On Wed, Nov 06, 2013 at 12:33:31PM -0800, Yinghai Lu wrote:
> >> > commit 4e5415f02e32c85e902cd9692eab18200e14b347
> >> > Author: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> >> > Date: Wed Nov 6 10:00:51 2013 -0700
> >> >
> >> > PCI: Enable upstream bridges even for VFs on virtual buses
> >> >
> >> > Previously we enabled the upstream PCI-to-PCI bridge only when
> >> > "dev->bus->self != NULL". In the case of a VF on a virtual bus, where
> >> > "bus->self == NULL", we didn't enable the upstream bridge.
> >> >
> >> > This fixes that by enabling the upstream bridge of the PF corresponding to
> >> > the VF.
> >> >
> >> > Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> >> >
> >> > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> >> > index ac40f90..744dc26 100644
> >> > --- a/drivers/pci/pci.c
> >> > +++ b/drivers/pci/pci.c
> >> > @@ -1150,10 +1150,8 @@ static void pci_enable_bridge(struct pci_dev *dev)
> >> > {
> >> > int retval;
> >> >
> >> > - if (!dev)
> >> > - return;
> >> > -
> >> > - pci_enable_bridge(dev->bus->self);
> >> > + if (!pci_is_root_bus(dev->bus))
> >> > + pci_enable_bridge(pci_upstream_bridge(dev));
> >> >
> >> > if (pci_is_enabled(dev)) {
> >> > if (!dev->is_busmaster)
> >> > @@ -1188,7 +1186,8 @@ static int pci_enable_device_flags(struct pci_dev *dev, unsigned long flags)
> >> > if (atomic_inc_return(&dev->enable_cnt) > 1)
> >> > return 0; /* already enabled */
> >> >
> >> > - pci_enable_bridge(dev->bus->self);
> >> > + if (!pci_is_root_bus(dev->bus))
> >> > + pci_enable_bridge(pci_upstream_bridge(dev));
> >> >
> >> > /* only skip sriov related */
> >> > for (i = 0; i <= PCI_ROM_RESOURCE; i++)
> >>
> >> still have problem.
> >>
> >> pci_upstream_bridge() could return NULL. so later pci_enable_bridge()
> >> referring dev->bus could panic, as you remove !dev checking.
> >
> > pci_upstream_bridge(dev) can only return NULL if dev is on a root bus,
> > and we never call pci_enable_bridge() in that case. So I don't see
> > the problem.
>
> how about it is VF and it is on it's own virtual bus ?
> and it will pass !pci_is_root_bus(dev->bus) checking and get into
> pci_enable_bridge(pci_upstream_bridge(dev));
Oh, I see. The problem is when VF is on a virtual bus and the
corresponding PF is on a root bus. Then we have:
pci_is_root_bus(VF) == false
pci_upstream_bridge(VF) == pci_upstream_bridge(PF)
pci_uptream_bridge(PF) == NULL
I guess that's what your suggestion about "caching the return from
pci_upstream_bridge()" was about. Like this:
commit 21ea57bf1311f7a8d1b755d355322a1f077fccb7
Author: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Date: Wed Nov 6 10:11:48 2013 -0700
PCI: Add pci_upstream_bridge()
This adds a pci_upstream_bridge() interface to find the PCI-to-PCI bridge
upstream from a device. This is typically just "dev->bus->self", but in
the case of a VF on a virtual bus, we have to start from the corresponding
PF. Returns NULL if there is no upstream PCI bridge, i.e., if the device
is on a root bus.
Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
diff --git a/include/linux/pci.h b/include/linux/pci.h
index d3a888a..835ec7b 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -480,6 +480,15 @@ static inline bool pci_is_root_bus(struct pci_bus *pbus)
return !(pbus->parent);
}
+static inline struct pci_dev *pci_upstream_bridge(struct pci_dev *dev)
+{
+ dev = pci_physfn(dev);
+ if (pci_is_root_bus(dev->bus))
+ return NULL;
+
+ return dev->bus->self;
+}
+
#ifdef CONFIG_PCI_MSI
static inline bool pci_dev_msi_enabled(struct pci_dev *pci_dev)
{
commit bca690ab580d5c0c4a0c7201f3c42057288add8b
Author: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Date: Wed Nov 6 10:00:51 2013 -0700
PCI: Enable upstream bridges even for VFs on virtual buses
Previously we enabled the upstream PCI-to-PCI bridge only when
"dev->bus->self != NULL". In the case of a VF on a virtual bus, where
"bus->self == NULL", we didn't enable the upstream bridge.
This fixes that by enabling the upstream bridge of the PF corresponding to
the VF.
Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index ac40f90..d3ed931 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1148,12 +1148,12 @@ int pci_reenable_device(struct pci_dev *dev)
static void pci_enable_bridge(struct pci_dev *dev)
{
+ struct pci_dev *bridge;
int retval;
- if (!dev)
- return;
-
- pci_enable_bridge(dev->bus->self);
+ bridge = pci_upstream_bridge(dev);
+ if (bridge)
+ pci_enable_bridge(bridge);
if (pci_is_enabled(dev)) {
if (!dev->is_busmaster)
@@ -1170,6 +1170,7 @@ static void pci_enable_bridge(struct pci_dev *dev)
static int pci_enable_device_flags(struct pci_dev *dev, unsigned long flags)
{
+ struct pci_dev *bridge;
int err;
int i, bars = 0;
@@ -1188,7 +1189,9 @@ static int pci_enable_device_flags(struct pci_dev *dev, unsigned long flags)
if (atomic_inc_return(&dev->enable_cnt) > 1)
return 0; /* already enabled */
- pci_enable_bridge(dev->bus->self);
+ bridge = pci_upstream_bridge(dev);
+ if (bridge)
+ pci_enable_bridge(bridge);
/* only skip sriov related */
for (i = 0; i <= PCI_ROM_RESOURCE; i++)
--
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