Re: [PATCH 1/3] of/pci/dma: fix DMA configuration for PCI masters

Re: [PATCH 1/3] of/pci/dma: fix DMA configuration for PCI masters

[Rob Herring]

On Tue, May 2, 2017 at 11:46 PM, Oza Pawandeep <oza.oza@broadcom.com> wrote:
> current device framework and of framework integration assumes
> dma-ranges in a way where memory-mapped devices define their
> dma-ranges. (child-bus-address, parent-bus-address, length).
>
> of_dma_configure is specifically written to take care of memory
> mapped devices. but no implementation exists for pci to take
> care of pcie based memory ranges.
>
> for e.g. iproc based SOCs and other SOCs(suc as rcar) have PCI
> world dma-ranges.
> dma-ranges = <0x43000000 0x00 0x00 0x00 0x00 0x80 0x00>;
>
> this patch serves following:
>
> 1) exposes interface to the pci host driver for their
> inbound memory ranges
>
> 2) provide an interface to callers such as of_dma_get_ranges.
> so then the returned size get best possible (largest) dma_mask.
> because PCI RC drivers do not call APIs such as
> dma_set_coherent_mask() and hence rather it shows its addressing
> capabilities based on dma-ranges.
> for e.g.
> dma-ranges = <0x43000000 0x00 0x00 0x00 0x00 0x80 0x00>;
> we should get dev->coherent_dma_mask=0x7fffffffff.
>
> 3) this patch handles multiple inbound windows and dma-ranges.
> it is left to the caller, how it wants to use them.
> the new function returns the resources in a standard and unform way
>
> 4) this way the callers of for e.g. of_dma_get_ranges
> does not need to change.
>
> 5) leaves scope of adding PCI flag handling for inbound memory
> by the new function.
>
> Bug: SOC-5216
> Change-Id: Ie045386df91e1e0587846bb147ae40d96f6d7d2e
> Signed-off-by: Oza Pawandeep <oza.oza@broadcom.com>
> Reviewed-on: http://gerrit-ccxsw.broadcom.net/40428
> Reviewed-by: vpx_checkpatch status <vpx_checkpatch@broadcom.com>
> Reviewed-by: CCXSW <ccxswbuild@broadcom.com>
> Reviewed-by: Ray Jui <ray.jui@broadcom.com>
> Tested-by: vpx_autobuild status <vpx_autobuild@broadcom.com>
> Tested-by: vpx_smoketest status <vpx_smoketest@broadcom.com>
> Tested-by: CCXSW <ccxswbuild@broadcom.com>

All these non-person, probably internal Broadcom Tested-by and
Reviewed-by's should be removed too.

> Reviewed-by: Scott Branden <scott.branden@broadcom.com>
>

Rob

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Re: [PATCH 3/3] PCI/of fix of_dma_get_range; get PCI specific dma-ranges

[Oza Oza]

I will send v2 after removing GERRIT details from
commit message. My apologies for the noise.

Regards,
Oza

Re: [PATCH 3/3] PCI/of fix of_dma_get_range; get PCI specific dma-ranges

[Rob Herring]

