From fea93a3e5d5e6a09eb153866d2ce60ea3287a70d Mon Sep 17 00:00:00 2001
From: Wei Liu <wei.liu@kernel.org>
Date: Mon, 1 Jul 2024 20:26:05 +0000
Subject: [PATCH] PCI: hv: Return zero, not garbage, when reading
PCI_INTERRUPT_PIN
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The intent of the code snippet is to always return 0 for both
PCI_INTERRUPT_LINE and PCI_INTERRUPT_PIN.
The check misses PCI_INTERRUPT_PIN. This patch fixes that.
This is discovered by this call in VFIO:
pci_read_config_byte(vdev->pdev, PCI_INTERRUPT_PIN, &pin);
The old code does not set *val to 0 because it misses the check for
PCI_INTERRUPT_PIN. Garbage is returned in that case.
Fixes: 4daace0d8ce8 ("PCI: hv: Add paravirtual PCI front-end for Microsoft Hyper-V VMs")
Link: https://lore.kernel.org/linux-pci/20240701202606.129606-1-wei.liu@kernel.org
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Reviewed-by: Michael Kelley <mhklinux@outlook.com>
Cc: stable@kernel.org
---
drivers/pci/controller/pci-hyperv.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
index 5992280e8110b..cdd5be16021dd 100644
--- a/drivers/pci/controller/pci-hyperv.c
+++ b/drivers/pci/controller/pci-hyperv.c
@@ -1130,8 +1130,8 @@ static void _hv_pcifront_read_config(struct hv_pci_dev *hpdev, int where,
PCI_CAPABILITY_LIST) {
/* ROM BARs are unimplemented */
*val = 0;
- } else if (where >= PCI_INTERRUPT_LINE && where + size <=
- PCI_INTERRUPT_PIN) {
+ } else if ((where >= PCI_INTERRUPT_LINE && where + size <= PCI_INTERRUPT_PIN) ||
+ (where >= PCI_INTERRUPT_PIN && where + size <= PCI_MIN_GNT)) {
/*
* Interrupt Line and Interrupt PIN are hard-wired to zero
* because this front-end only supports message-signaled
--
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