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 (m64_segsize >> 1) and adds comment to explain the reason for it. Signed-off-by: Wei Yang <weiy...@linux.vnet.ibm.com> --- arch/powerpc/platforms/powernv/pci-ioda.c | 22 +++++++++++++++++----- 1 file changed, 17 insertions(+), 5 deletions(-) diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c index 4da0f50..3e8c0b4 100644 --- a/arch/powerpc/platforms/powernv/pci-ioda.c +++ b/arch/powerpc/platforms/powernv/pci-ioda.c @@ -2688,7 +2688,7 @@ static void pnv_pci_ioda_fixup_iov_resources(struct pci_dev *pdev) struct pnv_phb *phb; struct resource *res; int i; - resource_size_t size; + resource_size_t size, gate; struct pci_dn *pdn; int mul, total_vfs; @@ -2704,6 +2704,17 @@ static void pnv_pci_ioda_fixup_iov_resources(struct pci_dev *pdev) total_vfs = pci_sriov_get_totalvfs(pdev); mul = phb->ioda.total_pe; + /* + * If bigger than or equal to half 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. + */ + gate = phb->ioda.m64_segsize >> 1; for (i = 0; i < PCI_SRIOV_NUM_BARS; i++) { res = &pdev->resource[i + PCI_IOV_RESOURCES]; @@ -2718,10 +2729,11 @@ 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); + /* bigger than or equal to gate */ + 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 _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev