Re: [PATCH v12 14/21] powerpc/powernv: Allocate struct pnv_ioda_pe iommu_table dynamically

[Bjorn Helgaas <bhelgaas@google.com>]

On Tue, Feb 24, 2015 at 02:34:35AM -0600, Bjorn Helgaas wrote:
> From: Wei Yang <weiyang@linux.vnet.ibm.com>
> 
> Current iommu_table of a PE is a static field.  This will have a problem
> when iommu_free_table() is called.
> 
> Allocate iommu_table dynamically.

I'd like a little more explanation about why we're calling
iommu_free_table() now when we didn't call it before.  Maybe this happens
when we disable SR-IOV and the VFs go away?

Is there a hotplug remove path where we should also be calling
iommu_free_table()?

> Signed-off-by: Wei Yang <weiyang@linux.vnet.ibm.com>
> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
> ---
>  arch/powerpc/include/asm/iommu.h          |    3 +++
>  arch/powerpc/platforms/powernv/pci-ioda.c |   26 ++++++++++++++------------
>  arch/powerpc/platforms/powernv/pci.h      |    2 +-
>  3 files changed, 18 insertions(+), 13 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/iommu.h b/arch/powerpc/include/asm/iommu.h
> index 9cfa3706a1b8..5574eeb97634 100644
> --- a/arch/powerpc/include/asm/iommu.h
> +++ b/arch/powerpc/include/asm/iommu.h
> @@ -78,6 +78,9 @@ struct iommu_table {
>  	struct iommu_group *it_group;
>  #endif
>  	void (*set_bypass)(struct iommu_table *tbl, bool enable);
> +#ifdef CONFIG_PPC_POWERNV
> +	void           *data;
> +#endif
>  };
>  
>  /* Pure 2^n version of get_order */
> diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
> index 58c4fc4ab63c..cd1a56160ded 100644
> --- a/arch/powerpc/platforms/powernv/pci-ioda.c
> +++ b/arch/powerpc/platforms/powernv/pci-ioda.c
> @@ -916,6 +916,10 @@ static void pnv_ioda_setup_bus_PE(struct pci_bus *bus, int all)
>  		return;
>  	}
>  
> +	pe->tce32_table = kzalloc_node(sizeof(struct iommu_table),
> +			GFP_KERNEL, hose->node);
> +	pe->tce32_table->data = pe;
> +
>  	/* Associate it with all child devices */
>  	pnv_ioda_setup_same_PE(bus, pe);
>  
> @@ -1005,7 +1009,7 @@ static void pnv_pci_ioda_dma_dev_setup(struct pnv_phb *phb, struct pci_dev *pdev
>  
>  	pe = &phb->ioda.pe_array[pdn->pe_number];
>  	WARN_ON(get_dma_ops(&pdev->dev) != &dma_iommu_ops);
> -	set_iommu_table_base_and_group(&pdev->dev, &pe->tce32_table);
> +	set_iommu_table_base_and_group(&pdev->dev, pe->tce32_table);
>  }
>  
>  static int pnv_pci_ioda_dma_set_mask(struct pnv_phb *phb,
> @@ -1032,7 +1036,7 @@ static int pnv_pci_ioda_dma_set_mask(struct pnv_phb *phb,
>  	} else {
>  		dev_info(&pdev->dev, "Using 32-bit DMA via iommu\n");
>  		set_dma_ops(&pdev->dev, &dma_iommu_ops);
> -		set_iommu_table_base(&pdev->dev, &pe->tce32_table);
> +		set_iommu_table_base(&pdev->dev, pe->tce32_table);
>  	}
>  	*pdev->dev.dma_mask = dma_mask;
>  	return 0;
> @@ -1069,9 +1073,9 @@ static void pnv_ioda_setup_bus_dma(struct pnv_ioda_pe *pe,
