PCI/VFIO: use pcie_flags_reg instead of access PCI-E Capabilities Register

Currently, we use pcie_flags_reg to cache PCI-E Capabilities Register,
because PCI-E Capabilities Register bits are almost read-only. This patch
use pcie_caps_reg() instead of another access PCI-E Capabilities Register.

Signed-off-by: Yijing Wang <wangyijing@huawei.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

diff --git a/drivers/vfio/pci/vfio_pci_config.c b/drivers/vfio/pci/vfio_pci_config.c
index 072fdac..0e83e8e 100644 (file)
--- a/drivers/vfio/pci/vfio_pci_config.c
+++ b/drivers/vfio/pci/vfio_pci_config.c
@@ -1037,13 +1037,9 @@ static int vfio_cap_len(struct vfio_pci_device *vdev, u8 cap, u8 pos)
                return byte;
        case PCI_CAP_ID_EXP:
                /* length based on version */
-               ret = pci_read_config_word(pdev, pos + PCI_EXP_FLAGS, &word);
-               if (ret)
-                       return pcibios_err_to_errno(ret);
-
                vdev->extended_caps = true;
 
-               if ((word & PCI_EXP_FLAGS_VERS) == 1)
+               if ((pcie_caps_reg(pdev) & PCI_EXP_FLAGS_VERS) == 1)
                        return PCI_CAP_EXP_ENDPOINT_SIZEOF_V1;
                else
                        return PCI_CAP_EXP_ENDPOINT_SIZEOF_V2;