On Fri, Jan 22, 2016 at 02:04:53PM -0800, Sean O. Stalley wrote:
> From: Alex Williamson <alex.williamson@xxxxxxxxxx>
>
> We've done a pretty good job of abstracting EA from drivers,
> but there are some cases where flaging resources as EA would be
> useful. Specifically, EA is flexabable when it comes to resource
Heh, "flexabable" :)
> alignment & sizing. This can create issues when existing software
> makes assumptions about the PCI resources.
>
> For example, lspci assumes any PCI resource exposed by the kernel
> that isn't visible in standard configspace comes from a VF BAR.
> vfio makes assumptions about alignment and sizing, and runs into
> problems when attempting to emulate a BAR Equivalent EA resource.
>
> To facilitate that, a flag indicating whether a PCI resource is a
> traditional BAR or BAR equivalent seems much nicer than attempting
> to deduce where the resource came from from the size & address fields
> (which is impossible if a EA resource happens naturally aligned).
>
> Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
> Signed-off-by: Sean O. Stalley <sean.stalley@xxxxxxxxx>
> ---
> drivers/pci/pci.c | 2 +-
> include/linux/ioport.h | 2 ++
> 2 files changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index d1a7105..8ff678c 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -2229,7 +2229,7 @@ void pci_pm_init(struct pci_dev *dev)
>
> static unsigned long pci_ea_flags(struct pci_dev *dev, u8 prop)
> {
> - unsigned long flags = IORESOURCE_PCI_FIXED;
> + unsigned long flags = IORESOURCE_PCI_FIXED | IORESOURCE_PCI_EA_BEI;
>
> switch (prop) {
> case PCI_EA_P_MEM:
> diff --git a/include/linux/ioport.h b/include/linux/ioport.h
> index 24bea08..5acc194 100644
> --- a/include/linux/ioport.h
> +++ b/include/linux/ioport.h
> @@ -105,6 +105,8 @@ struct resource {
> /* PCI control bits. Shares IORESOURCE_BITS with above PCI ROM. */
> #define IORESOURCE_PCI_FIXED (1<<4) /* Do not move resource */
>
> +/* PCI Enhanced Allocation defined BAR equivalent resource */
> +#define IORESOURCE_PCI_EA_BEI (1<<5)
Hmmm, I didn't realize until I read the lspci patch that the resource
flags are exposed via sysfs (I think in resource_show()) and are thus
part of the sysfs ABI. It would be nice to have a comment to that
effect here in ioport.h so we don't move bits and inadvertently break
something.
The changelog should also connect the dots a little bit more, e.g.,
mention the sysfs file affected by this patch, and that this currently
only makes lspci print slightly more correct output.
> /* helpers to define resources */
> #define DEFINE_RES_NAMED(_start, _size, _name, _flags) \
> --
> 1.9.1
>
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