On Thu, Dec 01, 2016 at 02:17:29PM +0000, Lorenzo Pieralisi wrote:
> Hi Bjorn,
>
> Thank you very much for putting this series together !
>
> On Thu, Dec 01, 2016 at 02:29:39AM -0600, Bjorn Helgaas wrote:
> > From: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> >
> > The static MCFG table tells us the base of ECAM space, but it does not
> > reserve the space -- the reservation should be done via a device in the
> > ACPI namespace whose _CRS includes the ECAM region.
> >
> > Add pci_ecam_verify_reservation() to check whether the ECAM space is
> > reserved by an ACPI namespace device. If it is, emit a message showing
> > which device reserves it. If not, emit a "[Firmware Bug]" warning.
>
> I have a question: do we want to carry out a search on a restricted set
> of _HIDs here ? I am not sure we should consider an ECAM region matching
> with a resource in a device _CRS whose _HID/_CID is not part of
> {PNP0c02, PNP0A03, PNP0A08} as a success, actually I think that would be
> a FW bug, right ?
That's a good question. I did it the simplest way I could for now,
but we could extend that if we decide it's necessary. Sometimes I've
been overly zealous about looking for problems and ended up
overengineering things or shooting myself in the foot.
My main goal is to make sure the space is described *somewhere*, which
is enough to keep it from being a land mine.
> > Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> > ---
> > drivers/pci/ecam.c | 21 +++++++++++++++++++++
> > 1 file changed, 21 insertions(+)
> >
> > diff --git a/drivers/pci/ecam.c b/drivers/pci/ecam.c
> > index 43ed08d..3805122 100644
> > --- a/drivers/pci/ecam.c
> > +++ b/drivers/pci/ecam.c
> > @@ -14,6 +14,7 @@
> > * version 2 (GPLv2) along with this source code.
> > */
> >
> > +#include <linux/acpi.h>
> > #include <linux/device.h>
> > #include <linux/io.h>
> > #include <linux/kernel.h>
> > @@ -29,6 +30,24 @@
> > */
> > static const bool per_bus_mapping = !IS_ENABLED(CONFIG_64BIT);
> >
> > +static void pci_ecam_verify_reservation(struct device *dev,
> > + struct resource *ecam)
> > +{
> > +#ifdef CONFIG_ACPI
> > + struct acpi_device *adev;
> > +
> > + adev = acpi_resource_consumer(ecam);
> > + if (!adev) {
> > + dev_warn(dev, FW_BUG "ECAM area %pR not reserved in ACPI namespace\n",
> > + ecam);
> > + return;
> > + }
> > +
> > + dev_info(dev, "ECAM area %pR reserved by %s\n", ecam,
> > + dev_name(&adev->dev));
> > +#endif
> > +}
> > +
> > /*
> > * Create a PCI config space window
> > * - reserve mem region
> > @@ -51,6 +70,8 @@ struct pci_config_window *pci_ecam_create(struct device *dev,
> > if (!cfg)
> > return ERR_PTR(-ENOMEM);
> >
> > + pci_ecam_verify_reservation(dev, cfgres);
> > +
> > cfg->parent = dev;
> > cfg->ops = ops;
> > cfg->busr.start = busr->start;
> >
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