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PCI/IOV: Use VF0 cached config space size for other VFs

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Cache the config space size from VF0 and use it for all other VFs instead
of reading it from the config space of each VF.  We assume that it will be
the same across all associated VFs.

This is an optimization when enabling SR-IOV on a device with many VFs.

Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
[bhelgaas: use CONFIG_PCI_IOV (not CONFIG_PCI_ATS)]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
This commit is contained in:
KarimAllah Ahmed
2018-10-11 11:49:58 -05:00
committed by Bjorn Helgaas
parent 7876320f88
commit 975bb8b4dc
3 changed files with 20 additions and 0 deletions
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drivers/pci/probe.c
+17
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@@ -1438,12 +1438,29 @@ static int pci_cfg_space_size_ext(struct pci_dev *dev)
return PCI_CFG_SPACE_EXP_SIZE;
}
#ifdef CONFIG_PCI_IOV
static bool is_vf0(struct pci_dev *dev)
{
if (pci_iov_virtfn_devfn(dev->physfn, 0) == dev->devfn &&
pci_iov_virtfn_bus(dev->physfn, 0) == dev->bus->number)
return true;
return false;
}
#endif
int pci_cfg_space_size(struct pci_dev *dev)
{
int pos;
u32 status;
u16 class;
#ifdef CONFIG_PCI_IOV
/* Read cached value for all VFs except for VF0 */
if (dev->is_virtfn && !is_vf0(dev))
return dev->physfn->sriov->cfg_size;
#endif
if (dev->bus->bus_flags & PCI_BUS_FLAGS_NO_EXTCFG)
return PCI_CFG_SPACE_SIZE;