On Tue, May 2, 2017 at 11:46 PM, Oza Pawandeep <oza.oza@broadcom.com> wrote:
> current device framework and of framework integration assumes
> dma-ranges in a way where memory-mapped devices define their
> dma-ranges. (child-bus-address, parent-bus-address, length).
>
> of_dma_configure is specifically written to take care of memory
> mapped devices. but no implementation exists for pci to take
> care of pcie based memory ranges.
>
> for e.g. iproc based SOCs and other SOCs(suc as rcar) have PCI
> world dma-ranges.
> dma-ranges = <0x43000000 0x00 0x00 0x00 0x00 0x80 0x00>;
>
> this patch fixes this patch fixes the bug in of_dma_get_range,
> which with as is, parses the PCI memory ranges and return wrong
> size as 0.
>
> in order to get largest possible dma_mask. this patch also
> retuns the largest possible size based on dma-ranges,
>
> for e.g.
> dma-ranges = <0x43000000 0x00 0x00 0x00 0x00 0x80 0x00>;
> we should get dev->coherent_dma_mask=0x7fffffffff.
>
> based on which iova allocation space will honour PCI host
> bridge limitations.
>
> Bug: SOC-5216
> Change-Id: I4c534bdd17e70c6b27327d39d1656e8ed0cf56d6
> Signed-off-by: Oza Pawandeep <oza.oza@broadcom.com>
> Reviewed-on: http://gerrit-ccxsw.broadcom.net/40762
> Reviewed-by: vpx_checkpatch status <vpx_checkpatch@broadcom.com>
> Reviewed-by: CCXSW <ccxswbuild@broadcom.com>
> Reviewed-by: Scott Branden <scott.branden@broadcom.com>
> Tested-by: vpx_autobuild status <vpx_autobuild@broadcom.com>
> Tested-by: vpx_smoketest status <vpx_smoketest@broadcom.com>
>
> diff --git a/drivers/of/address.c b/drivers/of/address.c
> index 02b2903..f7734fc 100644
> --- a/drivers/of/address.c
> +++ b/drivers/of/address.c
> @@ -6,6 +6,7 @@
>  #include <linux/ioport.h>
>  #include <linux/module.h>
>  #include <linux/of_address.h>
> +#include <linux/of_pci.h>
>  #include <linux/pci.h>
>  #include <linux/pci_regs.h>
>  #include <linux/sizes.h>
> @@ -830,6 +831,54 @@ int of_dma_get_range(struct device_node *np, u64 *dma_addr, u64 *paddr, u64 *siz
>         int ret = 0;
>         u64 dmaaddr;
>
> +#ifdef CONFIG_PCI
> +       struct resource_entry *window;
> +       LIST_HEAD(res);
> +
> +       if (!node)
> +               return -EINVAL;
> +
> +       if (of_bus_pci_match(np)) {

You are not following what I'm saying. Let me spell it out:

- Add a get_dma_ranges() function to of_bus struct. Or maybe should
cover ranges too (e.g. get_ranges). I'm not sure.
- Convert existing contents of this function to
of_bus_default_dma_get_ranges and add that to the default of_bus
struct.
- Make of_dma_get_range call of_bus_match() and then bus->get_dma_ranges.

Rob

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Re: [PATCH 1/3] of/pci/dma: fix DMA configuration for PCI masters

[Robin Murphy]

[apologies for the silence - I've been on holiday]

On 03/05/17 05:46, Oza Pawandeep wrote:
> current device framework and of framework integration assumes
> dma-ranges in a way where memory-mapped devices define their
> dma-ranges. (child-bus-address, parent-bus-address, length).

Well, yes, that is simply the definition of dma-ranges, and remains true
regardless of the particular format of either bus address.

> of_dma_configure is specifically written to take care of memory
> mapped devices. but no implementation exists for pci to take
> care of pcie based memory ranges.

That still doesn't make sense. To repeat myself again, PCI devices *ARE*
memory-mapped devices. Yes, there do exist some platforms where I/O
space is not treated as MMIO, but config space and memory space are very
much memory-mapped however you look at them, and in the context of DMA,
only memory space is relevant anyway.

What *is* true about the current code is that of_dma_get_range() expects
to be passed an OF node representing the device itself, and doesn't work
properly when passed the node of the device's parent bus directly, which
happens to be what pci_dma_configure() currently does. That's the only
reason why it doesn't work for (single-entry) host controller dma-ranges
today. This does not mean it's a PCI problem, it is simply the case that
pci_dma_configure() is the only caller currently hitting it. Other
discoverable, DMA-capable buses like fsl-mc are still going to face the
exact same problem with or without this patch.

