Check the device negotiated TPH support status before parsing the TPH
extended capability. Return zero length to hide the capability from
userspace if TPH is disabled during topology negotiation.

Signed-off-by: Chengwen Feng <fengchengwen@huawei.com>
---
 drivers/vfio/pci/vfio_pci_config.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/vfio/pci/vfio_pci_config.c b/drivers/vfio/pci/vfio_pci_config.c
index a10ed733f0e3..5c6ab172df6c 100644
--- a/drivers/vfio/pci/vfio_pci_config.c
+++ b/drivers/vfio/pci/vfio_pci_config.c
@@ -22,6 +22,7 @@
 
 #include <linux/fs.h>
 #include <linux/pci.h>
+#include <linux/pci-tph.h>
 #include <linux/uaccess.h>
 #include <linux/vfio.h>
 #include <linux/slab.h>
@@ -1450,6 +1451,8 @@ static int vfio_ext_cap_len(struct vfio_pci_core_device *vdev, u16 ecap, u16 epo
 		byte &= PCI_DPA_CAP_SUBSTATE_MASK;
 		return PCI_DPA_BASE_SIZEOF + byte + 1;
 	case PCI_EXT_CAP_ID_TPH:
+		if (!pcie_tph_supported(pdev, false))
+			return 0;
 		ret = pci_read_config_dword(pdev, epos + PCI_TPH_CAP, &dword);
 		if (ret)
 			return pcibios_err_to_errno(ret);
-- 
2.17.1