Unverified Commit fea93a3e authored by Wei Liu's avatar Wei Liu Committed by Krzysztof Wilczyński
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PCI: hv: Return zero, not garbage, when reading PCI_INTERRUPT_PIN 

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: 4daace0d ("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: default avatarWei Liu <wei.liu@kernel.org>
Signed-off-by: default avatarKrzysztof Wilczyński <kwilczynski@kernel.org>
Reviewed-by: default avatarMichael Kelley <mhklinux@outlook.com>
Cc: stable@kernel.org
parent 1613e604

drivers/pci/controller/pci-hyperv.c

+2 −2
Original line number Diff line number Diff line
@@ -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