffd286e 100644
> > > > --- a/drivers/xen/events.c
> > > > +++ b/drivers/xen/events.c
> > > > @@ -382,12 +382,17 @@ static int get_nr_hw_irqs(void)
> > > > return ret;
> > > > }
> > > >
> > > > -/* callers of this function should make sure that PHYSDEVOP_get_nr_pirqs
> > > > - * succeeded otherwise nr_pirqs won't hold the right value */
> > > > -static int find_unbound_pirq(void)
> > > > +static int find_unbound_pirq(int type)
> > > > {
> > > > - int i;
> > > > - for (i = nr_pirqs-1; i >= 0; i--) {
> > > > + int rc, i;
> > > > + struct physdev_get_free_pirq op_get_free_pirq;
> > > > + op_get_free_pirq.type = type;
> > > > +
> > > > + rc = HYPERVISOR_physdev_op(PHYSDEVOP_get_free_pirq, &op_get_free_pirq);
> > > > + if (!rc)
> > > > + return op_get_free_pirq.pirq;
> > > > +
> > > > + for (i = 16; i <= nr_pirqs-1; i++) {
> > >
> > > 16? No no. Why not re-use the old loop, like so:
> > >
> > > for (i = nr_pirqs-1; i >= 0; i--) {
> > >
> >
> > Because we don't know the real nr_pirqs anymore (PHYSDEVOP_get_nr_pirqs
> > has been removed), so it is highly possible that starting from the top
> > down would give us pirq numbers out of range in Xen. Therefore we need
> > to start from the bottom up, and the bottom for Xen is 16.
>
> Right, I forgot about the hypercall call. How about using LEGACY_IRQ instead then?
>
Do you mean NR_IRQS_LEGACY? Yeah, I could do that.
> >
> >
> > > > if (pirq_to_irq[i] < 0)
> > > > return i;
> > > > }
> > > > @@ -669,7 +674,7 @@ void xen_allocate_pirq_msi(char *name, int *irq, int *pirq)
> > > > if (*irq == -1)
> > > > goto out;
> > > >
> > > > - *pirq = find_unbound_pirq();
> > > > + *pirq = find_unbound_pirq(MAP_PIRQ_TYPE_MSI);
> > > > if (*pirq == -1)
> > > > goto out;
> > > >
> > > > @@ -1504,23 +1509,12 @@ void xen_callback_vector(void) {}
> > > > void __init xen_init_IRQ(void)
> > > > {
> > > > int i, rc;
> > > > - struct physdev_nr_pirqs op_nr_pirqs;
> > > >
> > > > cpu_evtchn_mask_p = kcalloc(nr_cpu_ids, sizeof(struct cpu_evtchn_s),
> > > > GFP_KERNEL);
> > > > irq_info = kcalloc(nr_irqs, sizeof(*irq_info), GFP_KERNEL);
> > > >
> > > > - rc = HYPERVISOR_physdev_op(PHYSDEVOP_get_nr_pirqs, &op_nr_pirqs);
> > > > - if (rc < 0) {
> > > > - nr_pirqs = nr_irqs;
> > > > - if (rc != -ENOSYS)
> > > > - printk(KERN_WARNING "PHYSDEVOP_get_nr_pirqs returned rc=%d\n", rc);
> > > > - } else {
> > > > - if (xen_pv_domain() && !xen_initial_domain())
> > > > - nr_pirqs = max((int)op_nr_pirqs.nr_pirqs, nr_irqs);
> > > > - else
> > > > - nr_pirqs = op_nr_pirqs.nr_pirqs;
> > > > - }
> > > > + nr_pirqs = nr_irqs;
> > >
> > > Why not just get rid of nr_pirgs altogether then? And use 'nr_irqs' instead?
> > >
> >
> > Yeah, I guess we could do that. I kept it around just to make it more
> > obvious that the max pirq number is different from nr_irqs and we don't
> > know what the exact value is.
>
>
> But with this change it is the same, is it not?
>
> "nr_pirgs = nr_irqs;"
>
> Or when you say "max pirq" you are referring to something else altogether?
>
Yes, it is the same. I guess a comment would be better then.
Appended the updated version of this patch.
---
Use PHYSDEVOP_get_free_pirq to implement find_unbound_pirq
Use the new hypercall PHYSDEVOP_get_free_pirq to ask Xen to allocate a
pirq. Remove the unsupported PHYSDEVOP_get_nr_pirqs hypercall to get the
amount of pirq available.
