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Message-ID: <27a66424-472e-0709-a46f-74b401bca342@codeaurora.org>
Date: Tue, 23 May 2017 14:29:05 +0530
From: Sricharan R <sricharan@...eaurora.org>
To: Nate Watterson <nwatters@...eaurora.org>, robin.murphy@....com,
will.deacon@....com, joro@...tes.org, lorenzo.pieralisi@....com,
iommu@...ts.linux-foundation.org,
linux-arm-kernel@...ts.infradead.org,
linux-arm-msm@...r.kernel.org, m.szyprowski@...sung.com,
bhelgaas@...gle.com, linux-pci@...r.kernel.org,
linux-acpi@...r.kernel.org, tn@...ihalf.com, hanjun.guo@...aro.org,
okaya@...eaurora.org, robh+dt@...nel.org, frowand.list@...il.com,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
sudeep.holla@....com, rjw@...ysocki.net, lenb@...nel.org,
catalin.marinas@....com, arnd@...db.de, linux-arch@...r.kernel.org,
gregkh@...uxfoundation.org
Subject: Re: [PATCH V11 08/11] drivers: acpi: Handle IOMMU lookup failure with
deferred probing or error
Hi,
On 5/23/2017 11:56 AM, Nate Watterson wrote:
> Hi Sricharan,
>
> On 4/10/2017 7:21 AM, Sricharan R wrote:
>> This is an equivalent to the DT's handling of the iommu master's probe
>> with deferred probing when the corrsponding iommu is not probed yet.
>> The lack of a registered IOMMU can be caused by the lack of a driver for
>> the IOMMU, the IOMMU device probe not having been performed yet, having
>> been deferred, or having failed.
>>
>> The first case occurs when the firmware describes the bus master and
>> IOMMU topology correctly but no device driver exists for the IOMMU yet
>> or the device driver has not been compiled in. Return NULL, the caller
>> will configure the device without an IOMMU.
>>
>> The second and third cases are handled by deferring the probe of the bus
>> master device which will eventually get reprobed after the IOMMU.
>>
>> The last case is currently handled by deferring the probe of the bus
>> master device as well. A mechanism to either configure the bus master
>> device without an IOMMU or to fail the bus master device probe depending
>> on whether the IOMMU is optional or mandatory would be a good
>> enhancement.
>>
>> Tested-by: Hanjun Guo <hanjun.guo@...aro.org>
>> Reviewed-by: Robin Murphy <robin.murphy@....com>
>> [Lorenzo: Added fixes for dma_coherent_mask overflow, acpi_dma_configure
>> called multiple times for same device]
>> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
>> Signed-off-by: Sricharan R <sricharan@...eaurora.org>
>> ---
>> drivers/acpi/arm64/iort.c | 33 ++++++++++++++++++++++++++++++++-
>> drivers/acpi/scan.c | 11 ++++++++---
>> drivers/base/dma-mapping.c | 2 +-
>> include/acpi/acpi_bus.h | 2 +-
>> include/linux/acpi.h | 7 +++++--
>> 5 files changed, 47 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
>> index 3dd9ec3..e323ece 100644
>> --- a/drivers/acpi/arm64/iort.c
>> +++ b/drivers/acpi/arm64/iort.c
>> @@ -543,6 +543,14 @@ static const struct iommu_ops *iort_iommu_xlate(struct device *dev,
>> const struct iommu_ops *ops = NULL;
>> int ret = -ENODEV;
>> struct fwnode_handle *iort_fwnode;
>> + struct iommu_fwspec *fwspec = dev->iommu_fwspec;
>> +
>> + /*
>> + * If we already translated the fwspec there
>> + * is nothing left to do, return the iommu_ops.
>> + */
>> + if (fwspec && fwspec->ops)
>> + return fwspec->ops;
>
> Is this logic strictly required? It breaks masters with multiple SIDs
> as only the first SID is actually added to the master's fwspec.
>
The logic here is same as what is done in DT, in of_iommu_configure.
This is to pullback the iommu_ops that was set for the device from the
previous run. (when the device probe is deferred and called again).
Infact this piece of hunk was initially missing in ACPI, later added
since a bug was reported [1] on V9 and then this came in as a fix in V10.
But looks like this check should be in iort_iommu_configure.
Lorenzo, is that correct ?
[1] https://www.spinics.net/lists/arm-kernel/msg572069.html
If yes i will add this in the fixes that i have already posted.
Regards,
Sricharan
>> if (node) {
>> iort_fwnode = iort_get_fwnode(node);
>> @@ -550,8 +558,17 @@ static const struct iommu_ops *iort_iommu_xlate(struct device *dev,
>> return NULL;
>> ops = iommu_ops_from_fwnode(iort_fwnode);
>> + /*
>> + * If the ops look-up fails, this means that either
>> + * the SMMU drivers have not been probed yet or that
>> + * the SMMU drivers are not built in the kernel;
>> + * Depending on whether the SMMU drivers are built-in
>> + * in the kernel or not, defer the IOMMU configuration
>> + * or just abort it.