> for e.g. iproc based SOCs and other SOCs(suc as rcar) have PCI
> world dma-ranges.
> dma-ranges = <0x43000000 0x00 0x00 0x00 0x00 0x80 0x00>;
> 
> this patch serves following:
> 
> 1) exposes interface to the pci host driver for their
> inbound memory ranges
> 
> 2) provide an interface to callers such as of_dma_get_ranges.
> so then the returned size get best possible (largest) dma_mask.
> because PCI RC drivers do not call APIs such as
> dma_set_coherent_mask() and hence rather it shows its addressing
> capabilities based on dma-ranges.
> for e.g.
> dma-ranges = <0x43000000 0x00 0x00 0x00 0x00 0x80 0x00>;
> we should get dev->coherent_dma_mask=0x7fffffffff.
> 
> 3) this patch handles multiple inbound windows and dma-ranges.
> it is left to the caller, how it wants to use them.
> the new function returns the resources in a standard and unform way
> 
> 4) this way the callers of for e.g. of_dma_get_ranges
> does not need to change.
> 
> 5) leaves scope of adding PCI flag handling for inbound memory
> by the new function.

Which flags would ever actually matter? DMA windows aren't going to be
to config or I/O space, so the memory type can be assumed, and the
32/64-bit distinction is irrelevant as it's not a relocatable BAR;
DMA-able system memory isn't going to be read-sensitive, so the
prefetchable flag shouldn't matter; and not being a BAR none of the
others would be relevant either.

> 
> Bug: SOC-5216
> Change-Id: Ie045386df91e1e0587846bb147ae40d96f6d7d2e
> Signed-off-by: Oza Pawandeep <oza.oza@broadcom.com>
> Reviewed-on: http://gerrit-ccxsw.broadcom.net/40428
> Reviewed-by: vpx_checkpatch status <vpx_checkpatch@broadcom.com>
> Reviewed-by: CCXSW <ccxswbuild@broadcom.com>
> Reviewed-by: Ray Jui <ray.jui@broadcom.com>
> Tested-by: vpx_autobuild status <vpx_autobuild@broadcom.com>
> Tested-by: vpx_smoketest status <vpx_smoketest@broadcom.com>
> Tested-by: CCXSW <ccxswbuild@broadcom.com>
> Reviewed-by: Scott Branden <scott.branden@broadcom.com>
> 
> diff --git a/drivers/of/of_pci.c b/drivers/of/of_pci.c
> index 0ee42c3..ed6e69a 100644
> --- a/drivers/of/of_pci.c
> +++ b/drivers/of/of_pci.c
> @@ -283,6 +283,83 @@ int of_pci_get_host_bridge_resources(struct device_node *dev,
>  	return err;
>  }
>  EXPORT_SYMBOL_GPL(of_pci_get_host_bridge_resources);
> +
> +/**
> + * of_pci_get_dma_ranges - Parse PCI host bridge inbound resources from DT
> + * @np: device node of the host bridge having the dma-ranges property
> + * @resources: list where the range of resources will be added after DT parsing
> + *
> + * It is the caller's job to free the @resources list.
> + *
> + * This function will parse the "dma-ranges" property of a
> + * PCI host bridge device node and setup the resource mapping based
> + * on its content.
> + *
> + * It returns zero if the range parsing has been successful or a standard error
> + * value if it failed.
> + */
> +
> +int of_pci_get_dma_ranges(struct device_node *np, struct list_head *resources)
> +{
> +	struct device_node *node = of_node_get(np);
> +	int rlen;
> +	int ret = 0;
> +	const int na = 3, ns = 2;
> +	struct resource *res;
> +	struct of_pci_range_parser parser;
> +	struct of_pci_range range;
> +
> +	if (!node)
> +		return -EINVAL;
> +
> +	parser.node = node;
> +	parser.pna = of_n_addr_cells(node);
> +	parser.np = parser.pna + na + ns;
> +
> +	parser.range = of_get_property(node, "dma-ranges", &rlen);
> +
> +	if (!parser.range) {
> +		pr_debug("pcie device has no dma-ranges defined for node(%s)\n",
> +			  np->full_name);
> +		ret = -EINVAL;
> +		goto out;
> +	}
> +
> +	parser.end = parser.range + rlen / sizeof(__be32);
> +
> +	for_each_of_pci_range(&parser, &range) {

This is plain wrong - of_pci_range_parser_one() will translate upwards
through parent "ranges" properties, which is completely backwards for
DMA addresses.

