xen: do not map the same GSI twice in PVHVM guests.

commit 68c2c39a76b094e9b2773e5846424ea674bf2c46 upstream.

PV on HVM guests map GSIs into event channels. At restore time the
event channels are resumed by restore_pirqs.

Device drivers might try to register the same GSI again through ACPI at
restore time, but the GSI has already been mapped and bound by
restore_pirqs. This patch detects these situations and avoids
 mapping the same GSI multiple times.

Without this patch we get:
(XEN) irq.c:2235: dom4: pirq 23 or emuirq 28 already mapped
and waste a pirq.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/pci/xen.c b/arch/x86/pci/xen.c
index d99346ea8fdb4317b74fded709c6bd971b3a066c..4c262f6ff7cd8b4fe329ccd3ededa17204290253 100644 (file)
--- a/arch/x86/pci/xen.c
+++ b/arch/x86/pci/xen.c
@@ -64,6 +64,10 @@ static int xen_register_pirq(u32 gsi, int gsi_override, int triggering,
        int shareable = 0;
        char *name;
 
+       irq = xen_irq_from_gsi(gsi);
+       if (irq > 0)
+               return irq;
+
        if (set_pirq)
                pirq = gsi;
 

diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index e5e5812a1014cbf2c306ec802391980a7926754c..25ea05acb7a0979524ecc08b54a2e9716c813982 100644 (file)
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -604,7 +604,7 @@ static void disable_pirq(struct irq_data *data)
        disable_dynirq(data);
 }
 
-static int find_irq_by_gsi(unsigned gsi)
+int xen_irq_from_gsi(unsigned gsi)
 {
        struct irq_info *info;
 
@@ -618,6 +618,7 @@ static int find_irq_by_gsi(unsigned gsi)
 
        return -1;
 }
+EXPORT_SYMBOL_GPL(xen_irq_from_gsi);
 
 /*
  * Do not make any assumptions regarding the relationship between the
@@ -637,7 +638,7 @@ int xen_bind_pirq_gsi_to_irq(unsigned gsi,
 
        mutex_lock(&irq_mapping_update_lock);
 
-       irq = find_irq_by_gsi(gsi);
+       irq = xen_irq_from_gsi(gsi);
        if (irq != -1) {
                printk(KERN_INFO "xen_map_pirq_gsi: returning irq %d for gsi %u\n",
                       irq, gsi);

diff --git a/include/xen/events.h b/include/xen/events.h
index 0f773708e02c034f624ca61a3e186bb8e9d68080..04399b28e821bf694a58d706e0b6c9f66e9c7d9f 100644 (file)
--- a/include/xen/events.h
+++ b/include/xen/events.h
@@ -103,6 +103,9 @@ int xen_irq_from_pirq(unsigned pirq);
 /* Return the pirq allocated to the irq. */
 int xen_pirq_from_irq(unsigned irq);
 
+/* Return the irq allocated to the gsi */
+int xen_irq_from_gsi(unsigned gsi);
+
 /* Determine whether to ignore this IRQ if it is passed to a guest. */
 int xen_test_irq_shared(int irq);