Revert "PCI/IOV: Use VF0 cached config space size for other VFs"

Revert 975bb8b4 ("PCI/IOV: Use VF0 cached config space size for other
VFs"), which attempted to cache the config space size from the first VF to
re-use for subsequent VFs.

The cached value was determined prior to discovering the PCIe capability on
the VF, which resulted in the first VF reporting the correct config space
size (4K), as it has a special case through pci_cfg_space_size(), while all
the other VFs only reported 256 bytes.  As this was only a performance
optimization, we're better off without it.

Fixes: 975bb8b4 ("PCI/IOV: Use VF0 cached config space size for other VFs")
Link: https://lore.kernel.org/r/156046663197.29869.3633634445109057665.stgit@gimli.homeSigned-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: KarimAllah Ahmed <karahmed@amazon.de>
Cc: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Cc: Hao Zheng <yinhe@linux.alibaba.com>

drivers/pci/iov.c

@@ -132,8 +132,6 @@ static void pci_read_vf_config_common(struct pci_dev *virtfn)
 			     &physfn->sriov->subsystem_vendor);
 	pci_read_config_word(virtfn, PCI_SUBSYSTEM_ID,
 			     &physfn->sriov->subsystem_device);
-
-	physfn->sriov->cfg_size = pci_cfg_space_size(virtfn);
 }
 
 int pci_iov_add_virtfn(struct pci_dev *dev, int id)

drivers/pci/pci.h

@@ -293,7 +293,6 @@ struct pci_sriov {
 	u16		driver_max_VFs;	/* Max num VFs driver supports */
 	struct pci_dev	*dev;		/* Lowest numbered PF */
 	struct pci_dev	*self;		/* This PF */
-	u32		cfg_size;	/* VF config space size */
 	u32		class;		/* VF device */
 	u8		hdr_type;	/* VF header type */
 	u16		subsystem_vendor; /* VF subsystem vendor */

drivers/pci/probe.c

@@ -1555,29 +1555,12 @@ static int pci_cfg_space_size_ext(struct pci_dev *dev)
 	return PCI_CFG_SPACE_EXP_SIZE;
 }
 
-#ifdef CONFIG_PCI_IOV
-static bool is_vf0(struct pci_dev *dev)
-{
-	if (pci_iov_virtfn_devfn(dev->physfn, 0) == dev->devfn &&
-	    pci_iov_virtfn_bus(dev->physfn, 0) == dev->bus->number)
-		return true;
-
-	return false;
-}
-#endif
-
 int pci_cfg_space_size(struct pci_dev *dev)
 {
 	int pos;
 	u32 status;
 	u16 class;
 
-#ifdef CONFIG_PCI_IOV
-	/* Read cached value for all VFs except for VF0 */
-	if (dev->is_virtfn && !is_vf0(dev))
-		return dev->physfn->sriov->cfg_size;
-#endif
-
 	if (dev->bus->bus_flags & PCI_BUS_FLAGS_NO_EXTCFG)
 		return PCI_CFG_SPACE_SIZE;