[PATCH v4 5/7] PCI/IOV: Check that VF BAR fits within the reservation

[Michał Winiarski]

VF MMIO resource reservation, either created by system firmware and
inherited by Linux PCI subsystem or created by the subsystem itself,
should contain enough space to fit the BAR of all SR-IOV Virtual
Functions that can potentially be created (total VFs supported by the
device).

However, that assumption only holds in an environment where VF BAR size
can't be modified.

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 | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
index 79143c1bc7bb4..5de828e5a26ea 100644
--- a/drivers/pci/iov.c
+++ b/drivers/pci/iov.c
@@ -645,10 +645,14 @@ static int sriov_enable(struct pci_dev *dev, int nr_virtfn)
 
 	nres = 0;
 	for (i = 0; i < PCI_SRIOV_NUM_BARS; i++) {
+		int vf_bar_sz = pci_iov_resource_size(dev,
+						      pci_resource_to_iov(i));
 		bars |= (1 << pci_resource_to_iov(i));
 		res = &dev->resource[pci_resource_to_iov(i)];
-		if (res->parent)
-			nres++;
+		if (!res->parent || vf_bar_sz * nr_virtfn > resource_size(res))
+			continue;
+
+		nres++;
 	}
 	if (nres != iov->nres) {
 		pci_err(dev, "not enough MMIO resources for SR-IOV\n");
-- 
2.47.0