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Subject: Re: [PATCH V4 1/2] ACPI / scan: Support multiple dma windows with
 different offsets
To:     Robin Murphy <robin.murphy@arm.com>,
        Lorenzo Pieralisi <lpieralisi@kernel.org>
Cc:     chenhuacai@loongson.cn, guohanjun@huawei.com, sudeep.holla@arm.com,
        rafael@kernel.org, lenb@kernel.org, robert.moore@intel.com,
        linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org,
        loongarch@lists.linux.dev
References: <20220909092811.22627-1-lvjianmin@loongson.cn>
 <20220909092811.22627-2-lvjianmin@loongson.cn> <YxshQ7IR1vtnimbh@lpieralisi>
 <934e3fb9-4fb6-cc97-4cc5-7d85591ae939@arm.com>
From:   Jianmin Lv <lvjianmin@loongson.cn>
Message-ID: <3f154364-ad7b-e98b-7580-e71d90de49d3@loongson.cn>
Date:   Fri, 9 Sep 2022 21:08:04 +0800
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On 2022/9/9 下午7:48, Robin Murphy wrote:
> On 2022-09-09 12:19, Lorenzo Pieralisi wrote:
>> On Fri, Sep 09, 2022 at 05:28:10PM +0800, Jianmin Lv wrote:
>>> For DT, of_dma_get_range returns bus_dma_region typed dma regions,
>>> which makes multiple dma windows with different offset available
>>> for translation between dma address and cpu address.
>>>
>>> But for ACPI, acpi_dma_get_range doesn't return similar dma regions,
>>> causing no path for setting dev->dma_range_map conveniently. So the
>>> patch changes acpi_dma_get_range and returns bus_dma_region typed
>>> dma regions according to of_dma_get_range.
>>>
>>> After changing acpi_dma_get_range, acpi_arch_dma_setup is changed for
>>> ARM64, where original dma_addr and size are removed as these
>>> arguments are now redundant, and pass 0 and U64_MAX for dma_base
>>> and size of arch_setup_dma_ops, so this is a simplification consistent
>>> with what other ACPI architectures also pass to iommu_setup_dma_ops().
>>
>> How about this commit log:
>>
>> "In DT systems configurations, of_dma_get_range() returns struct
>> bus_dma_region DMA regions; they are used to set-up devices
>> DMA windows with different offset available for translation between DMA
>> address and CPU address.
>>
>> In ACPI systems configuration, acpi_dma_get_range() does not return
>> DMA regions yet and that precludes setting up the dev->dma_range_map
>> pointer and therefore DMA regions with multiple offsets.
>>
>> Update acpi_dma_get_range() to return struct bus_dma_region
>> DMA regions like of_dma_get_range() does.
>>
>> After updating acpi_dma_get_range(), acpi_arch_dma_setup() is changed for
>> ARM64, where the original dma_addr and size are removed as these
>> arguments are now redundant, and pass 0 and U64_MAX for dma_base
>> and size of arch_setup_dma_ops; this is a simplification consistent
>> with what other ACPI architectures also pass to iommu_setup_dma_ops()."
>>

