Re: [PATCH v4 1/2] pci: Identify Enhanced Allocation (EA) BAR Equivalent resources

[Bjorn Helgaas <helgaas@kernel.org>]

On Thu, Feb 11, 2016 at 04:52:24PM -0800, Sean O. Stalley wrote:
> From: Alex Williamson <alex.williamson@redhat.com>
> 
> Resource flags are exposed to userspace via the sysfs "resource" file.
> lspci reads the sysfs file to determine resource properties.
> Adding this flag allows lspci to distinguish between [virtual]
> and [enhanced] resources.
> 
> If the resource is not aligned, userspace could deduce where
> the resource is EA based on the size & address fields.
> However, a flag indicating whether a PCI resource is a traditional BAR
> or BAR equivalent seems like a much simpler solution and works if the
> EA resource is aligned.
> 
> Although this patchset only improves lspci, other uses for this
> flag have been identified. For example, vfio makes assumptions
> about alignment and sizing, and runs into problems when attempting
> to emulate a BAR Equivalent EA resource.
> 
> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
> Signed-off-by: Sean O. Stalley <sean.stalley@intel.com>

I applied this to pci/resource and intend to merge it for v4.7.

> ---
>  drivers/pci/pci.c      | 2 +-
>  include/linux/ioport.h | 7 +++++++
>  2 files changed, 8 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..88816f9 100644
> --- a/include/linux/ioport.h
> +++ b/include/linux/ioport.h
> @@ -25,7 +25,11 @@ struct resource {
>  
>  /*
>   * IO resources have these defined flags.
> + *
> + * PCI devices expose these flags to userspace in the "resource" sysfs file,
> + * Moving them around could break stuff, so don't do it.
>   */
> +
>  #define IORESOURCE_BITS		0x000000ff	/* Bus-specific bits */
>  
>  #define IORESOURCE_TYPE_BITS	0x00001f00	/* Resource type */
> @@ -97,6 +101,7 @@ struct resource {
>  #define IORESOURCE_IO_SPARSE		(1<<2)
>  
>  /* PCI ROM control bits (IORESOURCE_BITS) */
> +
>  #define IORESOURCE_ROM_ENABLE		(1<<0)	/* ROM is enabled, same as PCI_ROM_ADDRESS_ENABLE */
>  #define IORESOURCE_ROM_SHADOW		(1<<1)	/* ROM is copy at C000:0 */
>  #define IORESOURCE_ROM_COPY		(1<<2)	/* ROM is alloc'd copy, resource field overlaid */
> @@ -105,6 +110,8 @@ 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)
>  
>  /* helpers to define resources */
>  #define DEFINE_RES_NAMED(_start, _size, _name, _flags)			\
> -- 
> 1.9.1
> 
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