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Subject: Re: [PATCH v5 2/4] powerpc/pseries/iommu: Update call to
 ibm,query-pe-dma-windows
To:     Leonardo Bras <leobras.c@gmail.com>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Thiago Jung Bauermann <bauerman@linux.ibm.com>,
        Ram Pai <linuxram@us.ibm.com>,
        Brian King <brking@linux.vnet.ibm.com>,
        Murilo Fossa Vicentini <muvic@linux.ibm.com>,
        David Dai <zdai@linux.vnet.ibm.com>
Cc:     linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
References: <20200805030455.123024-1-leobras.c@gmail.com>
 <20200805030455.123024-3-leobras.c@gmail.com>
From:   Alexey Kardashevskiy <aik@ozlabs.ru>
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Message-ID: <4767d7e9-1f08-eb64-46a8-f4fc612fe752@ozlabs.ru>
Date:   Wed, 5 Aug 2020 13:16:53 +1000
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On 05/08/2020 13:04, Leonardo Bras wrote:
> From LoPAR level 2.8, "ibm,ddw-extensions" index 3 can make the number of
> outputs from "ibm,query-pe-dma-windows" go from 5 to 6.
> 
> This change of output size is meant to expand the address size of
> largest_available_block PE TCE from 32-bit to 64-bit, which ends up
> shifting page_size and migration_capable.
> 
> This ends up requiring the update of
> ddw_query_response->largest_available_block from u32 to u64, and manually
> assigning the values from the buffer into this struct, according to
> output size.
> 
> Also, a routine was created for helping reading the ddw extensions as
> suggested by LoPAR: First reading the size of the extension array from
> index 0, checking if the property exists, and then returning it's value.
> 
> Signed-off-by: Leonardo Bras <leobras.c@gmail.com>
> Tested-by: David Dai <zdai@linux.vnet.ibm.com>


