[PATCH] ACPI/IORT: Support address size limit for root complexes

[PATCH] ACPI/IORT: Support address size limit for root complexes

[Robin Murphy]

IORT revision D allows PCI root complex nodes to specify a memory
address size limit equivalently to named components, to help describe
straightforward integrations which don't really warrant a full-blown
_DMA method. Now that our headers are up-to-date, plumb it in.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
---
 drivers/acpi/arm64/iort.c | 25 +++++++++++++++++++++++--
 1 file changed, 23 insertions(+), 2 deletions(-)

diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
index 7a3a541046ed..4a66896e2aa3 100644
--- a/drivers/acpi/arm64/iort.c
+++ b/drivers/acpi/arm64/iort.c
@@ -947,6 +947,24 @@ static int nc_dma_get_range(struct device *dev, u64 *size)
 	return 0;
 }
 
+static int rc_dma_get_range(struct device *dev, u64 *size)
+{
+	struct acpi_iort_node *node;
+	struct acpi_iort_root_complex *rc;
+
+	node = iort_scan_node(ACPI_IORT_NODE_PCI_ROOT_COMPLEX,
+			      iort_match_node_callback, dev);
+	if (!node || node->revision < 1)
+		return -ENODEV;
+
+	rc = (struct acpi_iort_root_complex *)node->node_data;
+
+	*size = rc->memory_address_limit >= 64 ? U64_MAX :
+			1ULL<<rc->memory_address_limit;
+
+	return 0;
+}
+
 /**
  * iort_dma_setup() - Set-up device DMA parameters.
  *
@@ -975,10 +993,13 @@ void iort_dma_setup(struct device *dev, u64 *dma_addr, u64 *dma_size)
 
 	size = max(dev->coherent_dma_mask, dev->coherent_dma_mask + 1);
 
-	if (dev_is_pci(dev))
+	if (dev_is_pci(dev)) {
 		ret = acpi_dma_get_range(dev, &dmaaddr, &offset, &size);
-	else
+		if (ret == -ENODEV)
+			ret = rc_dma_get_range(dev, &size);
+	} else {
 		ret = nc_dma_get_range(dev, &size);
+	}
 
 	if (!ret) {
 		msb = fls64(dmaaddr + size - 1);
-- 
2.17.1.dirty

[PATCH] ACPI/IORT: Support address size limit for root complexes

[Robin Murphy]

IORT revision D allows PCI root complex nodes to specify a memory
address size limit equivalently to named components, to help describe
straightforward integrations which don't really warrant a full-blown
_DMA method. Now that our headers are up-to-date, plumb it in.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
---
 drivers/acpi/arm64/iort.c | 25 +++++++++++++++++++++++--
 1 file changed, 23 insertions(+), 2 deletions(-)

diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
index 7a3a541046ed..4a66896e2aa3 100644
--- a/drivers/acpi/arm64/iort.c
+++ b/drivers/acpi/arm64/iort.c
@@ -947,6 +947,24 @@ static int nc_dma_get_range(struct device *dev, u64 *size)
 	return 0;
 }
 
+static int rc_dma_get_range(struct device *dev, u64 *size)
+{
+	struct acpi_iort_node *node;
+	struct acpi_iort_root_complex *rc;
+
+	node = iort_scan_node(ACPI_IORT_NODE_PCI_ROOT_COMPLEX,
+			      iort_match_node_callback, dev);
+	if (!node || node->revision < 1)
+		return -ENODEV;
+
+	rc = (struct acpi_iort_root_complex *)node->node_data;
+
+	*size = rc->memory_address_limit >= 64 ? U64_MAX :
+			1ULL<<rc->memory_address_limit;
+
+	return 0;
+}
+
 /**
  * iort_dma_setup() - Set-up device DMA parameters.
  *
@@ -975,10 +993,13 @@ void iort_dma_setup(struct device *dev, u64 *dma_addr, u64 *dma_size)
 
 	size = max(dev->coherent_dma_mask, dev->coherent_dma_mask + 1);
 
-	if (dev_is_pci(dev))
+	if (dev_is_pci(dev)) {
 		ret = acpi_dma_get_range(dev, &dmaaddr, &offset, &size);
-	else
+		if (ret == -ENODEV)
+			ret = rc_dma_get_range(dev, &size);
+	} else {
 		ret = nc_dma_get_range(dev, &size);
+	}
 
 	if (!ret) {
 		msb = fls64(dmaaddr + size - 1);
-- 
2.17.1.dirty

Re: [PATCH] ACPI/IORT: Support address size limit for root complexes

[Lorenzo Pieralisi]

