Commit e5fc7345 authored by Stefano Stabellini's avatar Stefano Stabellini
Browse files

xen: 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.

This fixes find_unbound_pirq that otherwise would return a number
starting from nr_irqs that might very well be out of range in Xen.

The symptom of this bug is that when you passthrough an MSI capable pci
device to a PV on HVM guest, Linux would fail to enable MSIs on the
device.

Signed-off-by: default avatarStefano Stabellini <stefano.stabellini@eu.citrix.com>
parent e8a7e48b

drivers/xen/events.c

+20 −25
Original line number Diff line number Diff line
@@ -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 = 0; i < nr_irqs; i++) {

		if (pirq_to_irq[i] < 0)

			return i;

	}
@@ -611,10 +615,10 @@ 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" :"",

			gsi > nr_irqs ? "nr_irqs" : "");

			pirq > nr_irqs ? "pirq" :"",

			gsi > nr_irqs ? "gsi" : "");

		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),

include/xen/interface/physdev.h

+10 −0
Original line number Diff line number Diff line
@@ -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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