Re: [PATCH v6 06/11] powerpc/pseries/iommu: Add ddw_property_create() and refactor enable_ddw()

[Frederic Barrat]

On 17/08/2021 08:39, Leonardo Bras wrote:
> Code used to create a ddw property that was previously scattered in
> enable_ddw() is now gathered in ddw_property_create(), which deals with
> allocation and filling the property, letting it ready for
> of_property_add(), which now occurs in sequence.
>
> This created an opportunity to reorganize the second part of enable_ddw():
>
> Without this patch enable_ddw() does, in order:
> kzalloc() property & members, create_ddw(), fill ddwprop inside property,
> ddw_list_new_entry(), do tce_setrange_multi_pSeriesLP_walk in all memory,
> of_add_property(), and list_add().
>
> With this patch enable_ddw() does, in order:
> create_ddw(), ddw_property_create(), of_add_property(),
> ddw_list_new_entry(), do tce_setrange_multi_pSeriesLP_walk in all memory,
> and list_add().
>
> This change requires of_remove_property() in case anything fails after
> of_add_property(), but we get to do tce_setrange_multi_pSeriesLP_walk
> in all memory, which looks the most expensive operation, only if
> everything else succeeds.
>
> Also, the error path got remove_ddw() replaced by a new helper
> __remove_dma_window(), which only removes the new DDW with an rtas-call.
> For this, a new helper clean_dma_window() was needed to clean anything
> that could left if walk_system_ram_range() fails.
>
> Signed-off-by: Leonardo Bras <leobras.c@xxxxxxxxx>
> Reviewed-by: Alexey Kardashevskiy <aik@xxxxxxxxx>
> ---


Thanks for fixing the error paths
Reviewed-by: Frederic Barrat <fbarrat@xxxxxxxxxxxxx>


