Messages in this thread | | | Subject | Re: [PATCH V2 1/2] ACPI / scan: Support multiple dma windows with different offsets | From | Jianmin Lv <> | Date | Sat, 6 Aug 2022 14:13:12 +0800 |
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On 2022/8/5 下午8:46, Robin Murphy wrote: > On 2022-08-05 08:31, 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, and pass 0 and >> U64_MAX for dma_base and size of arch_setup_dma_ops. > > Hmm, I realise the reasoning behind this exists largely in my head, so > for the benefit of everyone else we should perhaps clarify that these > arguments are now redundant, so this is a simplification consistent with > what other ACPI architectures also pass to iommu_setup_dma_ops(). >
Ok, I'll add reason of changing it into commit log for everyone else.
>> Signed-off-by: Jianmin Lv <lvjianmin@loongson.cn> >> --- >> drivers/acpi/arm64/dma.c | 44 >> +++++++++++++++++++++++++++++++++----------- >> drivers/acpi/scan.c | 48 >> ++++++++++++++++++++++++------------------------ >> include/acpi/acpi_bus.h | 3 +-- >> include/linux/acpi.h | 7 +++---- >> 4 files changed, 61 insertions(+), 41 deletions(-) >> >> diff --git a/drivers/acpi/arm64/dma.c b/drivers/acpi/arm64/dma.c >> index f16739a..64a41b2 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 >> @@ -26,7 +27,33 @@ 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) { >> + const struct bus_dma_region *r = map; >> + u64 dma_start, dma_end = 0; >> + >> + /* determine the overall bounds of all dma regions */ >> + for (dma_start = U64_MAX; r->size; r++) { >> + >> + /* Take lower and upper limits */ >> + if (r->dma_start < dma_start) >> + dma_start = r->dma_start; > > dma_start now only serves as an overcomplicated way to tell if the list > was empty, so we don't need it...
Ok,thanks.
> >> + if (r->dma_start + r->size - 1 > dma_end) >> + dma_end = r->dma_start + r->size - 1; >> + } >> + >> + if (dma_start >= dma_end) { >> + dev_dbg(dev, "Invalid DMA regions configuration\n"); >> + return; > > ...but we also don't need this check anway - either there was at least > one valid resource, so dma_end is now set to something sensible, or > there were none, in which case the implementation of > acpi_dma_get_range() here returns success while leaving map == NULL, so > we've already crashed dereferencing r->size. >
Ok, thanks.
>> + } >> + >> + mask = DMA_BIT_MASK(ilog2(dma_end) + 1); >> + dev->bus_dma_limit = dma_end; >> + dev->dma_range_map = map; >> + dev->coherent_dma_mask = min(dev->coherent_dma_mask, mask); >> + *dev->dma_mask = min(*dev->dma_mask, mask); > > Don't duplicate all this, just set "size = dma_end + 1" so the existing > code below picks it up. >
TBH, I'm not familiar with ARM64's DMA stuff, but from the code here, I think there are two ways to get dma ranges: acpi_dma_get_range or iort_dma_get_ranges.
Before the patch, after obtaining the dmaaddr, offset and size in any way of the both, the bus_dma_limit, mask and dma_range_map will be initialized, and dma_range_map is created a *new* one for *both* ways.
But after changing acpi_dma_get_range, when we are ok to obtain dma_range_map by acpi_dma_get_range, we'll use it instead of creating a new one like before. For iort_dma_get_ranges, we have to still create a new dma_range_map. So, I have to handle separately each way here.
It seems that it's enough to handle dma_range_map separately, and others can be still initialized in one place.
>> + } >> + >> if (ret == -ENODEV) >> ret = iort_dma_get_ranges(dev, &size); >> if (!ret) { >> @@ -34,17 +61,12 @@ void acpi_arch_dma_setup(struct device *dev, u64 >> *dma_addr, u64 *dma_size) >> * 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!" >> : ""); >> + ret = dma_direct_set_offset(dev, 0, 0, size); > > Don't call this - we're setting dev->dma_range_map now, so it will only > scream and fail (or do nothing if there's no offset). >
Same as above.
>> + } >> } >> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c >> index 762b61f..736517e 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" >> @@ -1492,15 +1493,15 @@ enum dev_dma_attr acpi_get_dma_attr(struct >> acpi_device *adev) >> * >> * Return 0 on success, < 0 on failure. >> */ > > Don't forget to update the kerneldoc as well. >
Ok, thanks.
>> -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; >> + int num_ranges = 0; >> + struct bus_dma_region *r; >> /* >> * Walk the device tree chasing an ACPI companion with a _DMA >> @@ -1525,31 +1526,31 @@ int acpi_dma_get_range(struct device *dev, u64 >> *dma_addr, u64 *offset, >> ret = acpi_dev_get_dma_resources(adev, &list); >> if (ret > 0) { >> + list_for_each_entry(rentry, &list, node) >> + num_ranges++; > > We already have the number of resources in ret. >
Ok, thanks.
> Looking at this, I also now wonder if we're doing the right thing if the > object is present but contains no resources. The spec isn't clear > whether that's even really valid, but if it is, is it meaningful? It > seems we'd currently consider an empty object equivalent to no object, > but if anything it should perhaps be interpreted as the opposite, i.e. > that no DMA is possible because the bus does not decode any ranges. Is > anyone more familiar with the intent of the spec here? > > Thanks, > Robin. >
According to _DMA of ACPI spec, _DMA is optional, if without it(no _DMA object configured in DSDT), kernel assumes that any address range placed on bus by a child device is valid and can be decoded. So I think it is still legal if _DMA is present and no resources contained in it. I mean an empty _DMA object equals no _DMA object. But obviously it's not meaningful for an empty _DMA object, anybody should not pass an empty _DMA object.
>> + >> + r = kcalloc(num_ranges + 1, sizeof(*r), GFP_KERNEL); >> + if (!r) { >> + ret = -ENOMEM; >> + goto out; >> + } >> + >> + *map = r; >> + >> 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 = rentry->res->end - rentry->res->start + 1; >> + 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); >> @@ -1639,20 +1640,19 @@ 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 0dc1ea0b..e106073 100644 >> --- a/include/acpi/acpi_bus.h >> +++ b/include/acpi/acpi_bus.h >> @@ -611,8 +611,7 @@ struct acpi_pci_root { >> 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 44975c1..34e0545 100644 >> --- a/include/linux/acpi.h >> +++ b/include/linux/acpi.h >> @@ -280,12 +280,12 @@ int acpi_table_parse_madt(enum acpi_madt_type id, >> #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); >> @@ -974,8 +974,7 @@ 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; >> }
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