Robin.

> +		/*
> +		 * If we failed translation or got a zero-sized region
> +		 * then skip this range
> +		 */
> +		if (range.cpu_addr == OF_BAD_ADDR || range.size == 0)
> +			continue;
> +
> +		res = kzalloc(sizeof(struct resource), GFP_KERNEL);
> +		if (!res) {
> +			ret = -ENOMEM;
> +			goto parse_failed;
> +		}
> +
> +		ret = of_pci_range_to_resource(&range, np, res);
> +		if (ret) {
> +			kfree(res);
> +			continue;
> +		}
> +
> +		pci_add_resource_offset(resources, res,
> +					res->start - range.pci_addr);
> +	}
> +
> +	return ret;
> +
> +parse_failed:
> +	pci_free_resource_list(resources);
> +out:
> +	of_node_put(node);
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(of_pci_get_dma_ranges);
>  #endif /* CONFIG_OF_ADDRESS */
>  
>  #ifdef CONFIG_PCI_MSI
> diff --git a/include/linux/of_pci.h b/include/linux/of_pci.h
> index 0e0974e..617b90d 100644
> --- a/include/linux/of_pci.h
> +++ b/include/linux/of_pci.h
> @@ -76,6 +76,7 @@ static inline void of_pci_check_probe_only(void) { }
>  int of_pci_get_host_bridge_resources(struct device_node *dev,
>  			unsigned char busno, unsigned char bus_max,
>  			struct list_head *resources, resource_size_t *io_base);
> +int of_pci_get_dma_ranges(struct device_node *np, struct list_head *resources);
>  #else
>  static inline int of_pci_get_host_bridge_resources(struct device_node *dev,
>  			unsigned char busno, unsigned char bus_max,
> @@ -83,6 +84,12 @@ static inline int of_pci_get_host_bridge_resources(struct device_node *dev,
>  {
>  	return -EINVAL;
>  }
> +
> +static inline int of_pci_get_dma_ranges(struct device_node *np,
> +					struct list_head *resources)
> +{
> +	return -EINVAL;
> +}
>  #endif
>  
>  #if defined(CONFIG_OF) && defined(CONFIG_PCI_MSI)
> 

Re: [PATCH 1/3] of/pci/dma: fix DMA configuration for PCI masters

[Robin Murphy]

On 04/05/17 19:41, Oza Oza wrote:
[...]
>>> 5) leaves scope of adding PCI flag handling for inbound memory
>>> by the new function.
>>
>> Which flags would ever actually matter? DMA windows aren't going to be
>> to config or I/O space, so the memory type can be assumed, and the
>> 32/64-bit distinction is irrelevant as it's not a relocatable BAR;
>> DMA-able system memory isn't going to be read-sensitive, so the
>> prefetchable flag shouldn't matter; and not being a BAR none of the
>> others would be relevant either.
>>
> 
> Thanks Robin; for your reply and attention:
> 
> agree with you, at present it would not matter,
> but it does not mean that we do not scope it to make it matter in future.
> 
> now where it could matter:
> there is Relaxed Ordering for inbound memory for PCI.
> According to standard, Relaxed Ordering (RO) bit can be set only for
> Memory requests and completions (if present in the original request).
> Also, according to transaction ordering rules, I/O and configuration
> requests can still be re-ordered ahead of each other.
> and we would like to make use of it.
> for e.g. lets say we mark memory as Relaxed Ordered with flag.
> the special about this memory is incoming PCI transactions can be
> reordered and rest memory has to be strongly ordered.

Please look at "PCI Bus Binding to: IEEE Std 1275-1994 Standard for Boot
(Initialization Configuration) Firmware" (as referenced in DTSpec) and
explain how PCIe Relaxed Order has anything to do with the DT binding.

