Re: [patch added to 3.12-stable] powerpc/iommu: Remove the dependency on EEH struct in DDW mechanism

["Guilherme G. Piccoli" <gpiccoli@linux.vnet.ibm.com>]

On 07/12/2016 06:41 AM, Jiri Slaby wrote:
> From: "Guilherme G. Piccoli" <gpiccoli@linux.vnet.ibm.com>
>
> This patch has been added to the 3.12 stable tree. If you have any
> objections, please let us know.
>

Jiri, thanks for letting me know. If you added this on 3.12, you need to 
add another commit (that has a fix to this one): 8a934efe9434 
("powerpc/pseries: Fix PCI config address for DDW")

I'm not sure if you already added 8a934efe9434, but in any case I found 
useful to warn you.

Cheers,


Guilherme


> ===============
>
> commit 8445a87f7092bc8336ea1305be9306f26b846d93 upstream.
>
> Commit 39baadbf36ce ("powerpc/eeh: Remove eeh information from pci_dn")
> changed the pci_dn struct by removing its EEH-related members.
> As part of this clean-up, DDW mechanism was modified to read the device
> configuration address from eeh_dev struct.
>
> As a consequence, now if we disable EEH mechanism on kernel command-line
> for example, the DDW mechanism will fail, generating a kernel oops by
> dereferencing a NULL pointer (which turns to be the eeh_dev pointer).
>
> This patch just changes the configuration address calculation on DDW
> functions to a manual calculation based on pci_dn members instead of
> using eeh_dev-based address.
>
> No functional changes were made. This was tested on pSeries, both
> in PHyp and qemu guest.
>
> Fixes: 39baadbf36ce ("powerpc/eeh: Remove eeh information from pci_dn")
> Reviewed-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
> Signed-off-by: Guilherme G. Piccoli <gpiccoli@linux.vnet.ibm.com>
> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
> ---
>   arch/powerpc/platforms/pseries/iommu.c | 24 ++++++++++++------------
>   1 file changed, 12 insertions(+), 12 deletions(-)
>
> diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
> index 261c5095d5d3..88cbecbdbd6f 100644
> --- a/arch/powerpc/platforms/pseries/iommu.c
> +++ b/arch/powerpc/platforms/pseries/iommu.c
> @@ -861,7 +861,8 @@ machine_arch_initcall(pseries, find_existing_ddw_windows);
>   static int query_ddw(struct pci_dev *dev, const u32 *ddw_avail,
>   			struct ddw_query_response *query)
>   {
> -	struct eeh_dev *edev;
> +	struct device_node *dn;
> +	struct pci_dn *pdn;
>   	u32 cfg_addr;
>   	u64 buid;
>   	int ret;
> @@ -872,11 +873,10 @@ static int query_ddw(struct pci_dev *dev, const u32 *ddw_avail,
>   	 * Retrieve them from the pci device, not the node with the
>   	 * dma-window property
>   	 */
> -	edev = pci_dev_to_eeh_dev(dev);
> -	cfg_addr = edev->config_addr;
> -	if (edev->pe_config_addr)
> -		cfg_addr = edev->pe_config_addr;
> -	buid = edev->phb->buid;
> +	dn = pci_device_to_OF_node(dev);
> +	pdn = PCI_DN(dn);
> +	buid = pdn->phb->buid;
> +	cfg_addr = (pdn->busno << 8) | pdn->devfn;
>
>   	ret = rtas_call(ddw_avail[0], 3, 5, (u32 *)query,
>   		  cfg_addr, BUID_HI(buid), BUID_LO(buid));
> @@ -890,7 +890,8 @@ static int create_ddw(struct pci_dev *dev, const u32 *ddw_avail,
>   			struct ddw_create_response *create, int page_shift,
>   			int window_shift)
>   {
> -	struct eeh_dev *edev;
> +	struct device_node *dn;
> +	struct pci_dn *pdn;
>   	u32 cfg_addr;
>   	u64 buid;
>   	int ret;
> @@ -901,11 +902,10 @@ static int create_ddw(struct pci_dev *dev, const u32 *ddw_avail,
>   	 * Retrieve them from the pci device, not the node with the
>   	 * dma-window property
>   	 */
> -	edev = pci_dev_to_eeh_dev(dev);
> -	cfg_addr = edev->config_addr;
> -	if (edev->pe_config_addr)
> -		cfg_addr = edev->pe_config_addr;
> -	buid = edev->phb->buid;
> +	dn = pci_device_to_OF_node(dev);
> +	pdn = PCI_DN(dn);
> +	buid = pdn->phb->buid;
> +	cfg_addr = (pdn->busno << 8) | pdn->devfn;
>
>   	do {
>   		/* extra outputs are LIOBN and dma-addr (hi, lo) */
>