PCI/IOV: Mark VFs as not implementing PCI_COMMAND_MEMORY

For VFs, the Memory Space Enable bit in the Command Register is
hard-wired to 0.

Add a new bit to signify devices where the Command Register Memory
Space Enable bit does not control the device's response to MMIO
accesses.

Fixes: abafbc55 ("vfio-pci: Invalidate mmaps and block MMIO access on disabled memory")
Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

drivers/pci/iov.c

@@ -180,6 +180,7 @@ int pci_iov_add_virtfn(struct pci_dev *dev, int id)
 	virtfn->device = iov->vf_device;
 	virtfn->is_virtfn = 1;
 	virtfn->physfn = pci_dev_get(dev);
+	virtfn->no_command_memory = 1;
 
 	if (id == 0)
 		pci_read_vf_config_common(virtfn);

include/linux/pci.h

@@ -445,6 +445,7 @@ struct pci_dev {
 	unsigned int	is_probed:1;		/* Device probing in progress */
 	unsigned int	link_active_reporting:1;/* Device capable of reporting link active */
 	unsigned int	no_vf_scan:1;		/* Don't scan for VFs after IOV enablement */
+	unsigned int	no_command_memory:1;	/* No PCI_COMMAND_MEMORY */
 	pci_dev_flags_t dev_flags;
 	atomic_t	enable_cnt;	/* pci_enable_device has been called */