> how it our SOC would make use of this is out of scope for the
> discussion at this point of time, but I am just bringing in the
> idea/point how flags could be useful
> for inbound memory, since we would not like throw-away flags completely.

The premise for implementing a PCI-specific parser is that you claim we
need to do something with the phys.hi cell of a DT PCI address, rather
than just taking the numerical part out of the phys.mid and phys.lo
cells. Please make that argument in reference to the flags which that
upper cell actually encodes, not unrelated things.

[...]
>>> +int of_pci_get_dma_ranges(struct device_node *np, struct list_head *resources)
>>> +{
>>> +     struct device_node *node = of_node_get(np);
>>> +     int rlen;
>>> +     int ret = 0;
>>> +     const int na = 3, ns = 2;
>>> +     struct resource *res;
>>> +     struct of_pci_range_parser parser;
>>> +     struct of_pci_range range;
>>> +
>>> +     if (!node)
>>> +             return -EINVAL;
>>> +
>>> +     parser.node = node;
>>> +     parser.pna = of_n_addr_cells(node);
>>> +     parser.np = parser.pna + na + ns;
>>> +
>>> +     parser.range = of_get_property(node, "dma-ranges", &rlen);
>>> +
>>> +     if (!parser.range) {
>>> +             pr_debug("pcie device has no dma-ranges defined for node(%s)\n",
>>> +                       np->full_name);
>>> +             ret = -EINVAL;
>>> +             goto out;
>>> +     }
>>> +
>>> +     parser.end = parser.range + rlen / sizeof(__be32);
>>> +
>>> +     for_each_of_pci_range(&parser, &range) {
>>
>> This is plain wrong - of_pci_range_parser_one() will translate upwards
>> through parent "ranges" properties, which is completely backwards for
>> DMA addresses.
>>
>> Robin.
>>
> 
> No it does not, this patch is thoroughly tested on our SOC and it works.
> of_pci_range_parser_one does not translate upwards through parent. it
> just sticks to given PCI parser.

Frankly, I'm losing patience with this attitude. Please look at the code
you call:

#define for_each_of_pci_range(parser, range) \
	for (; of_pci_range_parser_one(parser, range);)


struct of_pci_range *of_pci_range_parser_one(struct of_pci_range_parser
*parser,
						struct of_pci_range *range)
{
	const int na = 3, ns = 2;

	if (!range)
		return NULL;

	if (!parser->range || parser->range + parser->np > parser->end)
		return NULL;

	range->pci_space = parser->range[0];
	range->flags = of_bus_pci_get_flags(parser->range);
	range->pci_addr = of_read_number(parser->range + 1, ns);
	range->cpu_addr = of_translate_address(parser->node,
				parser->range + na);
...


u64 of_translate_address(struct device_node *dev, const __be32 *in_addr)
{
	return __of_translate_address(dev, in_addr, "ranges");
}


I don't doubt that you still manage to get the right result on *your*
SoC, because you probably have neither further "ranges" nor "dma-ranges"
translations above your host controller node anyway. That does not
change the fact that the proposed code is still obviously wrong for more
complex DT topologies that do.

We're doing upstream work in core code here: I don't particularly care
about making your SoC work; I don't really care about making Juno work
properly either; what I do care about is that code to parse dma-ranges
actually parses dma-ranges *correctly* for all possible valid uses of
dma-ranges, which means fixing the existing bugs and not introducing
more. The principal side-effect of that is that *all* systems with valid
DTs will then work correctly.

Robin.