On Tue, Jul 10, 2018 at 05:13:45PM +0100, Robin Murphy wrote:
> IORT revision D allows PCI root complex nodes to specify a memory
> address size limit equivalently to named components, to help describe
> straightforward integrations which don't really warrant a full-blown
> _DMA method. Now that our headers are up-to-date, plumb it in.
> 
> Signed-off-by: Robin Murphy <robin.murphy@arm.com>
> ---
>  drivers/acpi/arm64/iort.c | 25 +++++++++++++++++++++++--
>  1 file changed, 23 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
> index 7a3a541046ed..4a66896e2aa3 100644
> --- a/drivers/acpi/arm64/iort.c
> +++ b/drivers/acpi/arm64/iort.c
> @@ -947,6 +947,24 @@ static int nc_dma_get_range(struct device *dev, u64 *size)
>  	return 0;
>  }
>  
> +static int rc_dma_get_range(struct device *dev, u64 *size)
> +{
> +	struct acpi_iort_node *node;
> +	struct acpi_iort_root_complex *rc;
> +
> +	node = iort_scan_node(ACPI_IORT_NODE_PCI_ROOT_COMPLEX,
> +			      iort_match_node_callback, dev);
> +	if (!node || node->revision < 1)
> +		return -ENODEV;
> +
> +	rc = (struct acpi_iort_root_complex *)node->node_data;
> +
> +	*size = rc->memory_address_limit >= 64 ? U64_MAX :
> +			1ULL<<rc->memory_address_limit;
> +
> +	return 0;
> +}
> +
>  /**
>   * iort_dma_setup() - Set-up device DMA parameters.
>   *
> @@ -975,10 +993,13 @@ void iort_dma_setup(struct device *dev, u64 *dma_addr, u64 *dma_size)
>  
>  	size = max(dev->coherent_dma_mask, dev->coherent_dma_mask + 1);
>  
> -	if (dev_is_pci(dev))
> +	if (dev_is_pci(dev)) {
>  		ret = acpi_dma_get_range(dev, &dmaaddr, &offset, &size);
> -	else
> +		if (ret == -ENODEV)
> +			ret = rc_dma_get_range(dev, &size);

Thank you for putting together the patch.

The question is whether it is OK to ignore the IORT address limits
when _DMA is actually specified. It is a sort of grey area that
has to be clarified, maybe we can add a check to detect a size
mismatch, I do not know if something should be added at IORT spec
level to clarify its relation to the _DMA object, if present.

Thanks,
Lorenzo

> +	} else {
>  		ret = nc_dma_get_range(dev, &size);
> +	}
>  
>  	if (!ret) {
>  		msb = fls64(dmaaddr + size - 1);
> -- 
> 2.17.1.dirty
> 

[PATCH] ACPI/IORT: Support address size limit for root complexes

[Lorenzo Pieralisi]

On Tue, Jul 10, 2018 at 05:13:45PM +0100, Robin Murphy wrote:
> IORT revision D allows PCI root complex nodes to specify a memory
> address size limit equivalently to named components, to help describe
> straightforward integrations which don't really warrant a full-blown
> _DMA method. Now that our headers are up-to-date, plumb it in.
> 
> Signed-off-by: Robin Murphy <robin.murphy@arm.com>
> ---
>  drivers/acpi/arm64/iort.c | 25 +++++++++++++++++++++++--
>  1 file changed, 23 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
> index 7a3a541046ed..4a66896e2aa3 100644
> --- a/drivers/acpi/arm64/iort.c
> +++ b/drivers/acpi/arm64/iort.c
> @@ -947,6 +947,24 @@ static int nc_dma_get_range(struct device *dev, u64 *size)
>  	return 0;
>  }
>  
> +static int rc_dma_get_range(struct device *dev, u64 *size)
> +{
> +	struct acpi_iort_node *node;
> +	struct acpi_iort_root_complex *rc;
> +
> +	node = iort_scan_node(ACPI_IORT_NODE_PCI_ROOT_COMPLEX,
> +			      iort_match_node_callback, dev);
> +	if (!node || node->revision < 1)
> +		return -ENODEV;
> +
> +	rc = (struct acpi_iort_root_complex *)node->node_data;
> +
> +	*size = rc->memory_address_limit >= 64 ? U64_MAX :
> +			1ULL<<rc->memory_address_limit;
> +
> +	return 0;
> +}
> +
>  /**
>   * iort_dma_setup() - Set-up device DMA parameters.
>   *
> @@ -975,10 +993,13 @@ void iort_dma_setup(struct device *dev, u64 *dma_addr, u64 *dma_size)
>  
>  	size = max(dev->coherent_dma_mask, dev->coherent_dma_mask + 1);
>  
> -	if (dev_is_pci(dev))
> +	if (dev_is_pci(dev)) {
>  		ret = acpi_dma_get_range(dev, &dmaaddr, &offset, &size);
> -	else
> +		if (ret == -ENODEV)
> +			ret = rc_dma_get_range(dev, &size);

Thank you for putting together the patch.

