[Very RFC 23/46] powerpc/eeh: Moving finding the parent PE into the platform

[Alexey Kardashevskiy]

On 20/11/2019 12:28, Oliver O'Halloran wrote:
> Currently the generic EEH code uses the pci_dn of a device to look up the
> PE of the device's parent bridge, or physical function. The generic
> function to insert the edev (and possibly create the eeh_pe) is called
> from the probe functions already so this is a relatively minor change.
> 
> The existing lookup method moves into the pseries platform and PowerNV
> can choose the PE based on the bus heirachy instead.


The pseries search is also based on sort of bus hierarchy (the pci_dn
tree is that). A short essay about the difference between PCI trees and
pci_dn trees would help (reminder: draw that picture of a set of trees
and lists we got there).


> 
> Signed-off-by: Oliver O'Halloran <oohall at gmail.com>
> ---
> "parent" meaning "parent of the PE that actually contains this edev"
> is stupid, but it's stupid consistent with what's there already. Also
> I couldn't think of a way to fix it without adding a bunch of boring
> boilerplate at the call sites.
> 
> FIXME: I think I introduced a bug here. Currently we coalase a switch's
> upstream port bus and the downstream port bus into a single PE since
> they're a single failure domain. That seems to have been broken by
> this patch, but whatever.


Not clear at all where/how this got broken, pointers would help,
preferably as a comment in the code.

