linux-kernel - Re: [PATCH 2/4] powerpc/pseries/iommu: Implement ibm,reset-pe-dma-windows rtas call

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Message-ID: <2f004ecc-4788-47b6-e9ae-0c08d4723008@ozlabs.ru>
Date:   Mon, 22 Jun 2020 20:02:22 +1000
From:   Alexey Kardashevskiy <aik@...abs.ru>
To:     Leonardo Bras <leobras.c@...il.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Thiago Jung Bauermann <bauerman@...ux.ibm.com>,
        Ram Pai <linuxram@...ibm.com>
Cc:     linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/4] powerpc/pseries/iommu: Implement
 ibm,reset-pe-dma-windows rtas call



On 19/06/2020 15:06, Leonardo Bras wrote:
> Platforms supporting the DDW option starting with LoPAR level 2.7 implement
> ibm,ddw-extensions. The first extension available (index 2) carries the
> token for ibm,reset-pe-dma-windows rtas call, which is used to restore
> the default DMA window for a device, if it has been deleted.
> 
> It does so by resetting the TCE table allocation for the PE to it's
> boot time value, available in "ibm,dma-window" device tree node.
> 
> Signed-off-by: Leonardo Bras <leobras.c@...il.com>
> ---
>  arch/powerpc/platforms/pseries/iommu.c | 33 ++++++++++++++++++++++++++
>  1 file changed, 33 insertions(+)
> 
> diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
> index e5a617738c8b..5e1fbc176a37 100644
> --- a/arch/powerpc/platforms/pseries/iommu.c
> +++ b/arch/powerpc/platforms/pseries/iommu.c
> @@ -1012,6 +1012,39 @@ static phys_addr_t ddw_memory_hotplug_max(void)
>  	return max_addr;
>  }
>  
> +/*
> + * Platforms supporting the DDW option starting with LoPAR level 2.7 implement
> + * ibm,ddw-extensions, which carries the rtas token for
> + * ibm,reset-pe-dma-windows.
> + * That rtas-call can be used to restore the default DMA window for the device.
> + */
> +static void reset_dma_window(struct pci_dev *dev, struct device_node *par_dn)
> +{
> +	int ret;
> +	u32 cfg_addr, ddw_ext[3];
> +	u64 buid;
> +	struct device_node *dn;
> +	struct pci_dn *pdn;
> +
> +	ret = of_property_read_u32_array(par_dn, "ibm,ddw-extensions",
> +					 &ddw_ext[0], 3);

s/3/2/ as for the reset extension you do not need the "64bit largest
block" extension.


> +	if (ret)
> +		return;
> +
> +	dn = pci_device_to_OF_node(dev);
> +	pdn = PCI_DN(dn);
> +	buid = pdn->phb->buid;
> +	cfg_addr = ((pdn->busno << 16) | (pdn->devfn << 8));
> +
> +	ret = rtas_call(ddw_ext[1], 3, 1, NULL, cfg_addr,


Here the "reset" extention is in ddw_ext[1]. Hm. 1/4 has a bug then.

And I am pretty sure it won't compile as reset_dma_window() is not used
and it is static so fold it into one the next patches. Thanks,


> +			BUID_HI(buid), BUID_LO(buid));
> +	if (ret)
> +		dev_info(&dev->dev,
> +			 "ibm,reset-pe-dma-windows(%x) %x %x %x returned %d ",
> +			 ddw_ext[1], cfg_addr, BUID_HI(buid), BUID_LO(buid),
> +			 ret);
> +}
> +
>  /*
>   * 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,
> 

-- 
Alexey