The question is whether it is OK to ignore the IORT address limits
when _DMA is actually specified. It is a sort of grey area that
has to be clarified, maybe we can add a check to detect a size
mismatch, I do not know if something should be added at IORT spec
level to clarify its relation to the _DMA object, if present.

Thanks,
Lorenzo

> +	} else {
>  		ret = nc_dma_get_range(dev, &size);
> +	}
>  
>  	if (!ret) {
>  		msb = fls64(dmaaddr + size - 1);
> -- 
> 2.17.1.dirty
> 

Re: [PATCH] ACPI/IORT: Support address size limit for root complexes

[Robin Murphy]

On 2018-07-16 4:10 PM, Lorenzo Pieralisi wrote:
> On Tue, Jul 10, 2018 at 05:13:45PM +0100, Robin Murphy wrote:
>> IORT revision D allows PCI root complex nodes to specify a memory
>> address size limit equivalently to named components, to help describe
>> straightforward integrations which don't really warrant a full-blown
>> _DMA method. Now that our headers are up-to-date, plumb it in.
>>
>> Signed-off-by: Robin Murphy <robin.murphy@arm.com>
>> ---
>>   drivers/acpi/arm64/iort.c | 25 +++++++++++++++++++++++--
>>   1 file changed, 23 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
>> index 7a3a541046ed..4a66896e2aa3 100644
>> --- a/drivers/acpi/arm64/iort.c
>> +++ b/drivers/acpi/arm64/iort.c
>> @@ -947,6 +947,24 @@ static int nc_dma_get_range(struct device *dev, u64 *size)
>>   	return 0;
>>   }
>>   
>> +static int rc_dma_get_range(struct device *dev, u64 *size)
>> +{
>> +	struct acpi_iort_node *node;
>> +	struct acpi_iort_root_complex *rc;
>> +
>> +	node = iort_scan_node(ACPI_IORT_NODE_PCI_ROOT_COMPLEX,
>> +			      iort_match_node_callback, dev);
>> +	if (!node || node->revision < 1)
>> +		return -ENODEV;
>> +
>> +	rc = (struct acpi_iort_root_complex *)node->node_data;
>> +
>> +	*size = rc->memory_address_limit >= 64 ? U64_MAX :
>> +			1ULL<<rc->memory_address_limit;
>> +
>> +	return 0;
>> +}
>> +
>>   /**
>>    * iort_dma_setup() - Set-up device DMA parameters.
>>    *
>> @@ -975,10 +993,13 @@ void iort_dma_setup(struct device *dev, u64 *dma_addr, u64 *dma_size)
>>   
>>   	size = max(dev->coherent_dma_mask, dev->coherent_dma_mask + 1);
>>   
>> -	if (dev_is_pci(dev))
>> +	if (dev_is_pci(dev)) {
>>   		ret = acpi_dma_get_range(dev, &dmaaddr, &offset, &size);
>> -	else
>> +		if (ret == -ENODEV)
>> +			ret = rc_dma_get_range(dev, &size);
> 
> Thank you for putting together the patch.
> 
> The question is whether it is OK to ignore the IORT address limits
> when _DMA is actually specified. It is a sort of grey area that
> has to be clarified, maybe we can add a check to detect a size
> mismatch, I do not know if something should be added at IORT spec
> level to clarify its relation to the _DMA object, if present.

Yeah, I'm assuming that _DMA would be used to describe conditions more 
specific than the simple address size limit (i.e. bridge windows), so 
even if both are present, the range inferred from _DMA will always be 
less than or equal to that inferred from IORT, and thus rather than 
explicitly calculating the intersection of the two we can simply do this 
short-circuit.

If IORT accurately reflects the total number of usable address bits, 
then I can't see that it would ever make sense for _DMA to specify an 
address range which exceeds that; I guess it comes down to how much 
effort we want to spend verifying firmware instead of trusting it.

Robin.

[PATCH] ACPI/IORT: Support address size limit for root complexes

[Robin Murphy]

