Re: [PATCH kernel 3/5] powerpc/powernv: Detach npu struct from pnv_phb

[David Gibson <david@gibson.dropbear.id.au>]

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On Mon, Oct 15, 2018 at 08:32:59PM +1100, Alexey Kardashevskiy wrote:
> The powernv PCI code stores NPU data in the pnv_phb struct. The latter
> is referenced by pci_controller::private_data. We are going to have NPU2
> support in the pseries platform as well but it does not store any
> private_data in in the pci_controller struct; and even if it did,
> it would be a different data structure.
> 
> This adds a global list of NPUs so each platform can register and use
> these in the same fashion.
> 
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> ---
>  arch/powerpc/platforms/powernv/pci.h     | 16 -------
>  arch/powerpc/platforms/powernv/npu-dma.c | 71 +++++++++++++++++++++++++-------
>  2 files changed, 57 insertions(+), 30 deletions(-)
> 
> diff --git a/arch/powerpc/platforms/powernv/pci.h b/arch/powerpc/platforms/powernv/pci.h
> index 8b37b28..3b7617d 100644
> --- a/arch/powerpc/platforms/powernv/pci.h
> +++ b/arch/powerpc/platforms/powernv/pci.h
> @@ -8,9 +8,6 @@
>  
>  struct pci_dn;
>  
> -/* Maximum possible number of ATSD MMIO registers per NPU */
> -#define NV_NMMU_ATSD_REGS 8
> -
>  enum pnv_phb_type {
>  	PNV_PHB_IODA1		= 0,
>  	PNV_PHB_IODA2		= 1,
> @@ -180,19 +177,6 @@ struct pnv_phb {
>  	unsigned int		diag_data_size;
>  	u8			*diag_data;
>  
> -	/* Nvlink2 data */
> -	struct npu {
> -		int index;
> -		__be64 *mmio_atsd_regs[NV_NMMU_ATSD_REGS];
> -		unsigned int mmio_atsd_count;
> -
> -		/* Bitmask for MMIO register usage */
> -		unsigned long mmio_atsd_usage;
> -
> -		/* Do we need to explicitly flush the nest mmu? */
> -		bool nmmu_flush;
> -	} npu;
> -
>  	int p2p_target_count;
>  };
>  
> diff --git a/arch/powerpc/platforms/powernv/npu-dma.c b/arch/powerpc/platforms/powernv/npu-dma.c
> index 01402f9..cb2b4f9 100644
> --- a/arch/powerpc/platforms/powernv/npu-dma.c
> +++ b/arch/powerpc/platforms/powernv/npu-dma.c
> @@ -378,6 +378,25 @@ struct pnv_ioda_pe *pnv_pci_npu_setup_iommu(struct pnv_ioda_pe *npe)
>  /*
>   * NPU2 ATS
>   */
> +/* Maximum possible number of ATSD MMIO registers per NPU */
> +#define NV_NMMU_ATSD_REGS 8
> +
> +struct npu {
> +	int index;
> +	__be64 *mmio_atsd_regs[NV_NMMU_ATSD_REGS];
> +	unsigned int mmio_atsd_count;
> +
> +	/* Bitmask for MMIO register usage */
> +	unsigned long mmio_atsd_usage;
> +
> +	/* Do we need to explicitly flush the nest mmu? */
> +	bool nmmu_flush;
> +
> +	struct list_head next;
> +
> +	struct pci_controller *hose;
> +};
> +
>  static struct {
>  	/*
>  	 * spinlock to protect initialisation of an npu_context for
> @@ -396,22 +415,27 @@ static struct {
>  	uint64_t atsd_threshold;
>  	struct dentry *atsd_threshold_dentry;
>  
> +	struct list_head npu_list;
>  } npu2_devices;
>  
>  void pnv_npu2_devices_init(void)
>  {
>  	memset(&npu2_devices, 0, sizeof(npu2_devices));
> +	INIT_LIST_HEAD(&npu2_devices.npu_list);
>  	spin_lock_init(&npu2_devices.context_lock);
>  	npu2_devices.atsd_threshold = 2 * 1024 * 1024;
>  }
>  
>  static struct npu *npdev_to_npu(struct pci_dev *npdev)
>  {
> -	struct pnv_phb *nphb;
> +	struct pci_controller *hose = pci_bus_to_host(npdev->bus);
> +	struct npu *npu;
>  
> -	nphb = pci_bus_to_host(npdev->bus)->private_data;
> +	list_for_each_entry(npu, &npu2_devices.npu_list, next)
> +		if (hose == npu->hose)
> +			return npu;
>  
> -	return &nphb->npu;
> +	return NULL;

If you're introducing the possibility this can fail, should you also
be introducing checks for NULL in the callers?