Sure, it seem that the log is more better than before, thanks very much！

Jianmin

>>>
>>> Reviewed-by: Robin Murphy <robin.murphy@arm.com>
>>> Signed-off-by: Jianmin Lv <lvjianmin@loongson.cn>
>>> ---
>>>   drivers/acpi/arm64/dma.c | 29 +++++++++++++---------
>>>   drivers/acpi/scan.c      | 53 +++++++++++++++++-----------------------
>>>   include/acpi/acpi_bus.h  |  3 +--
>>>   include/linux/acpi.h     |  7 +++---
>>>   4 files changed, 45 insertions(+), 47 deletions(-)
>>>
>>> diff --git a/drivers/acpi/arm64/dma.c b/drivers/acpi/arm64/dma.c
>>> index f16739ad3cc0..1ef8e7ded4cd 100644
>>> --- a/drivers/acpi/arm64/dma.c
>>> +++ b/drivers/acpi/arm64/dma.c
>>> @@ -4,11 +4,12 @@
>>>   #include <linux/device.h>
>>>   #include <linux/dma-direct.h>
>>> -void acpi_arch_dma_setup(struct device *dev, u64 *dma_addr, u64 
>>> *dma_size)
>>> +void acpi_arch_dma_setup(struct device *dev)
>>>   {
>>>       int ret;
>>>       u64 end, mask;
>>> -    u64 dmaaddr = 0, size = 0, offset = 0;
>>> +    u64 size = 0;
>>> +    const struct bus_dma_region *map = NULL;
>>>       /*
>>>        * If @dev is expected to be DMA-capable then the bus code that 
>>> created
>>> @@ -26,25 +27,31 @@ void acpi_arch_dma_setup(struct device *dev, u64 
>>> *dma_addr, u64 *dma_size)
>>>       else
>>>           size = 1ULL << 32;
>>> -    ret = acpi_dma_get_range(dev, &dmaaddr, &offset, &size);
>>> +    ret = acpi_dma_get_range(dev, &map);
>>> +    if (!ret && map) {
>>> +        const struct bus_dma_region *r = map;
>>> +
>>> +        for (end = 0; r->size; r++) {
>>> +            if (r->dma_start + r->size - 1 > end)
>>> +                end = r->dma_start + r->size - 1;
>>> +        }
>>> +
>>> +        size = end + 1;
>>> +        dev->dma_range_map = map;
>>> +    }
>>> +
>>>       if (ret == -ENODEV)
>>>           ret = iort_dma_get_ranges(dev, &size);
>>> +
>>
>> Nit: this is a spurious line change.
>>

Ok, I'll remove it.


>>>       if (!ret) {
>>>           /*
>>>            * Limit coherent and dma mask based on size retrieved from
>>>            * firmware.
>>>            */
>>> -        end = dmaaddr + size - 1;
>>> +        end = size - 1;
>>>           mask = DMA_BIT_MASK(ilog2(end) + 1);
>>>           dev->bus_dma_limit = end;
>>>           dev->coherent_dma_mask = min(dev->coherent_dma_mask, mask);
>>>           *dev->dma_mask = min(*dev->dma_mask, mask);
>>>       }
>>> -
>>> -    *dma_addr = dmaaddr;
>>> -    *dma_size = size;
>>> -
>>> -    ret = dma_direct_set_offset(dev, dmaaddr + offset, dmaaddr, size);
>>> -
>>> -    dev_dbg(dev, "dma_offset(%#08llx)%s\n", offset, ret ? " failed!" 
>>> : "");
>>>   }
>>> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
>>> index 42cec8120f18..b4505ec467fe 100644
>>> --- a/drivers/acpi/scan.c
>>> +++ b/drivers/acpi/scan.c
>>> @@ -20,6 +20,7 @@
>>>   #include <linux/platform_data/x86/apple.h>
>>>   #include <linux/pgtable.h>
>>>   #include <linux/crc32.h>
>>> +#include <linux/dma-direct.h>
>>>   #include "internal.h"
>>> @@ -1467,25 +1468,21 @@ enum dev_dma_attr acpi_get_dma_attr(struct 
>>> acpi_device *adev)
>>>    * acpi_dma_get_range() - Get device DMA parameters.
>>>    *
>>>    * @dev: device to configure
>>> - * @dma_addr: pointer device DMA address result
>>> - * @offset: pointer to the DMA offset result
>>> - * @size: pointer to DMA range size result
>>> + * @map: pointer to DMA ranges result
>>>    *
>>> - * Evaluate DMA regions and return respectively DMA region start, 
>>> offset
>>> - * and size in dma_addr, offset and size on parsing success; it does 
>>> not
>>> - * update the passed in values on failure.
>>> + * Evaluate DMA regions and return pointer to DMA regions on
>>> + * parsing success; it does not update the passed in values on failure.
>>>    *
>>>    * Return 0 on success, < 0 on failure.
>>>    */
>>> -int acpi_dma_get_range(struct device *dev, u64 *dma_addr, u64 *offset,
>>> -               u64 *size)
>>> +int acpi_dma_get_range(struct device *dev, const struct 
>>> bus_dma_region **map)
>>>   {
>>>       struct acpi_device *adev;
>>>       LIST_HEAD(list);
>>>       struct resource_entry *rentry;
>>>       int ret;
>>>       struct device *dma_dev = dev;
>>> -    u64 len, dma_start = U64_MAX, dma_end = 0, dma_offset = 0;
>>> +    struct bus_dma_region *r;
>>>       /*
>>>        * Walk the device tree chasing an ACPI companion with a _DMA
>>> @@ -1510,31 +1507,28 @@ int acpi_dma_get_range(struct device *dev, 
>>> u64 *dma_addr, u64 *offset,
>>>       ret = acpi_dev_get_dma_resources(adev, &list);
>>>       if (ret > 0) {
>>> +        r = kcalloc(ret + 1, sizeof(*r), GFP_KERNEL);
>>
>> Why (ret + 1) ?
> 
> The range map is terminated by an entry with size == 0, although the 
> equivalent allocations in of_dma_get_range() and dma_direct_set_offset() 
> are similarly uncommented.
> 