On 2018-07-16 4:10 PM, Lorenzo Pieralisi wrote:
> On Tue, Jul 10, 2018 at 05:13:45PM +0100, Robin Murphy wrote:
>> IORT revision D allows PCI root complex nodes to specify a memory
>> address size limit equivalently to named components, to help describe
>> straightforward integrations which don't really warrant a full-blown
>> _DMA method. Now that our headers are up-to-date, plumb it in.
>>
>> Signed-off-by: Robin Murphy <robin.murphy@arm.com>
>> ---
>>   drivers/acpi/arm64/iort.c | 25 +++++++++++++++++++++++--
>>   1 file changed, 23 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
>> index 7a3a541046ed..4a66896e2aa3 100644
>> --- a/drivers/acpi/arm64/iort.c
>> +++ b/drivers/acpi/arm64/iort.c
>> @@ -947,6 +947,24 @@ static int nc_dma_get_range(struct device *dev, u64 *size)
>>   	return 0;
>>   }
>>   
>> +static int rc_dma_get_range(struct device *dev, u64 *size)
>> +{
>> +	struct acpi_iort_node *node;
>> +	struct acpi_iort_root_complex *rc;
>> +
>> +	node = iort_scan_node(ACPI_IORT_NODE_PCI_ROOT_COMPLEX,
>> +			      iort_match_node_callback, dev);
>> +	if (!node || node->revision < 1)
>> +		return -ENODEV;
>> +
>> +	rc = (struct acpi_iort_root_complex *)node->node_data;
>> +
>> +	*size = rc->memory_address_limit >= 64 ? U64_MAX :
>> +			1ULL<<rc->memory_address_limit;
>> +
>> +	return 0;
>> +}
>> +
>>   /**
>>    * iort_dma_setup() - Set-up device DMA parameters.
>>    *
>> @@ -975,10 +993,13 @@ void iort_dma_setup(struct device *dev, u64 *dma_addr, u64 *dma_size)
>>   
>>   	size = max(dev->coherent_dma_mask, dev->coherent_dma_mask + 1);
>>   
>> -	if (dev_is_pci(dev))
>> +	if (dev_is_pci(dev)) {
>>   		ret = acpi_dma_get_range(dev, &dmaaddr, &offset, &size);
>> -	else
>> +		if (ret == -ENODEV)
>> +			ret = rc_dma_get_range(dev, &size);
> 
> Thank you for putting together the patch.
> 
> The question is whether it is OK to ignore the IORT address limits
> when _DMA is actually specified. It is a sort of grey area that
> has to be clarified, maybe we can add a check to detect a size
> mismatch, I do not know if something should be added at IORT spec
> level to clarify its relation to the _DMA object, if present.

Yeah, I'm assuming that _DMA would be used to describe conditions more 
specific than the simple address size limit (i.e. bridge windows), so 
even if both are present, the range inferred from _DMA will always be 
less than or equal to that inferred from IORT, and thus rather than 
explicitly calculating the intersection of the two we can simply do this 
short-circuit.

If IORT accurately reflects the total number of usable address bits, 
then I can't see that it would ever make sense for _DMA to specify an 
address range which exceeds that; I guess it comes down to how much 
effort we want to spend verifying firmware instead of trusting it.

Robin.

Re: [PATCH] ACPI/IORT: Support address size limit for root complexes

[Lorenzo Pieralisi]

[+Catalin, Will]

On Mon, Jul 16, 2018 at 04:34:51PM +0100, Robin Murphy wrote:
> On 2018-07-16 4:10 PM, Lorenzo Pieralisi wrote:
> >On Tue, Jul 10, 2018 at 05:13:45PM +0100, Robin Murphy wrote:
> >>IORT revision D allows PCI root complex nodes to specify a memory
> >>address size limit equivalently to named components, to help describe
> >>straightforward integrations which don't really warrant a full-blown
> >>_DMA method. Now that our headers are up-to-date, plumb it in.
> >>
> >>Signed-off-by: Robin Murphy <robin.murphy@arm.com>
> >>---
> >>  drivers/acpi/arm64/iort.c | 25 +++++++++++++++++++++++--
> >>  1 file changed, 23 insertions(+), 2 deletions(-)
> >>
> >>diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
> >>index 7a3a541046ed..4a66896e2aa3 100644
> >>--- a/drivers/acpi/arm64/iort.c
> >>+++ b/drivers/acpi/arm64/iort.c
> >>@@ -947,6 +947,24 @@ static int nc_dma_get_range(struct device *dev, u64 *size)
> >>  	return 0;
> >>  }
> >>+static int rc_dma_get_range(struct device *dev, u64 *size)
> >>+{
> >>+	struct acpi_iort_node *node;
> >>+	struct acpi_iort_root_complex *rc;
> >>+
> >>+	node = iort_scan_node(ACPI_IORT_NODE_PCI_ROOT_COMPLEX,
> >>+			      iort_match_node_callback, dev);
> >>+	if (!node || node->revision < 1)
> >>+		return -ENODEV;
> >>+
> >>+	rc = (struct acpi_iort_root_complex *)node->node_data;
> >>+
> >>+	*size = rc->memory_address_limit >= 64 ? U64_MAX :
> >>+			1ULL<<rc->memory_address_limit;
> >>+
> >>+	return 0;
> >>+}
> >>+
> >>  /**
> >>   * iort_dma_setup() - Set-up device DMA parameters.
> >>   *
> >>@@ -975,10 +993,13 @@ void iort_dma_setup(struct device *dev, u64 *dma_addr, u64 *dma_size)
> >>  	size = max(dev->coherent_dma_mask, dev->coherent_dma_mask + 1);
> >>-	if (dev_is_pci(dev))
> >>+	if (dev_is_pci(dev)) {
> >>  		ret = acpi_dma_get_range(dev, &dmaaddr, &offset, &size);
> >>-	else
> >>+		if (ret == -ENODEV)
> >>+			ret = rc_dma_get_range(dev, &size);
> >
> >Thank you for putting together the patch.
> >
> >The question is whether it is OK to ignore the IORT address limits
> >when _DMA is actually specified. It is a sort of grey area that
> >has to be clarified, maybe we can add a check to detect a size
> >mismatch, I do not know if something should be added at IORT spec
> >level to clarify its relation to the _DMA object, if present.
> 
> Yeah, I'm assuming that _DMA would be used to describe conditions
> more specific than the simple address size limit (i.e. bridge
> windows), so even if both are present, the range inferred from _DMA
> will always be less than or equal to that inferred from IORT, and
> thus rather than explicitly calculating the intersection of the two
> we can simply do this short-circuit.
> 
> If IORT accurately reflects the total number of usable address bits,
> then I can't see that it would ever make sense for _DMA to specify
> an address range which exceeds that; I guess it comes down to how
> much effort we want to spend verifying firmware instead of trusting
> it.