Apart from that,

Reviewed-by: Alexey Kardashevskiy <aik at ozlabs.ru>



Thanks,


> ---
>  arch/powerpc/include/asm/eeh.h               |  2 +-
>  arch/powerpc/kernel/eeh_pe.c                 | 54 ++++-------------
>  arch/powerpc/platforms/powernv/eeh-powernv.c | 25 +++++++-
>  arch/powerpc/platforms/pseries/eeh_pseries.c | 61 ++++++++++++++++----
>  4 files changed, 86 insertions(+), 56 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/eeh.h b/arch/powerpc/include/asm/eeh.h
> index e109bfd3dd57..70d3e01dbe9d 100644
> --- a/arch/powerpc/include/asm/eeh.h
> +++ b/arch/powerpc/include/asm/eeh.h
> @@ -295,7 +295,7 @@ struct eeh_pe *eeh_phb_pe_get(struct pci_controller *phb);
>  struct eeh_pe *eeh_pe_next(struct eeh_pe *pe, struct eeh_pe *root);
>  struct eeh_pe *eeh_pe_get(struct pci_controller *phb,
>  			  int pe_no, int config_addr);
> -int eeh_add_to_parent_pe(struct eeh_dev *edev);
> +int eeh_add_to_parent_pe(struct eeh_pe *parent, struct eeh_dev *edev);
>  int eeh_rmv_from_parent_pe(struct eeh_dev *edev);
>  void eeh_pe_update_time_stamp(struct eeh_pe *pe);
>  void *eeh_pe_traverse(struct eeh_pe *root,
> diff --git a/arch/powerpc/kernel/eeh_pe.c b/arch/powerpc/kernel/eeh_pe.c
> index 831f363f1732..520c249f19d3 100644
> --- a/arch/powerpc/kernel/eeh_pe.c
> +++ b/arch/powerpc/kernel/eeh_pe.c
> @@ -318,56 +318,23 @@ struct eeh_pe *eeh_pe_get(struct pci_controller *phb,
>  	return pe;
>  }
>  
> -/**
> - * eeh_pe_get_parent - Retrieve the parent PE
> - * @edev: EEH device
> - *
> - * The whole PEs existing in the system are organized as hierarchy
> - * tree. The function is used to retrieve the parent PE according
> - * to the parent EEH device.
> - */
> -static struct eeh_pe *eeh_pe_get_parent(struct eeh_dev *edev)
> -{
> -	struct eeh_dev *parent;
> -	struct pci_dn *pdn = eeh_dev_to_pdn(edev);
> -
> -	/*
> -	 * It might have the case for the indirect parent
> -	 * EEH device already having associated PE, but
> -	 * the direct parent EEH device doesn't have yet.
> -	 */
> -	if (edev->physfn)
> -		pdn = pci_get_pdn(edev->physfn);
> -	else
> -		pdn = pdn ? pdn->parent : NULL;
> -	while (pdn) {
> -		/* We're poking out of PCI territory */
> -		parent = pdn_to_eeh_dev(pdn);
> -		if (!parent)
> -			return NULL;
> -
> -		if (parent->pe)
> -			return parent->pe;
> -
> -		pdn = pdn->parent;
> -	}
> -
> -	return NULL;
> -}
> -
>  /**
>   * eeh_add_to_parent_pe - Add EEH device to parent PE
> + * @parent: PE to create additional PEs under
>   * @edev: EEH device
>   *
> - * Add EEH device to the parent PE. If the parent PE already
> - * exists, the PE type will be changed to EEH_PE_BUS. Otherwise,
> - * we have to create new PE to hold the EEH device and the new
> - * PE will be linked to its parent PE as well.
> + * Add EEH device to the PE in edev->pe_config_addr. If the PE
> + * already exists then we'll add it to that. Otherwise a new
> + * PE is created, and inserted into the PE tree below @parent.
> + * If @parent is NULL, then it will be inserted under the PHB
> + * PE for edev->controller.
> + *
> + * In either case @edev is added to the PE's device list.
>   */
> -int eeh_add_to_parent_pe(struct eeh_dev *edev)
> +int eeh_add_to_parent_pe(struct eeh_pe *parent, struct eeh_dev *edev)
>  {
>  	int config_addr = edev->bdfn;
> -	struct eeh_pe *pe, *parent;
> +	struct eeh_pe *pe;
>  
>  	/* Check if the PE number is valid */
>  	if (!eeh_has_flag(EEH_VALID_PE_ZERO) && !edev->pe_config_addr) {
> @@ -431,7 +398,6 @@ int eeh_add_to_parent_pe(struct eeh_dev *edev)
>  	 * to PHB directly. Otherwise, we have to associate the
>  	 * PE with its parent.
>  	 */
> -	parent = eeh_pe_get_parent(edev);
>  	if (!parent) {
>  		parent = eeh_phb_pe_get(edev->controller);
>  		if (!parent) {
> diff --git a/arch/powerpc/platforms/powernv/eeh-powernv.c b/arch/powerpc/platforms/powernv/eeh-powernv.c
> index 7aba18e08996..49a932ff092a 100644
> --- a/arch/powerpc/platforms/powernv/eeh-powernv.c
> +++ b/arch/powerpc/platforms/powernv/eeh-powernv.c
> @@ -358,6 +358,25 @@ static int pnv_eeh_write_config(struct eeh_dev *edev,
>  	return pnv_pci_cfg_write(pdn, where, size, val);
>  }
>  
> +static struct eeh_pe *pnv_eeh_pe_get_parent(struct pci_dev *pdev)
> +{
> +	struct pnv_phb *phb = pci_bus_to_pnvhb(pdev->bus);
> +	struct pci_dev *parent = pdev->bus->self;
> +
> +#ifdef CONFIG_PCI_IOV
> +	if (pdev->is_virtfn)
> +		parent = pdev->physfn;
> +#endif
> +
> +	if (parent) {
> +		struct pnv_ioda_pe *ioda_pe = pnv_ioda_get_pe(parent);
> +