>> + */
>> if (!ops)
>> - return NULL;
>> + return iort_iommu_driver_enabled(node->type) ?
>> + ERR_PTR(-EPROBE_DEFER) : NULL;
>> ret = arm_smmu_iort_xlate(dev, streamid, iort_fwnode, ops);
>> }
>> @@ -625,12 +642,26 @@ const struct iommu_ops *iort_iommu_configure(struct device *dev)
>> while (parent) {
>> ops = iort_iommu_xlate(dev, parent, streamid);
>> + if (IS_ERR_OR_NULL(ops))
>> + return ops;
>> parent = iort_node_get_id(node, &streamid,
>> IORT_IOMMU_TYPE, i++);
>> }
>> }
>> + /*
>> + * If we have reason to believe the IOMMU driver missed the initial
>> + * add_device callback for dev, replay it to get things in order.
>> + */
>> + if (!IS_ERR_OR_NULL(ops) && ops->add_device &&
>> + dev->bus && !dev->iommu_group) {
>> + int err = ops->add_device(dev);
>> +
>> + if (err)
>> + ops = ERR_PTR(err);
>> + }
>> +
>> return ops;
>> }
>> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
>> index 1926918..2a513cc 100644
>> --- a/drivers/acpi/scan.c
>> +++ b/drivers/acpi/scan.c
>> @@ -1373,20 +1373,25 @@ enum dev_dma_attr acpi_get_dma_attr(struct acpi_device *adev)
>> * @dev: The pointer to the device
>> * @attr: device dma attributes
>> */
>> -void acpi_dma_configure(struct device *dev, enum dev_dma_attr attr)
>> +int acpi_dma_configure(struct device *dev, enum dev_dma_attr attr)
>> {
>> const struct iommu_ops *iommu;
>> + u64 size;
>> iort_set_dma_mask(dev);
>> iommu = iort_iommu_configure(dev);
>> + if (IS_ERR(iommu))
>> + return PTR_ERR(iommu);
>> + size = max(dev->coherent_dma_mask, dev->coherent_dma_mask + 1);
>> /*
>> * Assume dma valid range starts at 0 and covers the whole
>> * coherent_dma_mask.
>> */
>> - arch_setup_dma_ops(dev, 0, dev->coherent_dma_mask + 1, iommu,
>> - attr == DEV_DMA_COHERENT);
>> + arch_setup_dma_ops(dev, 0, size, iommu, attr == DEV_DMA_COHERENT);
>> +
>> + return 0;
>> }
>> EXPORT_SYMBOL_GPL(acpi_dma_configure);
>> diff --git a/drivers/base/dma-mapping.c b/drivers/base/dma-mapping.c
>> index 82bd45c..755a2b5 100644
>> --- a/drivers/base/dma-mapping.c
>> +++ b/drivers/base/dma-mapping.c
>> @@ -368,7 +368,7 @@ int dma_configure(struct device *dev)
>> } else if (has_acpi_companion(dma_dev)) {
>> attr = acpi_get_dma_attr(to_acpi_device_node(dma_dev->fwnode));
>> if (attr != DEV_DMA_NOT_SUPPORTED)
>> - acpi_dma_configure(dev, attr);
>> + ret = acpi_dma_configure(dev, attr);
>> }
>> if (bridge)
>> diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
>> index ef0ae8a..2a9a5de 100644
>> --- a/include/acpi/acpi_bus.h
>> +++ b/include/acpi/acpi_bus.h
>> @@ -575,7 +575,7 @@ struct acpi_pci_root {
>> bool acpi_dma_supported(struct acpi_device *adev);
>> enum dev_dma_attr acpi_get_dma_attr(struct acpi_device *adev);
>> -void acpi_dma_configure(struct device *dev, enum dev_dma_attr attr);
>> +int acpi_dma_configure(struct device *dev, enum dev_dma_attr attr);
>> void acpi_dma_deconfigure(struct device *dev);
>> struct acpi_device *acpi_find_child_device(struct acpi_device *parent,
>> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
>> index 9b05886..79d06ef6 100644
>> --- a/include/linux/acpi.h
>> +++ b/include/linux/acpi.h
>> @@ -762,8 +762,11 @@ static inline enum dev_dma_attr acpi_get_dma_attr(struct acpi_device *adev)
>> return DEV_DMA_NOT_SUPPORTED;
>> }
>> -static inline void acpi_dma_configure(struct device *dev,
>> - enum dev_dma_attr attr) { }
>> +static inline int acpi_dma_configure(struct device *dev,
>> + enum dev_dma_attr attr)
>> +{
>> + return 0;
>> +}
>> static inline void acpi_dma_deconfigure(struct device *dev) { }
>>
>
--
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