I agree with this reasoning and the patch looks fine, I have not
queued anything for this cycle for IORT so I would ask Will/Catalin
to pick it up (if we still have time for v4.19):

Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>

[PATCH] ACPI/IORT: Support address size limit for root complexes

[Lorenzo Pieralisi]

[+Catalin, Will]

On Mon, Jul 16, 2018 at 04:34:51PM +0100, Robin Murphy wrote:
> On 2018-07-16 4:10 PM, Lorenzo Pieralisi wrote:
> >On Tue, Jul 10, 2018 at 05:13:45PM +0100, Robin Murphy wrote:
> >>IORT revision D allows PCI root complex nodes to specify a memory
> >>address size limit equivalently to named components, to help describe
> >>straightforward integrations which don't really warrant a full-blown
> >>_DMA method. Now that our headers are up-to-date, plumb it in.
> >>
> >>Signed-off-by: Robin Murphy <robin.murphy@arm.com>
> >>---
> >>  drivers/acpi/arm64/iort.c | 25 +++++++++++++++++++++++--
> >>  1 file changed, 23 insertions(+), 2 deletions(-)
> >>
> >>diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
> >>index 7a3a541046ed..4a66896e2aa3 100644
> >>--- a/drivers/acpi/arm64/iort.c
> >>+++ b/drivers/acpi/arm64/iort.c
> >>@@ -947,6 +947,24 @@ static int nc_dma_get_range(struct device *dev, u64 *size)
> >>  	return 0;
> >>  }
> >>+static int rc_dma_get_range(struct device *dev, u64 *size)
> >>+{
> >>+	struct acpi_iort_node *node;
> >>+	struct acpi_iort_root_complex *rc;
> >>+
> >>+	node = iort_scan_node(ACPI_IORT_NODE_PCI_ROOT_COMPLEX,
> >>+			      iort_match_node_callback, dev);
> >>+	if (!node || node->revision < 1)
> >>+		return -ENODEV;
> >>+
> >>+	rc = (struct acpi_iort_root_complex *)node->node_data;
> >>+
> >>+	*size = rc->memory_address_limit >= 64 ? U64_MAX :
> >>+			1ULL<<rc->memory_address_limit;
> >>+
> >>+	return 0;
> >>+}
> >>+
> >>  /**
> >>   * iort_dma_setup() - Set-up device DMA parameters.
> >>   *
> >>@@ -975,10 +993,13 @@ void iort_dma_setup(struct device *dev, u64 *dma_addr, u64 *dma_size)
> >>  	size = max(dev->coherent_dma_mask, dev->coherent_dma_mask + 1);
> >>-	if (dev_is_pci(dev))
> >>+	if (dev_is_pci(dev)) {
> >>  		ret = acpi_dma_get_range(dev, &dmaaddr, &offset, &size);
> >>-	else
> >>+		if (ret == -ENODEV)
> >>+			ret = rc_dma_get_range(dev, &size);
> >
> >Thank you for putting together the patch.
> >
> >The question is whether it is OK to ignore the IORT address limits
> >when _DMA is actually specified. It is a sort of grey area that
> >has to be clarified, maybe we can add a check to detect a size
> >mismatch, I do not know if something should be added at IORT spec
> >level to clarify its relation to the _DMA object, if present.
> 
> Yeah, I'm assuming that _DMA would be used to describe conditions
> more specific than the simple address size limit (i.e. bridge
> windows), so even if both are present, the range inferred from _DMA
> will always be less than or equal to that inferred from IORT, and
> thus rather than explicitly calculating the intersection of the two
> we can simply do this short-circuit.
> 
> If IORT accurately reflects the total number of usable address bits,
> then I can't see that it would ever make sense for _DMA to specify
> an address range which exceeds that; I guess it comes down to how
> much effort we want to spend verifying firmware instead of trusting
> it.

