Re: [PATCH] PCI/VMD: Fix config addressing with bus offsets

[Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>]

[dropped CC stable]

On Tue, Jun 11, 2019 at 03:15:38PM -0600, Jon Derrick wrote:
> VMD config space addressing relies on mapping the BDF of the target into
> the VMD config bar. When using bus number offsets to number the VMD
> domain, the offset needs to be ignored in order to correctly map devices
> to their config space.
> 
> Fixes: 2a5a9c9a20f9 ("PCI: vmd: Add offset to bus numbers if necessary")
> Cc: <stable@vger.kernel.org> # v4.19
> Cc: <stable@vger.kernel.org> # v4.18

Hi Jon,

that's not how stable should be handled. You should always start
by fixing mainline and if there are backports to be fixed too you
should add patch dependencies in the CC area, see:

Documentation/process/stable-kernel-rules.rst

Never add stable to the CC list in the email header, only in the
commit log.

When your patch hits mainline it will trickle back into stable,
if you specified dependencies as described above there is nothing
to do.

Thanks,
Lorenzo

> Signed-off-by: Jon Derrick <jonathan.derrick@intel.com>
> ---
>  drivers/pci/controller/vmd.c | 16 +++++++++-------
>  1 file changed, 9 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
> index fd2dbd7..a59afec 100644
> --- a/drivers/pci/controller/vmd.c
> +++ b/drivers/pci/controller/vmd.c
> @@ -94,6 +94,7 @@ struct vmd_dev {
>  	struct resource		resources[3];
>  	struct irq_domain	*irq_domain;
>  	struct pci_bus		*bus;
> +	u8			busn_start;
>  
>  #ifdef CONFIG_X86_DEV_DMA_OPS
>  	struct dma_map_ops	dma_ops;
> @@ -465,7 +466,8 @@ static char __iomem *vmd_cfg_addr(struct vmd_dev *vmd, struct pci_bus *bus,
>  				  unsigned int devfn, int reg, int len)
>  {
>  	char __iomem *addr = vmd->cfgbar +
> -			     (bus->number << 20) + (devfn << 12) + reg;
> +			     ((bus->number - vmd->busn_start) << 20) +
> +			     (devfn << 12) + reg;
>  
>  	if ((addr - vmd->cfgbar) + len >=
>  	    resource_size(&vmd->dev->resource[VMD_CFGBAR]))
> @@ -588,7 +590,7 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
>  	unsigned long flags;
>  	LIST_HEAD(resources);
>  	resource_size_t offset[2] = {0};
> -	resource_size_t membar2_offset = 0x2000, busn_start = 0;
> +	resource_size_t membar2_offset = 0x2000;
>  
>  	/*
>  	 * Shadow registers may exist in certain VMD device ids which allow
> @@ -630,14 +632,14 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
>  		pci_read_config_dword(vmd->dev, PCI_REG_VMCONFIG, &vmconfig);
>  		if (BUS_RESTRICT_CAP(vmcap) &&
>  		    (BUS_RESTRICT_CFG(vmconfig) == 0x1))
> -			busn_start = 128;
> +			vmd->busn_start = 128;
>  	}
>  
>  	res = &vmd->dev->resource[VMD_CFGBAR];
>  	vmd->resources[0] = (struct resource) {
>  		.name  = "VMD CFGBAR",
> -		.start = busn_start,
> -		.end   = busn_start + (resource_size(res) >> 20) - 1,
> +		.start = vmd->busn_start,
> +		.end   = vmd->busn_start + (resource_size(res) >> 20) - 1,
>  		.flags = IORESOURCE_BUS | IORESOURCE_PCI_FIXED,
>  	};
>  
> @@ -705,8 +707,8 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
>  	pci_add_resource_offset(&resources, &vmd->resources[1], offset[0]);
>  	pci_add_resource_offset(&resources, &vmd->resources[2], offset[1]);
>  
> -	vmd->bus = pci_create_root_bus(&vmd->dev->dev, busn_start, &vmd_ops,
> -				       sd, &resources);
> +	vmd->bus = pci_create_root_bus(&vmd->dev->dev, vmd->busn_start,
> +				       &vmd_ops, sd, &resources);
>  	if (!vmd->bus) {
>  		pci_free_resource_list(&resources);
>  		irq_domain_remove(vmd->irq_domain);
> -- 
> 1.8.3.1
>