[PATCH] xen/pciback: Make missing GSI non-fatal

[Jason Andryuk <jason.andryuk@xxxxxxx>]

A PCI may not have a legacy IRQ.  In that case, do not fail assigning
to the pciback stub.  Instead just skip xen_pvh_setup_gsi().

This will leave psdev->gsi == -1.  In that case, when reading the value
via IOCTL_PRIVCMD_PCIDEV_GET_GSI, return -ENOENT.  Userspace can used
this to distinquish from other errors.

Fixes: b166b8ab4189 ("xen/pvh: Setup gsi for passthrough device")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Jason Andryuk <jason.andryuk@xxxxxxx>
---
 drivers/xen/acpi.c                 |  4 ++--
 drivers/xen/xen-pciback/pci_stub.c | 17 ++++++++++-------
 2 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/drivers/xen/acpi.c b/drivers/xen/acpi.c
index d2ee605c5ca1..d6ab0cb3ba3f 100644
--- a/drivers/xen/acpi.c
+++ b/drivers/xen/acpi.c
@@ -101,7 +101,7 @@ int xen_acpi_get_gsi_info(struct pci_dev *dev,
 
        pin = dev->pin;
        if (!pin)
-               return -EINVAL;
+               return -ENOENT;
 
        entry = acpi_pci_irq_lookup(dev, pin);
        if (entry) {
@@ -116,7 +116,7 @@ int xen_acpi_get_gsi_info(struct pci_dev *dev,
                gsi = -1;
 
        if (gsi < 0)
-               return -EINVAL;
+               return -ENOENT;
 
        *gsi_out = gsi;
        *trigger_out = trigger;
diff --git a/drivers/xen/xen-pciback/pci_stub.c 
b/drivers/xen/xen-pciback/pci_stub.c
index b616b7768c3b..9715c2f70586 100644
--- a/drivers/xen/xen-pciback/pci_stub.c
+++ b/drivers/xen/xen-pciback/pci_stub.c
@@ -240,6 +240,9 @@ static int pcistub_get_gsi_from_sbdf(unsigned int sbdf)
        if (!psdev)
                return -ENODEV;
 
+       if (psdev->gsi == -1)
+               return -ENOENT;
+
        return psdev->gsi;
 }
 #endif
@@ -475,14 +478,14 @@ static int pcistub_init_device(struct pcistub_device 
*psdev)
 #ifdef CONFIG_XEN_ACPI
        if (xen_initial_domain() && xen_pvh_domain()) {
                err = xen_acpi_get_gsi_info(dev, &gsi, &trigger, &polarity);
-               if (err) {
-                       dev_err(&dev->dev, "Fail to get gsi info!\n");
-                       goto config_release;
+               if (err && err != -ENOENT) {
+                       dev_err(&dev->dev, "Failed to get gsi info! %d\n", err);
+               } else if (!err) {
+                       err = xen_pvh_setup_gsi(gsi, trigger, polarity);
+                       if (err)
+                               goto config_release;
+                       psdev->gsi = gsi;
                }
-               err = xen_pvh_setup_gsi(gsi, trigger, polarity);
-               if (err)
-                       goto config_release;
-               psdev->gsi = gsi;
        }
 #endif
 
-- 
2.34.1