I agree with this reasoning and the patch looks fine, I have not
queued anything for this cycle for IORT so I would ask Will/Catalin
to pick it up (if we still have time for v4.19):

Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>

Re: [PATCH] ACPI/IORT: Support address size limit for root complexes

[Hanjun Guo]

On 2018/7/11 0:13, Robin Murphy wrote:
> IORT revision D allows PCI root complex nodes to specify a memory
> address size limit equivalently to named components, to help describe
> straightforward integrations which don't really warrant a full-blown
> _DMA method. Now that our headers are up-to-date, plumb it in.
> 
> Signed-off-by: Robin Murphy <robin.murphy@arm.com>
> ---
>  drivers/acpi/arm64/iort.c | 25 +++++++++++++++++++++++--
>  1 file changed, 23 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
> index 7a3a541046ed..4a66896e2aa3 100644
> --- a/drivers/acpi/arm64/iort.c
> +++ b/drivers/acpi/arm64/iort.c
> @@ -947,6 +947,24 @@ static int nc_dma_get_range(struct device *dev, u64 *size)
>  	return 0;
>  }
>  
> +static int rc_dma_get_range(struct device *dev, u64 *size)
> +{
> +	struct acpi_iort_node *node;
> +	struct acpi_iort_root_complex *rc;
> +
> +	node = iort_scan_node(ACPI_IORT_NODE_PCI_ROOT_COMPLEX,
> +			      iort_match_node_callback, dev);
> +	if (!node || node->revision < 1)
> +		return -ENODEV;
> +
> +	rc = (struct acpi_iort_root_complex *)node->node_data;
> +
> +	*size = rc->memory_address_limit >= 64 ? U64_MAX :
> +			1ULL<<rc->memory_address_limit;
> +
> +	return 0;
> +}
> +
>  /**
>   * iort_dma_setup() - Set-up device DMA parameters.
>   *
> @@ -975,10 +993,13 @@ void iort_dma_setup(struct device *dev, u64 *dma_addr, u64 *dma_size)
>  
>  	size = max(dev->coherent_dma_mask, dev->coherent_dma_mask + 1);
>  
> -	if (dev_is_pci(dev))
> +	if (dev_is_pci(dev)) {
>  		ret = acpi_dma_get_range(dev, &dmaaddr, &offset, &size);
> -	else
> +		if (ret == -ENODEV)
> +			ret = rc_dma_get_range(dev, &size);
> +	} else {
>  		ret = nc_dma_get_range(dev, &size);
> +	}
>  
>  	if (!ret) {
>  		msb = fls64(dmaaddr + size - 1);
> 

Looks good to me,

Reviewed-by: Hanjun Guo <hanjun.guo@linaro.org>

Thanks
Hanjun

[PATCH] ACPI/IORT: Support address size limit for root complexes

[Hanjun Guo]

On 2018/7/11 0:13, Robin Murphy wrote:
> IORT revision D allows PCI root complex nodes to specify a memory
> address size limit equivalently to named components, to help describe
> straightforward integrations which don't really warrant a full-blown
> _DMA method. Now that our headers are up-to-date, plumb it in.
> 
> Signed-off-by: Robin Murphy <robin.murphy@arm.com>
> ---
>  drivers/acpi/arm64/iort.c | 25 +++++++++++++++++++++++--
>  1 file changed, 23 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
> index 7a3a541046ed..4a66896e2aa3 100644
> --- a/drivers/acpi/arm64/iort.c
> +++ b/drivers/acpi/arm64/iort.c
> @@ -947,6 +947,24 @@ static int nc_dma_get_range(struct device *dev, u64 *size)
>  	return 0;
>  }
>  
> +static int rc_dma_get_range(struct device *dev, u64 *size)
> +{
> +	struct acpi_iort_node *node;
> +	struct acpi_iort_root_complex *rc;
> +
> +	node = iort_scan_node(ACPI_IORT_NODE_PCI_ROOT_COMPLEX,
> +			      iort_match_node_callback, dev);
> +	if (!node || node->revision < 1)
> +		return -ENODEV;
> +
> +	rc = (struct acpi_iort_root_complex *)node->node_data;
> +
> +	*size = rc->memory_address_limit >= 64 ? U64_MAX :
> +			1ULL<<rc->memory_address_limit;
> +
> +	return 0;
> +}
> +
>  /**
>   * iort_dma_setup() - Set-up device DMA parameters.
>   *
> @@ -975,10 +993,13 @@ void iort_dma_setup(struct device *dev, u64 *dma_addr, u64 *dma_size)
>  
>  	size = max(dev->coherent_dma_mask, dev->coherent_dma_mask + 1);
>  
> -	if (dev_is_pci(dev))
> +	if (dev_is_pci(dev)) {
>  		ret = acpi_dma_get_range(dev, &dmaaddr, &offset, &size);
> -	else
> +		if (ret == -ENODEV)
> +			ret = rc_dma_get_range(dev, &size);
> +	} else {
>  		ret = nc_dma_get_range(dev, &size);
> +	}
>  
>  	if (!ret) {
>  		msb = fls64(dmaaddr + size - 1);
> 