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


> ---
>  arch/powerpc/platforms/pseries/iommu.c | 91 +++++++++++++++++++++++---
>  1 file changed, 81 insertions(+), 10 deletions(-)
> 
> diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
> index ac0d6376bdad..1a933c4e8bba 100644
> --- a/arch/powerpc/platforms/pseries/iommu.c
> +++ b/arch/powerpc/platforms/pseries/iommu.c
> @@ -47,6 +47,12 @@ enum {
>  	DDW_APPLICABLE_SIZE
>  };
>  
> +enum {
> +	DDW_EXT_SIZE = 0,
> +	DDW_EXT_RESET_DMA_WIN = 1,
> +	DDW_EXT_QUERY_OUT_SIZE = 2
> +};
> +
>  static struct iommu_table_group *iommu_pseries_alloc_group(int node)
>  {
>  	struct iommu_table_group *table_group;
> @@ -342,7 +348,7 @@ struct direct_window {
>  /* Dynamic DMA Window support */
>  struct ddw_query_response {
>  	u32 windows_available;
> -	u32 largest_available_block;
> +	u64 largest_available_block;
>  	u32 page_size;
>  	u32 migration_capable;
>  };
> @@ -877,14 +883,62 @@ static int find_existing_ddw_windows(void)
>  }
>  machine_arch_initcall(pseries, find_existing_ddw_windows);
>  
> +/**
> + * ddw_read_ext - Get the value of an DDW extension
> + * @np:		device node from which the extension value is to be read.
> + * @extnum:	index number of the extension.
> + * @value:	pointer to return value, modified when extension is available.
> + *
> + * Checks if "ibm,ddw-extensions" exists for this node, and get the value
> + * on index 'extnum'.
> + * It can be used only to check if a property exists, passing value == NULL.
> + *
> + * Returns:
> + *	0 if extension successfully read
> + *	-EINVAL if the "ibm,ddw-extensions" does not exist,
> + *	-ENODATA if "ibm,ddw-extensions" does not have a value, and
> + *	-EOVERFLOW if "ibm,ddw-extensions" does not contain this extension.
> + */
> +static inline int ddw_read_ext(const struct device_node *np, int extnum,
> +			       u32 *value)
> +{
> +	static const char propname[] = "ibm,ddw-extensions";
> +	u32 count;
> +	int ret;
> +
> +	ret = of_property_read_u32_index(np, propname, DDW_EXT_SIZE, &count);
> +	if (ret)
> +		return ret;
> +
> +	if (count < extnum)
> +		return -EOVERFLOW;
> +
> +	if (!value)
> +		value = &count;
> +
> +	return of_property_read_u32_index(np, propname, extnum, value);
> +}
> +
>  static int query_ddw(struct pci_dev *dev, const u32 *ddw_avail,
> -			struct ddw_query_response *query)
> +		     struct ddw_query_response *query,
> +		     struct device_node *parent)
>  {
>  	struct device_node *dn;
>  	struct pci_dn *pdn;
> -	u32 cfg_addr;
> +	u32 cfg_addr, ext_query, query_out[5];
>  	u64 buid;
> -	int ret;
> +	int ret, out_sz;
> +
> +	/*
> +	 * From LoPAR level 2.8, "ibm,ddw-extensions" index 3 can rule how many
> +	 * output parameters ibm,query-pe-dma-windows will have, ranging from
> +	 * 5 to 6.
> +	 */
> +	ret = ddw_read_ext(parent, DDW_EXT_QUERY_OUT_SIZE, &ext_query);
> +	if (!ret && ext_query == 1)
> +		out_sz = 6;
> +	else
> +		out_sz = 5;
>  
>  	/*
>  	 * Get the config address and phb buid of the PE window.
> @@ -897,11 +951,28 @@ static int query_ddw(struct pci_dev *dev, const u32 *ddw_avail,
>  	buid = pdn->phb->buid;
>  	cfg_addr = ((pdn->busno << 16) | (pdn->devfn << 8));
>  
> -	ret = rtas_call(ddw_avail[DDW_QUERY_PE_DMA_WIN], 3, 5, (u32 *)query,
> +	ret = rtas_call(ddw_avail[DDW_QUERY_PE_DMA_WIN], 3, out_sz, query_out,
>  			cfg_addr, BUID_HI(buid), BUID_LO(buid));
> -	dev_info(&dev->dev, "ibm,query-pe-dma-windows(%x) %x %x %x"
> -		" returned %d\n", ddw_avail[DDW_QUERY_PE_DMA_WIN], cfg_addr,
> -		 BUID_HI(buid), BUID_LO(buid), ret);
> +	dev_info(&dev->dev, "ibm,query-pe-dma-windows(%x) %x %x %x returned %d\n",
> +		 ddw_avail[DDW_QUERY_PE_DMA_WIN], cfg_addr, BUID_HI(buid),
> +		 BUID_LO(buid), ret);
> +
> +	switch (out_sz) {
> +	case 5:
> +		query->windows_available = query_out[0];
> +		query->largest_available_block = query_out[1];
> +		query->page_size = query_out[2];
> +		query->migration_capable = query_out[3];
> +		break;
> +	case 6:
> +		query->windows_available = query_out[0];
> +		query->largest_available_block = ((u64)query_out[1] << 32) |
> +						 query_out[2];
> +		query->page_size = query_out[3];
> +		query->migration_capable = query_out[4];
> +		break;
> +	}
> +
>  	return ret;
>  }
>  
> @@ -1049,7 +1120,7 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn)
>  	 * of page sizes: supported and supported for migrate-dma.
>  	 */
>  	dn = pci_device_to_OF_node(dev);
> -	ret = query_ddw(dev, ddw_avail, &query);
> +	ret = query_ddw(dev, ddw_avail, &query, pdn);
>  	if (ret != 0)
>  		goto out_failed;
>  
> @@ -1077,7 +1148,7 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn)
>  	/* check largest block * page size > max memory hotplug addr */
>  	max_addr = ddw_memory_hotplug_max();
>  	if (query.largest_available_block < (max_addr >> page_shift)) {
> -		dev_dbg(&dev->dev, "can't map partition max 0x%llx with %u "
> +		dev_dbg(&dev->dev, "can't map partition max 0x%llx with %llu "
>  			  "%llu-sized pages\n", max_addr,  query.largest_available_block,
>  			  1ULL << page_shift);
>  		goto out_failed;
> 

-- 
Alexey