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Re: [PATCH 2/3] iommu/pci: reserve iova for PCI masters

[Robin Murphy]

On 03/05/17 05:46, Oza Pawandeep wrote:
> this patch reserves the iova for PCI masters.
> ARM64 based SOCs may have scattered memory banks.
> such as iproc based SOC has
> 
> <0x00000000 0x80000000 0x0 0x80000000>, /* 2G @ 2G */
> <0x00000008 0x80000000 0x3 0x80000000>, /* 14G @ 34G */
> <0x00000090 0x00000000 0x4 0x00000000>, /* 16G @ 576G */
> <0x000000a0 0x00000000 0x4 0x00000000>; /* 16G @ 640G */
> 
> but incoming PCI transcation addressing capability is limited
> by host bridge, for example if max incoming window capability
> is 512 GB, then 0x00000090 and 0x000000a0 will fall beyond it.
> 
> to address this problem, iommu has to avoid allocating iovas which
> are reserved. which inturn does not allocate iova if it falls into hole.

I don't necessarily disagree with doing this, as we could do with facing
up to the issue of discontiguous DMA ranges in particular (I too have a
platform with this problem), but I'm still not overly keen on pulling DT
specifics into this layer. More than that, though, if we are going to do
it, then we should do it for all devices with a restrictive
"dma-ranges", not just PCI ones.

> Bug: SOC-5216
> Change-Id: Icbfc99a045d730be143fef427098c937b9d46353
> Signed-off-by: Oza Pawandeep <oza.oza@broadcom.com>
> Reviewed-on: http://gerrit-ccxsw.broadcom.net/40760
> Reviewed-by: vpx_checkpatch status <vpx_checkpatch@broadcom.com>
> Reviewed-by: CCXSW <ccxswbuild@broadcom.com>
> Tested-by: vpx_autobuild status <vpx_autobuild@broadcom.com>
> Tested-by: vpx_smoketest status <vpx_smoketest@broadcom.com>
> Tested-by: CCXSW <ccxswbuild@broadcom.com>
> Reviewed-by: Scott Branden <scott.branden@broadcom.com>
> 
> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
> index 48d36ce..08764b0 100644
> --- a/drivers/iommu/dma-iommu.c
> +++ b/drivers/iommu/dma-iommu.c
> @@ -27,6 +27,7 @@
>  #include <linux/iova.h>
>  #include <linux/irq.h>
>  #include <linux/mm.h>
> +#include <linux/of_pci.h>
>  #include <linux/pci.h>
>  #include <linux/scatterlist.h>
>  #include <linux/vmalloc.h>
> @@ -171,8 +172,12 @@ static void iova_reserve_pci_windows(struct pci_dev *dev,
>  		struct iova_domain *iovad)
>  {
>  	struct pci_host_bridge *bridge = pci_find_host_bridge(dev->bus);
> +	struct device_node *np = bridge->dev.parent->of_node;
>  	struct resource_entry *window;
>  	unsigned long lo, hi;
> +	int ret;
> +	dma_addr_t tmp_dma_addr = 0, dma_addr;
> +	LIST_HEAD(res);
>  
>  	resource_list_for_each_entry(window, &bridge->windows) {
>  		if (resource_type(window->res) != IORESOURCE_MEM &&
> @@ -183,6 +188,36 @@ static void iova_reserve_pci_windows(struct pci_dev *dev,
>  		hi = iova_pfn(iovad, window->res->end - window->offset);
>  		reserve_iova(iovad, lo, hi);
>  	}
> +
> +	/* PCI inbound memory reservation. */
> +	ret = of_pci_get_dma_ranges(np, &res);
> +	if (!ret) {
> +		resource_list_for_each_entry(window, &res) {
> +			struct resource *res_dma = window->res;
> +
> +			dma_addr = res_dma->start - window->offset;
> +			if (tmp_dma_addr > dma_addr) {
> +				pr_warn("PCI: failed to reserve iovas; ranges should be sorted\n");

I don't see anything in the DT spec about the entries having to be
sorted, and it's not exactly impossible to sort a list if you need it so
(and if I'm being really pedantic, one could still trigger this with a
list that *is* sorted, only by different criteria).

Robin.