Looks good to me,

Reviewed-by: Hanjun Guo <hanjun.guo@linaro.org>

Thanks
Hanjun

Re: [PATCH] ACPI/IORT: Support address size limit for root complexes

[Robin Murphy]

[+Christoph]

On 18/07/18 17:36, Lorenzo Pieralisi wrote:
> [+Catalin, Will]
> 
> On Mon, Jul 16, 2018 at 04:34:51PM +0100, Robin Murphy wrote:
>> On 2018-07-16 4:10 PM, Lorenzo Pieralisi wrote:
>>> On Tue, Jul 10, 2018 at 05:13:45PM +0100, Robin Murphy wrote:
>>>> IORT revision D allows PCI root complex nodes to specify a memory
>>>> address size limit equivalently to named components, to help describe
>>>> straightforward integrations which don't really warrant a full-blown
>>>> _DMA method. Now that our headers are up-to-date, plumb it in.
>>>>
>>>> Signed-off-by: Robin Murphy <robin.murphy@arm.com>
>>>> ---
>>>>   drivers/acpi/arm64/iort.c | 25 +++++++++++++++++++++++--
>>>>   1 file changed, 23 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
>>>> index 7a3a541046ed..4a66896e2aa3 100644
>>>> --- a/drivers/acpi/arm64/iort.c
>>>> +++ b/drivers/acpi/arm64/iort.c
>>>> @@ -947,6 +947,24 @@ static int nc_dma_get_range(struct device *dev, u64 *size)
>>>>   	return 0;
>>>>   }
>>>> +static int rc_dma_get_range(struct device *dev, u64 *size)
>>>> +{
>>>> +	struct acpi_iort_node *node;
>>>> +	struct acpi_iort_root_complex *rc;
>>>> +
>>>> +	node = iort_scan_node(ACPI_IORT_NODE_PCI_ROOT_COMPLEX,
>>>> +			      iort_match_node_callback, dev);
>>>> +	if (!node || node->revision < 1)
>>>> +		return -ENODEV;
>>>> +
>>>> +	rc = (struct acpi_iort_root_complex *)node->node_data;
>>>> +
>>>> +	*size = rc->memory_address_limit >= 64 ? U64_MAX :
>>>> +			1ULL<<rc->memory_address_limit;
>>>> +
>>>> +	return 0;
>>>> +}
>>>> +
>>>>   /**
>>>>    * iort_dma_setup() - Set-up device DMA parameters.
>>>>    *
>>>> @@ -975,10 +993,13 @@ void iort_dma_setup(struct device *dev, u64 *dma_addr, u64 *dma_size)
>>>>   	size = max(dev->coherent_dma_mask, dev->coherent_dma_mask + 1);
>>>> -	if (dev_is_pci(dev))
>>>> +	if (dev_is_pci(dev)) {
>>>>   		ret = acpi_dma_get_range(dev, &dmaaddr, &offset, &size);
>>>> -	else
>>>> +		if (ret == -ENODEV)
>>>> +			ret = rc_dma_get_range(dev, &size);
>>>
>>> Thank you for putting together the patch.
>>>
>>> The question is whether it is OK to ignore the IORT address limits
>>> when _DMA is actually specified. It is a sort of grey area that
>>> has to be clarified, maybe we can add a check to detect a size
>>> mismatch, I do not know if something should be added at IORT spec
>>> level to clarify its relation to the _DMA object, if present.
>>
>> Yeah, I'm assuming that _DMA would be used to describe conditions
>> more specific than the simple address size limit (i.e. bridge
>> windows), so even if both are present, the range inferred from _DMA
>> will always be less than or equal to that inferred from IORT, and
>> thus rather than explicitly calculating the intersection of the two
>> we can simply do this short-circuit.
>>
>> If IORT accurately reflects the total number of usable address bits,
>> then I can't see that it would ever make sense for _DMA to specify
>> an address range which exceeds that; I guess it comes down to how
>> much effort we want to spend verifying firmware instead of trusting
>> it.
> 
> I agree with this reasoning and the patch looks fine, I have not
> queued anything for this cycle for IORT so I would ask Will/Catalin
> to pick it up (if we still have time for v4.19):
> 
> Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>

Cheers Lorenzo (and Hanjun). Given that my DMA mask series[1] is 
nominally based on top of this, it might make sense for Christoph to 
pick it up through the dma-mapping tree. Since I'm about to send a new 
version of that series I'll resend this one as part of that.