Yes, really.

>>> +        if (!r) {
>>> +            ret = -ENOMEM;
>>> +            goto out;
>>> +        }
>>> +
>>> +        *map = r;
>>
>> I don't think that's right. This function can still fail at this stage,
>> we should not update the *map value yet.
> 
> The caller does at least correctly ignore the map if we return failure, 
> but I guess it is still at odds with the kerneldoc saying "it does not 
> update the passed in values on failure", and presumably the allocation 
> also ends up being leaked in that case. Dang, sorry I missed this in my 
> last review...

Sorry, it's really a bug code here, I'll change it as following:

                r = kcalloc(ret + 1, sizeof(*r), GFP_KERNEL);
                 if (!r) {
                         ret = -ENOMEM;
                         goto out;
                 }

                 list_for_each_entry(rentry, &list, node) {
                         if (rentry->res->start >= rentry->res->end) {
                                 kfree(r);
                                 ret = -EINVAL;
                                 dev_dbg(dma_dev, "Invalid DMA regions 
configuration\n");
                                 goto out;
                         }

                         r->cpu_start = rentry->res->start;
                         r->dma_start = rentry->res->start - rentry->offset;
                         r->size = resource_size(rentry->res);
                         r->offset = rentry->offset;
                         r++;
                 }

                 *map = r;

