Re: [PATCH 1/4] powerpc/pseries/iommu: Update call to ibm,query-pe-dma-windows

[Alexey Kardashevskiy]

On 19/06/2020 15:06, 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.
> 
> Signed-off-by: Leonardo Bras <leobras.c@xxxxxxxxx>
> ---
>  arch/powerpc/platforms/pseries/iommu.c | 57 +++++++++++++++++++++-----
>  1 file changed, 46 insertions(+), 11 deletions(-)
> 
> diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
> index 6d47b4a3ce39..e5a617738c8b 100644
> --- a/arch/powerpc/platforms/pseries/iommu.c
> +++ b/arch/powerpc/platforms/pseries/iommu.c
> @@ -334,7 +334,7 @@ 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;
>  };
> @@ -869,14 +869,32 @@ static int find_existing_ddw_windows(void)
>  }
>  machine_arch_initcall(pseries, find_existing_ddw_windows);
>  
> +/*
> + * 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.
> + */
> +
> +static int query_ddw_out_sz(struct device_node *par_dn)

Can easily be folded into query_ddw().

> +{
> +	int ret;
> +	u32 ddw_ext[3];
> +
> +	ret = of_property_read_u32_array(par_dn, "ibm,ddw-extensions",
> +					 &ddw_ext[0], 3);
> +	if (ret || ddw_ext[0] < 2 || ddw_ext[2] != 1)


Oh that PAPR thing again :-/

===
The âibm,ddw-extensionsâ property value is a list of integers the first
integer indicates the number of extensions implemented and subsequent
integers, one per extension, provide a value associated with that
extension.
===

So ddw_ext[0] is length.
Listindex==2 is for "reset" says PAPR and
Listindex==3 is for this new 64bit "largest_available_block".

So I'd expect ddw_ext[2] to have the "reset" token and ddw_ext[3] to
have "1" for this new feature but indexes are smaller. I am confused.
Either way these "2" and "3" needs to be defined in macros, "0" probably
too.

Please post 'lsprop "ibm,ddw-extensions"' here. Thanks,



> +		return 5;
> +	return 6;
> +}
> +
>  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 *par_dn)
>  {
>  	struct device_node *dn;
>  	struct pci_dn *pdn;
> -	u32 cfg_addr;
> +	u32 cfg_addr, query_out[5];
>  	u64 buid;
> -	int ret;
> +	int ret, out_sz;
>  
>  	/*
>  	 * Get the config address and phb buid of the PE window.
> @@ -888,12 +906,29 @@ static int query_ddw(struct pci_dev *dev, const u32 *ddw_avail,
>  	pdn = PCI_DN(dn);
>  	buid = pdn->phb->buid;
>  	cfg_addr = ((pdn->busno << 16) | (pdn->devfn << 8));
> +	out_sz = query_ddw_out_sz(par_dn);
> +
> +	ret = rtas_call(ddw_avail[0], 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[0], 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;
> +	}
>  
> -	ret = rtas_call(ddw_avail[0], 3, 5, (u32 *)query,
> -		  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[0], cfg_addr, BUID_HI(buid),
> -		BUID_LO(buid), ret);
>  	return ret;
>  }
>  
> @@ -1040,7 +1075,7 @@ 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;
>  
> @@ -1068,7 +1103,7 @@ 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