Signed-off-by: Stefano Stabellini <stefano.stabellini@...citrix.com>
diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index 2811bb9..9f19daa 100644
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -105,7 +105,6 @@ struct irq_info
static struct irq_info *irq_info;
static int *pirq_to_irq;
-static int nr_pirqs;
static int *evtchn_to_irq;
struct cpu_evtchn_s {
@@ -385,12 +384,17 @@ static int get_nr_hw_irqs(void)
return ret;
}
-/* callers of this function should make sure that PHYSDEVOP_get_nr_pirqs
- * succeeded otherwise nr_pirqs won't hold the right value */
-static int find_unbound_pirq(void)
+static int find_unbound_pirq(int type)
{
- int i;
- for (i = nr_pirqs-1; i >= 0; i--) {
+ int rc, i;
+ struct physdev_get_free_pirq op_get_free_pirq;
+ op_get_free_pirq.type = type;
+
+ rc = HYPERVISOR_physdev_op(PHYSDEVOP_get_free_pirq, &op_get_free_pirq);
+ if (!rc)
+ return op_get_free_pirq.pirq;
+
+ for (i = NR_IRQS_LEGACY; i <= nr_irqs-1; i++) {
if (pirq_to_irq[i] < 0)
return i;
}
@@ -611,9 +615,9 @@ int xen_map_pirq_gsi(unsigned pirq, unsigned gsi, int shareable, char *name)
spin_lock(&irq_mapping_update_lock);
- if ((pirq > nr_pirqs) || (gsi > nr_irqs)) {
+ if ((pirq > nr_irqs) || (gsi > nr_irqs)) {
printk(KERN_WARNING "xen_map_pirq_gsi: %s %s is incorrect!\n",
- pirq > nr_pirqs ? "nr_pirqs" :"",
+ pirq > nr_irqs ? "nr_pirqs" :"",
gsi > nr_irqs ? "nr_irqs" : "");
goto out;
}
@@ -672,7 +676,7 @@ void xen_allocate_pirq_msi(char *name, int *irq, int *pirq)
if (*irq == -1)
goto out;
- *pirq = find_unbound_pirq();
+ *pirq = find_unbound_pirq(MAP_PIRQ_TYPE_MSI);
if (*pirq == -1)
goto out;
@@ -1506,26 +1510,17 @@ void xen_callback_vector(void) {}
void __init xen_init_IRQ(void)
{
- int i, rc;
- struct physdev_nr_pirqs op_nr_pirqs;
+ int i;
cpu_evtchn_mask_p = kcalloc(nr_cpu_ids, sizeof(struct cpu_evtchn_s),
GFP_KERNEL);
irq_info = kcalloc(nr_irqs, sizeof(*irq_info), GFP_KERNEL);
- rc = HYPERVISOR_physdev_op(PHYSDEVOP_get_nr_pirqs, &op_nr_pirqs);
- if (rc < 0) {
- nr_pirqs = nr_irqs;
- if (rc != -ENOSYS)
- printk(KERN_WARNING "PHYSDEVOP_get_nr_pirqs returned rc=%d\n", rc);
- } else {
- if (xen_pv_domain() && !xen_initial_domain())
- nr_pirqs = max((int)op_nr_pirqs.nr_pirqs, nr_irqs);
- else
- nr_pirqs = op_nr_pirqs.nr_pirqs;
- }
- pirq_to_irq = kcalloc(nr_pirqs, sizeof(*pirq_to_irq), GFP_KERNEL);
- for (i = 0; i < nr_pirqs; i++)
+ /* We are using nr_irqs as the maximum number of pirq available but
+ * that number is actually chosen by Xen and we don't know exactly
+ * what it is. Be careful choosing high pirq numbers. */
+ pirq_to_irq = kcalloc(nr_irqs, sizeof(*pirq_to_irq), GFP_KERNEL);
+ for (i = 0; i < nr_irqs; i++)
pirq_to_irq[i] = -1;
evtchn_to_irq = kcalloc(NR_EVENT_CHANNELS, sizeof(*evtchn_to_irq),
diff --git a/include/xen/interface/physdev.h b/include/xen/interface/physdev.h
index 2b2c66c..534cac8 100644
--- a/include/xen/interface/physdev.h
+++ b/include/xen/interface/physdev.h
@@ -188,6 +188,16 @@ struct physdev_nr_pirqs {
uint32_t nr_pirqs;
};
+/* type is MAP_PIRQ_TYPE_GSI or MAP_PIRQ_TYPE_MSI
+ * the hypercall returns a free pirq */
+#define PHYSDEVOP_get_free_pirq 23
+struct physdev_get_free_pirq {
+ /* IN */
+ int type;
+ /* OUT */
+ uint32_t pirq;
+};
+
/*
* Notify that some PIRQ-bound event channels have been unmasked.
* ** This command is obsolete since interface version 0x00030202 and is **
--
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