Thanks,
Robin.

[1] 
https://www.mail-archive.com/iommu@lists.linux-foundation.org/msg24358.html

[PATCH] ACPI/IORT: Support address size limit for root complexes

[Robin Murphy]

[+Christoph]

On 18/07/18 17:36, Lorenzo Pieralisi wrote:
> [+Catalin, Will]
> 
> On Mon, Jul 16, 2018 at 04:34:51PM +0100, Robin Murphy wrote:
>> On 2018-07-16 4:10 PM, Lorenzo Pieralisi wrote:
>>> On Tue, Jul 10, 2018 at 05:13:45PM +0100, Robin Murphy wrote:
>>>> IORT revision D allows PCI root complex nodes to specify a memory
>>>> address size limit equivalently to named components, to help describe
>>>> straightforward integrations which don't really warrant a full-blown
>>>> _DMA method. Now that our headers are up-to-date, plumb it in.
>>>>
>>>> Signed-off-by: Robin Murphy <robin.murphy@arm.com>
>>>> ---
>>>>   drivers/acpi/arm64/iort.c | 25 +++++++++++++++++++++++--
>>>>   1 file changed, 23 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
>>>> index 7a3a541046ed..4a66896e2aa3 100644
>>>> --- a/drivers/acpi/arm64/iort.c
>>>> +++ b/drivers/acpi/arm64/iort.c
>>>> @@ -947,6 +947,24 @@ static int nc_dma_get_range(struct device *dev, u64 *size)
>>>>   	return 0;
>>>>   }
>>>> +static int rc_dma_get_range(struct device *dev, u64 *size)
>>>> +{
>>>> +	struct acpi_iort_node *node;
>>>> +	struct acpi_iort_root_complex *rc;
>>>> +
>>>> +	node = iort_scan_node(ACPI_IORT_NODE_PCI_ROOT_COMPLEX,
>>>> +			      iort_match_node_callback, dev);
>>>> +	if (!node || node->revision < 1)
>>>> +		return -ENODEV;
>>>> +
>>>> +	rc = (struct acpi_iort_root_complex *)node->node_data;
>>>> +
>>>> +	*size = rc->memory_address_limit >= 64 ? U64_MAX :
>>>> +			1ULL<<rc->memory_address_limit;
>>>> +
>>>> +	return 0;
>>>> +}
>>>> +
>>>>   /**
>>>>    * iort_dma_setup() - Set-up device DMA parameters.
>>>>    *
>>>> @@ -975,10 +993,13 @@ void iort_dma_setup(struct device *dev, u64 *dma_addr, u64 *dma_size)
>>>>   	size = max(dev->coherent_dma_mask, dev->coherent_dma_mask + 1);
>>>> -	if (dev_is_pci(dev))
>>>> +	if (dev_is_pci(dev)) {
>>>>   		ret = acpi_dma_get_range(dev, &dmaaddr, &offset, &size);
>>>> -	else
>>>> +		if (ret == -ENODEV)
>>>> +			ret = rc_dma_get_range(dev, &size);
>>>
>>> Thank you for putting together the patch.
>>>
>>> The question is whether it is OK to ignore the IORT address limits
>>> when _DMA is actually specified. It is a sort of grey area that
>>> has to be clarified, maybe we can add a check to detect a size
>>> mismatch, I do not know if something should be added at IORT spec
>>> level to clarify its relation to the _DMA object, if present.
>>
>> Yeah, I'm assuming that _DMA would be used to describe conditions
>> more specific than the simple address size limit (i.e. bridge
>> windows), so even if both are present, the range inferred from _DMA
>> will always be less than or equal to that inferred from IORT, and
>> thus rather than explicitly calculating the intersection of the two
>> we can simply do this short-circuit.
>>
>> If IORT accurately reflects the total number of usable address bits,
>> then I can't see that it would ever make sense for _DMA to specify
>> an address range which exceeds that; I guess it comes down to how
>> much effort we want to spend verifying firmware instead of trusting
>> it.
> 
> I agree with this reasoning and the patch looks fine, I have not
> queued anything for this cycle for IORT so I would ask Will/Catalin
> to pick it up (if we still have time for v4.19):
> 
> Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>

Cheers Lorenzo (and Hanjun). Given that my DMA mask series[1] is 
nominally based on top of this, it might make sense for Christoph to 
pick it up through the dma-mapping tree. Since I'm about to send a new 
version of that series I'll resend this one as part of that.

Thanks,
Robin.

[1] 
https://www.mail-archive.com/iommu at lists.linux-foundation.org/msg24358.html