>  }
>  
>  /* Maximum number of nvlinks per npu */
> @@ -843,7 +867,7 @@ struct npu_context *pnv_npu2_init_context(struct pci_dev *gpdev,
>  	 */
>  	WRITE_ONCE(npu_context->npdev[npu->index][nvlink_index], npdev);
>  
> -	if (!nphb->npu.nmmu_flush) {
> +	if (!npu->nmmu_flush) {

Looks like this hunk belongs in the patch which introduced npdev_to_npu().

>  		/*
>  		 * If we're not explicitly flushing ourselves we need to mark
>  		 * the thread for global flushes
> @@ -967,6 +991,13 @@ int pnv_npu2_init(struct pnv_phb *phb)
>  	struct pci_dev *gpdev;
>  	static int npu_index;
>  	uint64_t rc = 0;
> +	struct pci_controller *hose = phb->hose;
> +	struct npu *npu;
> +	int ret;
> +
> +	npu = kzalloc(sizeof(*npu), GFP_KERNEL);
> +	if (!npu)
> +		return -ENOMEM;
>  
>  	if (!npu2_devices.atsd_threshold_dentry) {
>  		npu2_devices.atsd_threshold_dentry = debugfs_create_x64(
> @@ -974,8 +1005,7 @@ int pnv_npu2_init(struct pnv_phb *phb)
>  				&npu2_devices.atsd_threshold);
>  	}
>  
> -	phb->npu.nmmu_flush =
> -		of_property_read_bool(phb->hose->dn, "ibm,nmmu-flush");
> +	npu->nmmu_flush = of_property_read_bool(hose->dn, "ibm,nmmu-flush");
>  	for_each_child_of_node(phb->hose->dn, dn) {
>  		gpdev = pnv_pci_get_gpu_dev(get_pci_dev(dn));
>  		if (gpdev) {
> @@ -989,18 +1019,31 @@ int pnv_npu2_init(struct pnv_phb *phb)
>  		}
>  	}
>  
> -	for (i = 0; !of_property_read_u64_index(phb->hose->dn, "ibm,mmio-atsd",
> +	for (i = 0; !of_property_read_u64_index(hose->dn, "ibm,mmio-atsd",
>  							i, &mmio_atsd); i++)
> -		phb->npu.mmio_atsd_regs[i] = ioremap(mmio_atsd, 32);
> +		npu->mmio_atsd_regs[i] = ioremap(mmio_atsd, 32);
>  
> -	pr_info("NPU%lld: Found %d MMIO ATSD registers", phb->opal_id, i);
> -	phb->npu.mmio_atsd_count = i;
> -	phb->npu.mmio_atsd_usage = 0;
> +	pr_info("NPU%d: Found %d MMIO ATSD registers", hose->global_number, i);
> +	npu->mmio_atsd_count = i;
> +	npu->mmio_atsd_usage = 0;
>  	npu_index++;
> -	if (WARN_ON(npu_index >= NV_MAX_NPUS))
> -		return -ENOSPC;
> +	if (WARN_ON(npu_index >= NV_MAX_NPUS)) {
> +		ret = -ENOSPC;
> +		goto fail_exit;
> +	}
>  	npu2_devices.max_index = npu_index;
> -	phb->npu.index = npu_index;
> +	npu->index = npu_index;
> +	npu->hose = hose;
> +
> +	list_add(&npu->next, &npu2_devices.npu_list);
>  
>  	return 0;
> +
> +fail_exit:
> +	for (i = 0; i < npu->mmio_atsd_count; ++i)
> +		iounmap(npu->mmio_atsd_regs[i]);
> +
> +	kfree(npu);
> +
> +	return ret;
>  }

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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