> +		return eeh_pe_get(phb->hose, ioda_pe->pe_number, 0);
> +	}
> +
> +	return NULL;
> +}
> +
>  /**
>   * pnv_eeh_probe - Do probe on PCI device
>   * @pdev: pci_dev to probe
> @@ -368,6 +387,7 @@ static struct eeh_dev *pnv_eeh_probe_pdev(struct pci_dev *pdev)
>  {
>  	struct pnv_phb *phb = pci_bus_to_pnvhb(pdev->bus);
>  	struct pci_controller *hose = phb->hose;
> +	struct eeh_pe *parent_pe;
>  	struct eeh_dev *edev;
>  	uint32_t pcie_flags;
>  	int ret;
> @@ -450,8 +470,11 @@ static struct eeh_dev *pnv_eeh_probe_pdev(struct pci_dev *pdev)
>  
>  	edev->pe_config_addr = phb->ioda.pe_rmap[config_addr];
>  
> +	/* find the PE that contains this PE, might be NULL */
> +	parent_pe = pnv_eeh_pe_get_parent(pdev);
> +
>  	/* Create PE */
> -	ret = eeh_add_to_parent_pe(edev);
> +	ret = eeh_add_to_parent_pe(parent_pe, edev);
>  	if (ret) {
>  		eeh_edev_warn(edev, "Failed to add device to PE (code %d)\n", ret);
>  		return NULL;
> diff --git a/arch/powerpc/platforms/pseries/eeh_pseries.c b/arch/powerpc/platforms/pseries/eeh_pseries.c
> index 13a8c274554a..b4a92c24fd45 100644
> --- a/arch/powerpc/platforms/pseries/eeh_pseries.c
> +++ b/arch/powerpc/platforms/pseries/eeh_pseries.c
> @@ -70,11 +70,12 @@ void pseries_pcibios_bus_add_device(struct pci_dev *pdev)
>  	eeh_add_device_early(pdn);
>  #ifdef CONFIG_PCI_IOV
>  	if (pdev->is_virtfn) {
> +		struct eeh_pe *physfn_pe = pci_dev_to_eeh_dev(pdev->physfn)->pe;
>  		struct eeh_dev *edev = pdn_to_eeh_dev(pdn);
>  
>  		edev->pe_config_addr =  (pdn->busno << 16) | (pdn->devfn << 8);
>  		eeh_rmv_from_parent_pe(edev); /* Remove as it is adding to bus pe */
> -		eeh_add_to_parent_pe(edev);   /* Add as VF PE type */
> +		eeh_add_to_parent_pe(physfn_pe, edev); /* Add as VF PE type */
>  	}
>  #endif
>  	eeh_add_device_late(pdev);
> @@ -220,6 +221,43 @@ static int pseries_eeh_find_ecap(struct pci_dn *pdn, int cap)
>  	return 0;
>  }
>  
> +/**
> + * pseries_eeh_pe_get_parent - Retrieve the parent PE
> + * @edev: EEH device
> + *
> + * The whole PEs existing in the system are organized as hierarchy
> + * tree. The function is used to retrieve the parent PE according
> + * to the parent EEH device.
> + */
> +static struct eeh_pe *pseries_eeh_pe_get_parent(struct eeh_dev *edev)
> +{
> +	struct eeh_dev *parent;
> +	struct pci_dn *pdn = eeh_dev_to_pdn(edev);
> +
> +	/*
> +	 * It might have the case for the indirect parent
> +	 * EEH device already having associated PE, but
> +	 * the direct parent EEH device doesn't have yet.
> +	 */
> +	if (edev->physfn)
> +		pdn = pci_get_pdn(edev->physfn);
> +	else
> +		pdn = pdn ? pdn->parent : NULL;
> +	while (pdn) {
> +		/* We're poking out of PCI territory */
> +		parent = pdn_to_eeh_dev(pdn);
> +		if (!parent)
> +			return NULL;
> +
> +		if (parent->pe)
> +			return parent->pe;
> +
> +		pdn = pdn->parent;
> +	}
> +
> +	return NULL;
> +}
> +
>  /**
>   * pseries_eeh_probe - EEH probe on the given device
>   * @pdn: PCI device node
> @@ -286,10 +324,14 @@ static void pseries_eeh_probe_pdn(struct pci_dn *pdn)
>  	if (ret) {
>  		eeh_edev_dbg(edev, "EEH failed to enable on device (code %d)\n", ret);
>  	} else {
> +		struct eeh_pe *parent;
> +
>  		/* Retrieve PE address */
>  		edev->pe_config_addr = eeh_ops->get_pe_addr(&pe);
>  		pe.addr = edev->pe_config_addr;
>  
> +		parent = pseries_eeh_pe_get_parent(edev);
> +
>  		/* Some older systems (Power4) allow the ibm,set-eeh-option
>  		 * call to succeed even on nodes where EEH is not supported.
>  		 * Verify support explicitly.
> @@ -298,16 +340,15 @@ static void pseries_eeh_probe_pdn(struct pci_dn *pdn)
>  		if (ret > 0 && ret != EEH_STATE_NOT_SUPPORT)
>  			enable = 1;
>  
> -		if (enable) {
> +		/* This device doesn't support EEH, but it may have an
> +		 * EEH parent, in which case we mark it as supported.
> +		 */
> +		if (parent && !enable)
> +			edev->pe_config_addr = parent->addr;
> +
> +		if (enable || parent) {
>  			eeh_add_flag(EEH_ENABLED);
> -			eeh_add_to_parent_pe(edev);
> -		} else if (pdn->parent && pdn_to_eeh_dev(pdn->parent) &&
> -			   (pdn_to_eeh_dev(pdn->parent))->pe) {
> -			/* This device doesn't support EEH, but it may have an
> -			 * EEH parent, in which case we mark it as supported.
> -			 */
> -			edev->pe_config_addr = pdn_to_eeh_dev(pdn->parent)->pe_config_addr;
> -			eeh_add_to_parent_pe(edev);
> +			eeh_add_to_parent_pe(parent, edev);
>  		}
>  		eeh_edev_dbg(edev, "EEH is %s on device (code %d)\n",
>  			     (enable ? "enabled" : "unsupported"), ret);
> 

-- 
Alexey