>  	list_for_each_entry(dev, &bus->devices, bus_list) {
>  		if (add_to_iommu_group)
>  			set_iommu_table_base_and_group(&dev->dev,
> -						       &pe->tce32_table);
> +						       pe->tce32_table);
>  		else
> -			set_iommu_table_base(&dev->dev, &pe->tce32_table);
> +			set_iommu_table_base(&dev->dev, pe->tce32_table);
>  
>  		if (dev->subordinate)
>  			pnv_ioda_setup_bus_dma(pe, dev->subordinate,
> @@ -1161,8 +1165,7 @@ static void pnv_pci_ioda2_tce_invalidate(struct pnv_ioda_pe *pe,
>  void pnv_pci_ioda_tce_invalidate(struct iommu_table *tbl,
>  				 __be64 *startp, __be64 *endp, bool rm)
>  {
> -	struct pnv_ioda_pe *pe = container_of(tbl, struct pnv_ioda_pe,
> -					      tce32_table);
> +	struct pnv_ioda_pe *pe = tbl->data;
>  	struct pnv_phb *phb = pe->phb;
>  
>  	if (phb->type == PNV_PHB_IODA1)
> @@ -1228,7 +1231,7 @@ static void pnv_pci_ioda_setup_dma_pe(struct pnv_phb *phb,
>  	}
>  
>  	/* Setup linux iommu table */
> -	tbl = &pe->tce32_table;
> +	tbl = pe->tce32_table;
>  	pnv_pci_setup_iommu_table(tbl, addr, TCE32_TABLE_SIZE * segs,
>  				  base << 28, IOMMU_PAGE_SHIFT_4K);
>  
> @@ -1266,8 +1269,7 @@ static void pnv_pci_ioda_setup_dma_pe(struct pnv_phb *phb,
>  
>  static void pnv_pci_ioda2_set_bypass(struct iommu_table *tbl, bool enable)
>  {
> -	struct pnv_ioda_pe *pe = container_of(tbl, struct pnv_ioda_pe,
> -					      tce32_table);
> +	struct pnv_ioda_pe *pe = tbl->data;
>  	uint16_t window_id = (pe->pe_number << 1 ) + 1;
>  	int64_t rc;
>  
> @@ -1312,10 +1314,10 @@ static void pnv_pci_ioda2_setup_bypass_pe(struct pnv_phb *phb,
>  	pe->tce_bypass_base = 1ull << 59;
>  
>  	/* Install set_bypass callback for VFIO */
> -	pe->tce32_table.set_bypass = pnv_pci_ioda2_set_bypass;
> +	pe->tce32_table->set_bypass = pnv_pci_ioda2_set_bypass;
>  
>  	/* Enable bypass by default */
> -	pnv_pci_ioda2_set_bypass(&pe->tce32_table, true);
> +	pnv_pci_ioda2_set_bypass(pe->tce32_table, true);
>  }
>  
>  static void pnv_pci_ioda2_setup_dma_pe(struct pnv_phb *phb,
> @@ -1363,7 +1365,7 @@ static void pnv_pci_ioda2_setup_dma_pe(struct pnv_phb *phb,
>  	}
>  
>  	/* Setup linux iommu table */
> -	tbl = &pe->tce32_table;
> +	tbl = pe->tce32_table;
>  	pnv_pci_setup_iommu_table(tbl, addr, tce_table_size, 0,
>  			IOMMU_PAGE_SHIFT_4K);
>  
> diff --git a/arch/powerpc/platforms/powernv/pci.h b/arch/powerpc/platforms/powernv/pci.h
> index e5b75b298d95..731777734bca 100644
> --- a/arch/powerpc/platforms/powernv/pci.h
> +++ b/arch/powerpc/platforms/powernv/pci.h
> @@ -53,7 +53,7 @@ struct pnv_ioda_pe {
>  	/* "Base" iommu table, ie, 4K TCEs, 32-bit DMA */
>  	int			tce32_seg;
>  	int			tce32_segcount;
> -	struct iommu_table	tce32_table;
> +	struct iommu_table	*tce32_table;
>  	phys_addr_t		tce_inval_reg_phys;
>  
>  	/* 64-bit TCE bypass region */
>