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

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Message-ID: <20250226200134.29759-1-jason.andryuk@amd.com>
Date: Wed, 26 Feb 2025 15:01:34 -0500
From: Jason Andryuk <jason.andryuk@....com>
To: Juergen Gross <jgross@...e.com>, Stefano Stabellini
	<sstabellini@...nel.org>, Oleksandr Tyshchenko
	<oleksandr_tyshchenko@...m.com>, Jiqian Chen <Jiqian.Chen@....com>, Huang Rui
	<ray.huang@....com>
CC: Jason Andryuk <jason.andryuk@....com>, <stable@...r.kernel.org>,
	<xen-devel@...ts.xenproject.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH] xen/pciback: Make missing GSI non-fatal

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@...r.kernel.org
Signed-off-by: Jason Andryuk <jason.andryuk@....com>
---
 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