Thanks,
Jianmin


> 
> Cheers,
> Robin.
> 
>>
>> Lorenzo
>>
>>> +
>>>           list_for_each_entry(rentry, &list, node) {
>>> -            if (dma_offset && rentry->offset != dma_offset) {
>>> +            if (rentry->res->start >= rentry->res->end) {
>>>                   ret = -EINVAL;
>>> -                dev_warn(dma_dev, "Can't handle multiple windows 
>>> with different offsets\n");
>>> +                dev_dbg(dma_dev, "Invalid DMA regions 
>>> configuration\n");
>>>                   goto out;
>>>               }
>>> -            dma_offset = rentry->offset;
>>> -            /* Take lower and upper limits */
>>> -            if (rentry->res->start < dma_start)
>>> -                dma_start = rentry->res->start;
>>> -            if (rentry->res->end > dma_end)
>>> -                dma_end = rentry->res->end;
>>> -        }
>>> -
>>> -        if (dma_start >= dma_end) {
>>> -            ret = -EINVAL;
>>> -            dev_dbg(dma_dev, "Invalid DMA regions configuration\n");
>>> -            goto out;
>>> +            r->cpu_start = rentry->res->start;
>>> +            r->dma_start = rentry->res->start - rentry->offset;
>>> +            r->size = resource_size(rentry->res);
>>> +            r->offset = rentry->offset;
>>> +            r++;
>>>           }
>>> -        *dma_addr = dma_start - dma_offset;
>>> -        len = dma_end - dma_start;
>>> -        *size = max(len, len + 1);
>>> -        *offset = dma_offset;
>>>       }
>>>    out:
>>>       acpi_dev_free_resource_list(&list);
>>> @@ -1624,20 +1618,19 @@ int acpi_dma_configure_id(struct device *dev, 
>>> enum dev_dma_attr attr,
>>>                 const u32 *input_id)
>>>   {
>>>       const struct iommu_ops *iommu;
>>> -    u64 dma_addr = 0, size = 0;
>>>       if (attr == DEV_DMA_NOT_SUPPORTED) {
>>>           set_dma_ops(dev, &dma_dummy_ops);
>>>           return 0;
>>>       }
>>> -    acpi_arch_dma_setup(dev, &dma_addr, &size);
>>> +    acpi_arch_dma_setup(dev);
>>>       iommu = acpi_iommu_configure_id(dev, input_id);
>>>       if (PTR_ERR(iommu) == -EPROBE_DEFER)
>>>           return -EPROBE_DEFER;
>>> -    arch_setup_dma_ops(dev, dma_addr, size,
>>> +    arch_setup_dma_ops(dev, 0, U64_MAX,
>>>                   iommu, attr == DEV_DMA_COHERENT);
>>>       return 0;
>>> diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
>>> index e7d27373ff71..73ac4a1d6947 100644
>>> --- a/include/acpi/acpi_bus.h
>>> +++ b/include/acpi/acpi_bus.h
>>> @@ -613,8 +613,7 @@ enum dev_dma_attr acpi_get_dma_attr(struct 
>>> acpi_device *adev);
>>>   int acpi_iommu_fwspec_init(struct device *dev, u32 id,
>>>                  struct fwnode_handle *fwnode,
>>>                  const struct iommu_ops *ops);
>>> -int acpi_dma_get_range(struct device *dev, u64 *dma_addr, u64 *offset,
>>> -               u64 *size);
>>> +int acpi_dma_get_range(struct device *dev, const struct 
>>> bus_dma_region **map);
>>>   int acpi_dma_configure_id(struct device *dev, enum dev_dma_attr attr,
>>>                  const u32 *input_id);
>>>   static inline int acpi_dma_configure(struct device *dev,
>>> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
>>> index 6f64b2f3dc54..bb41623dab77 100644
>>> --- a/include/linux/acpi.h
>>> +++ b/include/linux/acpi.h
>>> @@ -281,12 +281,12 @@ void acpi_numa_x2apic_affinity_init(struct 
>>> acpi_srat_x2apic_cpu_affinity *pa);
>>>   #ifdef CONFIG_ARM64
>>>   void acpi_numa_gicc_affinity_init(struct acpi_srat_gicc_affinity *pa);
>>> -void acpi_arch_dma_setup(struct device *dev, u64 *dma_addr, u64 
>>> *dma_size);
>>> +void acpi_arch_dma_setup(struct device *dev);
>>>   #else
>>>   static inline void
>>>   acpi_numa_gicc_affinity_init(struct acpi_srat_gicc_affinity *pa) { }
>>>   static inline void
>>> -acpi_arch_dma_setup(struct device *dev, u64 *dma_addr, u64 
>>> *dma_size) { }
>>> +acpi_arch_dma_setup(struct device *dev) { }
>>>   #endif
>>>   int acpi_numa_memory_affinity_init (struct acpi_srat_mem_affinity 
>>> *ma);
>>> @@ -977,8 +977,7 @@ static inline enum dev_dma_attr 
>>> acpi_get_dma_attr(struct acpi_device *adev)
>>>       return DEV_DMA_NOT_SUPPORTED;
>>>   }
>>> -static inline int acpi_dma_get_range(struct device *dev, u64 *dma_addr,
>>> -                     u64 *offset, u64 *size)
>>> +static inline int acpi_dma_get_range(struct device *dev, const 
>>> struct bus_dma_region **map)
>>>   {
>>>       return -ENODEV;
>>>   }
>>> -- 
>>> 2.31.1
>>>