At the moment 64bit-prefetchable window can be maximum 64GB, which is
currently got from device tree. This means that in shared mode the maximum
supported VF BAR size is 64GB/256=256MB. While this size could exhaust the
whole 64bit-prefetchable window. This is a design decision to set a
boundary to 64MB of the VF BAR size. Since VF BAR size with 64MB would
occupy a quarter of the 64bit-prefetchable window, this is affordable.
This patch replaces magic limit of 64MB with "gate", which is 1/4 of the
M64 Segment Size(m64_segsize >> 2) and adds comment to explain the reason
for it.
Signed-off-by: Wei Yang <weiy...@linux.vnet.ibm.com>
Reviewed-by: Gavin Shan <gws...@linux.vent.ibm.com>
---
arch/powerpc/platforms/powernv/pci-ioda.c | 28 +++++++++++++++++++---------
1 file changed, 19 insertions(+), 9 deletions(-)
diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c
b/arch/powerpc/platforms/powernv/pci-ioda.c
index de7db1d..b8bc51f 100644
--- a/arch/powerpc/platforms/powernv/pci-ioda.c
+++ b/arch/powerpc/platforms/powernv/pci-ioda.c
@@ -2696,8 +2696,9 @@ static void pnv_pci_init_ioda_msis(struct pnv_phb *phb) {
}
#ifdef CONFIG_PCI_IOV
static void pnv_pci_ioda_fixup_iov_resources(struct pci_dev *pdev)
{
- struct pci_controller *hose;
- struct pnv_phb *phb;
+ struct pci_controller *hose = pci_bus_to_host(pdev->bus);
+ struct pnv_phb *phb = hose->private_data;
+ const resource_size_t gate = phb->ioda.m64_segsize >> 2;
struct resource *res;
int i;
resource_size_t size;
@@ -2707,9 +2708,6 @@ static void pnv_pci_ioda_fixup_iov_resources(struct
pci_dev *pdev)
if (!pdev->is_physfn || pdev->is_added)
return;
- hose = pci_bus_to_host(pdev->bus);
- phb = hose->private_data;
-
pdn = pci_get_pdn(pdev);
pdn->vfs_expanded = 0;
pdn->m64_single_mode = false;
@@ -2730,10 +2728,22 @@ static void pnv_pci_ioda_fixup_iov_resources(struct
pci_dev *pdev)
size = pci_iov_resource_size(pdev, i + PCI_IOV_RESOURCES);
- /* bigger than 64M */
- if (size > (1 << 26)) {
- dev_info(&pdev->dev, "PowerNV: VF BAR%d: %pR IOV size
is bigger than 64M, roundup power2\n",
- i, res);
+ /*
+ * If bigger than quarter of M64 segment size, just round up
+ * power of two.
+ *
+ * Generally, one M64 BAR maps one IOV BAR. To avoid conflict
+ * with other devices, IOV BAR size is expanded to be
+ * (total_pe * VF_BAR_size). When VF_BAR_size is half of M64
+ * segment size , the expanded size would equal to half of the
+ * whole M64 space size, which will exhaust the M64 space and
+ * limit the system flexibility. This is a design decision to
+ * set the boundary to quarter of the M64 segment size.
+ */
+ if (size > gate) {
+ dev_info(&pdev->dev, "PowerNV: VF BAR%d: %pR IOV size "
+ "is bigger than %lld, roundup power2\n",
+ i, res, gate);
mul = roundup_pow_of_two(total_vfs);
pdn->m64_single_mode = true;
break;
--
1.7.9.5
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