> +				return;
> +			}
> +			if (tmp_dma_addr != dma_addr) {
> +				lo = iova_pfn(iovad, tmp_dma_addr);
> +				hi = iova_pfn(iovad, dma_addr - 1);
> +				reserve_iova(iovad, lo, hi);
> +			}
> +			tmp_dma_addr = window->res->end - window->offset;
> +		}
> +		/*
> +		 * the last dma-range should honour based on the
> +		 * 32/64-bit dma addresses.
> +		 */
> +		if (tmp_dma_addr < DMA_BIT_MASK(sizeof(dma_addr_t) * 8)) {
> +			lo = iova_pfn(iovad, tmp_dma_addr);
> +			hi = iova_pfn(iovad,
> +				      DMA_BIT_MASK(sizeof(dma_addr_t) * 8) - 1);
> +			reserve_iova(iovad, lo, hi);
> +		}
> +	}
>  }
>  
>  /**
> 

Re: [PATCH 2/3] iommu/pci: reserve iova for PCI masters

[Robin Murphy]

On 04/05/17 19:52, Oza Oza wrote:
> On Thu, May 4, 2017 at 11:50 PM, Robin Murphy <robin.murphy@arm.com> wrote:
>> On 03/05/17 05:46, Oza Pawandeep wrote:
>>> this patch reserves the iova for PCI masters.
>>> ARM64 based SOCs may have scattered memory banks.
>>> such as iproc based SOC has
>>>
>>> <0x00000000 0x80000000 0x0 0x80000000>, /* 2G @ 2G */
>>> <0x00000008 0x80000000 0x3 0x80000000>, /* 14G @ 34G */
>>> <0x00000090 0x00000000 0x4 0x00000000>, /* 16G @ 576G */
>>> <0x000000a0 0x00000000 0x4 0x00000000>; /* 16G @ 640G */
>>>
>>> but incoming PCI transcation addressing capability is limited
>>> by host bridge, for example if max incoming window capability
>>> is 512 GB, then 0x00000090 and 0x000000a0 will fall beyond it.
>>>
>>> to address this problem, iommu has to avoid allocating iovas which
>>> are reserved. which inturn does not allocate iova if it falls into hole.
>>
>> I don't necessarily disagree with doing this, as we could do with facing
>> up to the issue of discontiguous DMA ranges in particular (I too have a
>> platform with this problem), but I'm still not overly keen on pulling DT
>> specifics into this layer. More than that, though, if we are going to do
>> it, then we should do it for all devices with a restrictive
>> "dma-ranges", not just PCI ones.
>>
> 
> How do you propose to do it ?
> 
> my thinking is this:
> iova_reserve_pci_windows is written specific for PCI, and I am adding there.
> 
> ideally
> struct pci_host_bridge should have new member:
> 
> struct list_head inbound_windows; /* resource_entry */
> 
> but somehow this resource have to be filled much before
> iommu_dma_init_domain happens.
> and use brdge resource directly in iova_reserve_pci_windows as it is
> already doing it for outbound memory.
> 
> this will detach the DT specifics from dma-immu layer.
> let me know how this sounds.

Please check the state of the code currently queued in Joerg's tree and
in linux-next - iommu_dma_get_resv_regions() has room for
device-agnostic stuff before the if (!dev_is_pci(dev)) check.

Furthermore, with the probe-deferral changes we end up with a common
dma_configure() routine to abstract the firmware-specifics of
of_dma_configure() vs. acpi_dma_configure(), so it would make sense to
give drivers etc. a similar interface for interrogating ranges. i.e.
some common function that abstracts the difference between parsing DT
dma-ranges vs. the ACPI _DMA object, either with a list-based get/put
model or perhaps an iterator with a user-provided callback (so users
could process in-place or create their own list as necessary). Unless of
course we go all the way to making the ranges an inherent part of the
device layer like some MIPS platforms currently do.

Robin.

