[PATCH v6 4/6] PCI/IOV: Check that VF BAR fits within the reservation

[Michał Winiarski]

When the resource representing VF MMIO BAR reservation is created, its
size is always large enough to accommodate the BAR of all SR-IOV Virtual
Functions that can potentially be created (total VFs). If for whatever
reason it's not possible to accommodate all VFs - the resource is not
assigned and no VFs can be created.

The following patch will allow VF BAR size to be modified by drivers at
a later point in time, which means that the check for resource
assignment is no longer sufficient.

Add an additional check that verifies that VF BAR for all enabled VFs
fits within the underlying reservation resource.

Signed-off-by: Michał Winiarski <michal.winiarski at intel.com>
---
 drivers/pci/iov.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
index cbf335725d4fb..861273ad9a580 100644
--- a/drivers/pci/iov.c
+++ b/drivers/pci/iov.c
@@ -646,8 +646,13 @@ static int sriov_enable(struct pci_dev *dev, int nr_virtfn)
 
 	nres = 0;
 	for (i = 0; i < PCI_SRIOV_NUM_BARS; i++) {
+		resource_size_t vf_bar_sz =
+			pci_iov_resource_size(dev,
+					      pci_resource_num_from_vf_bar(i));
 		bars |= (1 << pci_resource_num_from_vf_bar(i));
 		res = &dev->resource[pci_resource_num_from_vf_bar(i)];
+		if (vf_bar_sz * nr_virtfn > resource_size(res))
+			continue;
 		if (res->parent)
 			nres++;
 	}
-- 
2.49.0