>   arch/powerpc/platforms/pseries/iommu.c | 129 ++++++++++++++++---------
>   1 file changed, 84 insertions(+), 45 deletions(-)
>
> diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
> index b34b473bbdc1..00392582fe10 100644
> --- a/arch/powerpc/platforms/pseries/iommu.c
> +++ b/arch/powerpc/platforms/pseries/iommu.c
> @@ -795,17 +795,10 @@ static int __init disable_ddw_setup(char *str)
>   
>   early_param("disable_ddw", disable_ddw_setup);
>   
> -static void remove_dma_window(struct device_node *np, u32 *ddw_avail,
> -			      struct property *win)
> +static void clean_dma_window(struct device_node *np, struct dynamic_dma_window_prop *dwp)
>   {
> -	struct dynamic_dma_window_prop *dwp;
> -	u64 liobn;
>   	int ret;
>   
> -	dwp = win->value;
> -	liobn = (u64)be32_to_cpu(dwp->liobn);
> -
> -	/* clear the whole window, note the arg is in kernel pages */
>   	ret = tce_clearrange_multi_pSeriesLP(0,
>   		1ULL << (be32_to_cpu(dwp->window_shift) - PAGE_SHIFT), dwp);
>   	if (ret)
> @@ -814,18 +807,39 @@ static void remove_dma_window(struct device_node *np, u32 *ddw_avail,
>   	else
>   		pr_debug("%pOF successfully cleared tces in window.\n",
>   			 np);
> +}
> +
> +/*
> + * Call only if DMA window is clean.
> + */
> +static void __remove_dma_window(struct device_node *np, u32 *ddw_avail, u64 liobn)
> +{
> +	int ret;
>   
>   	ret = rtas_call(ddw_avail[DDW_REMOVE_PE_DMA_WIN], 1, 1, NULL, liobn);
>   	if (ret)
> -		pr_warn("%pOF: failed to remove direct window: rtas returned "
> +		pr_warn("%pOF: failed to remove DMA window: rtas returned "
>   			"%d to ibm,remove-pe-dma-window(%x) %llx\n",
>   			np, ret, ddw_avail[DDW_REMOVE_PE_DMA_WIN], liobn);
>   	else
> -		pr_debug("%pOF: successfully removed direct window: rtas returned "
> +		pr_debug("%pOF: successfully removed DMA window: rtas returned "
>   			"%d to ibm,remove-pe-dma-window(%x) %llx\n",
>   			np, ret, ddw_avail[DDW_REMOVE_PE_DMA_WIN], liobn);
>   }
>   
> +static void remove_dma_window(struct device_node *np, u32 *ddw_avail,
> +			      struct property *win)
> +{
> +	struct dynamic_dma_window_prop *dwp;
> +	u64 liobn;
> +
> +	dwp = win->value;
> +	liobn = (u64)be32_to_cpu(dwp->liobn);
> +
> +	clean_dma_window(np, dwp);
> +	__remove_dma_window(np, ddw_avail, liobn);
> +}
> +
>   static void remove_ddw(struct device_node *np, bool remove_prop)
>   {
>   	struct property *win;
> @@ -1153,6 +1167,35 @@ static int iommu_get_page_shift(u32 query_page_size)
>   	return 0;
>   }
>   
> +static struct property *ddw_property_create(const char *propname, u32 liobn, u64 dma_addr,
> +					    u32 page_shift, u32 window_shift)
> +{
> +	struct dynamic_dma_window_prop *ddwprop;
> +	struct property *win64;
> +
> +	win64 = kzalloc(sizeof(*win64), GFP_KERNEL);
> +	if (!win64)
> +		return NULL;
> +
> +	win64->name = kstrdup(propname, GFP_KERNEL);
> +	ddwprop = kzalloc(sizeof(*ddwprop), GFP_KERNEL);
> +	win64->value = ddwprop;
> +	win64->length = sizeof(*ddwprop);
> +	if (!win64->name || !win64->value) {
> +		kfree(win64->name);
> +		kfree(win64->value);
> +		kfree(win64);
> +		return NULL;
> +	}
> +
> +	ddwprop->liobn = cpu_to_be32(liobn);
> +	ddwprop->dma_base = cpu_to_be64(dma_addr);
> +	ddwprop->tce_shift = cpu_to_be32(page_shift);
> +	ddwprop->window_shift = cpu_to_be32(window_shift);
> +
> +	return win64;
> +}
> +
>   /*
>    * If the PE supports dynamic dma windows, and there is space for a table
>    * that can map all pages in a linear offset, then setup such a table,
> @@ -1171,12 +1214,12 @@ static bool enable_ddw(struct pci_dev *dev, struct device_node *pdn)
>   	struct ddw_query_response query;
>   	struct ddw_create_response create;
>   	int page_shift;
> +	u64 win_addr;
>   	struct device_node *dn;
>   	u32 ddw_avail[DDW_APPLICABLE_SIZE];
>   	struct direct_window *window;
>   	struct property *win64;
>   	bool ddw_enabled = false;
> -	struct dynamic_dma_window_prop *ddwprop;
>   	struct failed_ddw_pdn *fpdn;
>   	bool default_win_removed = false;
>   	bool pmem_present;
> @@ -1293,72 +1336,68 @@ static bool enable_ddw(struct pci_dev *dev, struct device_node *pdn)
>   			1ULL << page_shift);
>   		goto out_failed;
>   	}
> -	win64 = kzalloc(sizeof(struct property), GFP_KERNEL);
> -	if (!win64) {
> -		dev_info(&dev->dev,
> -			"couldn't allocate property for 64bit dma window\n");
> -		goto out_failed;
> -	}
> -	win64->name = kstrdup(DIRECT64_PROPNAME, GFP_KERNEL);
> -	win64->value = ddwprop = kmalloc(sizeof(*ddwprop), GFP_KERNEL);
> -	win64->length = sizeof(*ddwprop);
> -	if (!win64->name || !win64->value) {
> -		dev_info(&dev->dev,
> -			"couldn't allocate property name and value\n");
> -		goto out_free_prop;
> -	}
>   
>   	ret = create_ddw(dev, ddw_avail, &create, page_shift, len);
>   	if (ret != 0)
> -		goto out_free_prop;
> -
> -	ddwprop->liobn = cpu_to_be32(create.liobn);
> -	ddwprop->dma_base = cpu_to_be64(((u64)create.addr_hi << 32) |
> -			create.addr_lo);
> -	ddwprop->tce_shift = cpu_to_be32(page_shift);
> -	ddwprop->window_shift = cpu_to_be32(len);
> +		goto out_failed;
>   
>   	dev_dbg(&dev->dev, "created tce table LIOBN 0x%x for %pOF\n",
>   		  create.liobn, dn);
>   
> -	window = ddw_list_new_entry(pdn, ddwprop);
> +	win_addr = ((u64)create.addr_hi << 32) | create.addr_lo;
> +	win64 = ddw_property_create(DIRECT64_PROPNAME, create.liobn, win_addr,
> +				    page_shift, len);
> +	if (!win64) {
> +		dev_info(&dev->dev,
> +			 "couldn't allocate property, property name, or value\n");
> +		goto out_remove_win;
> +	}
> +
> +	ret = of_add_property(pdn, win64);
> +	if (ret) {
> +		dev_err(&dev->dev, "unable to add dma window property for %pOF: %d",
> +			pdn, ret);
> +		goto out_free_prop;
> +	}
> +
> +	window = ddw_list_new_entry(pdn, win64->value);
>   	if (!window)
> -		goto out_clear_window;
> +		goto out_del_prop;
>   
>   	ret = walk_system_ram_range(0, memblock_end_of_DRAM() >> PAGE_SHIFT,
>   			win64->value, tce_setrange_multi_pSeriesLP_walk);
>   	if (ret) {
>   		dev_info(&dev->dev, "failed to map direct window for %pOF: %d\n",
>   			 dn, ret);
> -		goto out_free_window;
> -	}
>   
> -	ret = of_add_property(pdn, win64);
> -	if (ret) {
> -		dev_err(&dev->dev, "unable to add dma window property for %pOF: %d",
> -			 pdn, ret);
> -		goto out_free_window;
> +		/* Make sure to clean DDW if any TCE was set*/
> +		clean_dma_window(pdn, win64->value);
> +		goto out_del_list;
>   	}
>   
>   	spin_lock(&direct_window_list_lock);
>   	list_add(&window->list, &direct_window_list);
>   	spin_unlock(&direct_window_list_lock);
>   
> -	dev->dev.archdata.dma_offset = be64_to_cpu(ddwprop->dma_base);
> +	dev->dev.archdata.dma_offset = win_addr;
>   	ddw_enabled = true;
>   	goto out_unlock;
>   
> -out_free_window:
> +out_del_list:
>   	kfree(window);
>   
> -out_clear_window:
> -	remove_ddw(pdn, true);
> +out_del_prop:
> +	of_remove_property(pdn, win64);
>   
>   out_free_prop:
>   	kfree(win64->name);
>   	kfree(win64->value);
>   	kfree(win64);
>   
> +out_remove_win:
> +	/* DDW is clean, so it's ok to call this directly. */
> +	__remove_dma_window(pdn, ddw_avail, create.liobn);
> +
>   out_failed:
>   	if (default_win_removed)
>   		reset_dma_window(dev, pdn);