>>> Bug: SOC-5216
>>> Change-Id: Icbfc99a045d730be143fef427098c937b9d46353
>>> Signed-off-by: Oza Pawandeep <oza.oza@broadcom.com>
>>> Reviewed-on: http://gerrit-ccxsw.broadcom.net/40760
>>> Reviewed-by: vpx_checkpatch status <vpx_checkpatch@broadcom.com>
>>> Reviewed-by: CCXSW <ccxswbuild@broadcom.com>
>>> Tested-by: vpx_autobuild status <vpx_autobuild@broadcom.com>
>>> Tested-by: vpx_smoketest status <vpx_smoketest@broadcom.com>
>>> Tested-by: CCXSW <ccxswbuild@broadcom.com>
>>> Reviewed-by: Scott Branden <scott.branden@broadcom.com>
>>>
>>> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
>>> index 48d36ce..08764b0 100644
>>> --- a/drivers/iommu/dma-iommu.c
>>> +++ b/drivers/iommu/dma-iommu.c
>>> @@ -27,6 +27,7 @@
>>>  #include <linux/iova.h>
>>>  #include <linux/irq.h>
>>>  #include <linux/mm.h>
>>> +#include <linux/of_pci.h>
>>>  #include <linux/pci.h>
>>>  #include <linux/scatterlist.h>
>>>  #include <linux/vmalloc.h>
>>> @@ -171,8 +172,12 @@ static void iova_reserve_pci_windows(struct pci_dev *dev,
>>>               struct iova_domain *iovad)
>>>  {
>>>       struct pci_host_bridge *bridge = pci_find_host_bridge(dev->bus);
>>> +     struct device_node *np = bridge->dev.parent->of_node;
>>>       struct resource_entry *window;
>>>       unsigned long lo, hi;
>>> +     int ret;
>>> +     dma_addr_t tmp_dma_addr = 0, dma_addr;
>>> +     LIST_HEAD(res);
>>>
>>>       resource_list_for_each_entry(window, &bridge->windows) {
>>>               if (resource_type(window->res) != IORESOURCE_MEM &&
>>> @@ -183,6 +188,36 @@ static void iova_reserve_pci_windows(struct pci_dev *dev,
>>>               hi = iova_pfn(iovad, window->res->end - window->offset);
>>>               reserve_iova(iovad, lo, hi);
>>>       }
>>> +
>>> +     /* PCI inbound memory reservation. */
>>> +     ret = of_pci_get_dma_ranges(np, &res);
>>> +     if (!ret) {
>>> +             resource_list_for_each_entry(window, &res) {
>>> +                     struct resource *res_dma = window->res;
>>> +
>>> +                     dma_addr = res_dma->start - window->offset;
>>> +                     if (tmp_dma_addr > dma_addr) {
>>> +                             pr_warn("PCI: failed to reserve iovas; ranges should be sorted\n");
>>
>> I don't see anything in the DT spec about the entries having to be
>> sorted, and it's not exactly impossible to sort a list if you need it so
>> (and if I'm being really pedantic, one could still trigger this with a
>> list that *is* sorted, only by different criteria).
>>
> 
> we have to sort it the way we want then. I can make it sort then.
> thanks for the suggestion.
> 
>> Robin.
>>
>>> +                             return;
>>> +                     }
>>> +                     if (tmp_dma_addr != dma_addr) {
>>> +                             lo = iova_pfn(iovad, tmp_dma_addr);
>>> +                             hi = iova_pfn(iovad, dma_addr - 1);
>>> +                             reserve_iova(iovad, lo, hi);
>>> +                     }
>>> +                     tmp_dma_addr = window->res->end - window->offset;
>>> +             }
>>> +             /*
>>> +              * the last dma-range should honour based on the
>>> +              * 32/64-bit dma addresses.
>>> +              */
>>> +             if (tmp_dma_addr < DMA_BIT_MASK(sizeof(dma_addr_t) * 8)) {
>>> +                     lo = iova_pfn(iovad, tmp_dma_addr);
>>> +                     hi = iova_pfn(iovad,
>>> +                                   DMA_BIT_MASK(sizeof(dma_addr_t) * 8) - 1);
>>> +                     reserve_iova(iovad, lo, hi);
>>> +             }
>>> +     }
>>>  }
>>>
>>>  /**
>>>
>>


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