net/mlx5_core: Add base sriov support

net/mlx5_core: Add base sriov support

This patch adds SRIOV base support for mlx5 supported devices. The same
driver is used for both PFs and VFs; VFs are identified by the driver
through the flag MLX5_PCI_DEV_IS_VF added to the pci table entries.
Virtual functions are created as usual through writing a value to the
sriov_numvs sysfs file of the PF device. Upon instantiating VFs, they will
all be probed by the driver on the hypervisor. One can gracefully unbind
them through /sys/bus/pci/drivers/mlx5_core/unbind.

mlx5_wait_for_vf_pages() was added to ensure that when a VF dies without
executing proper teardown, the hypervisor driver waits till all of the
pages that were allocated at the hypervisor to maintain its operation
are returned.

In order for the VF to be operational, the PF needs to call enable_hca
for it. This can be done before the VFs are created through a call to
pci_enable_sriov.

If the there are VFs assigned to a VMs when the driver of the PF is
unloaded, all the VF will experience system error and PF driver unloads
cleanly; in this case pci_disable_sriov is not called and the devices
will show when running lspci. Once the PF driver is reloaded, it will
sync its data structures which maintain state on its VFs.

Signed-off-by: Eli Cohen <eli@mellanox.com>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>