cxl: Address translation support, part 2: Generic support and AMD Zen5 platform enablement

[PATCH v2 08/15] cxl/region: Use the endpoint's SPA range to find a region

Posted by Robert Richter 10 months ago

To find the correct region and root port of an endpoint of a system
needing address translation, the endpoint's HPA range must be
translated to each of the parent port address ranges up to the root
decoder.

Use the calculated SPA range of an endpoint to find the endpoint's
region.

Signed-off-by: Robert Richter <rrichter@amd.com>
---
 drivers/cxl/core/region.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index 6d5ede5b4c43..ffe6038249ed 100644
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -3535,7 +3535,6 @@ static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
 
 static int cxl_endpoint_decoder_add(struct cxl_endpoint_decoder *cxled)
 {
-	struct range *hpa = &cxled->cxld.hpa_range;
 	struct cxl_root_decoder *cxlrd = cxled->cxlrd;
 	struct cxl_region_params *p;
 	struct cxl_region *cxlr;
@@ -3547,7 +3546,7 @@ static int cxl_endpoint_decoder_add(struct cxl_endpoint_decoder *cxled)
 	 * one does the construction and the others add to that.
 	 */
 	mutex_lock(&cxlrd->range_lock);
-	cxlr = cxl_find_region_by_range(cxlrd, hpa);
+	cxlr = cxl_find_region_by_range(cxlrd, &cxled->spa_range);
 	if (!cxlr)
 		cxlr = construct_region(cxlrd, cxled);
 	mutex_unlock(&cxlrd->range_lock);
-- 
2.39.5

Re: [PATCH v2 08/15] cxl/region: Use the endpoint's SPA range to find a region

Posted by Gregory Price 8 months, 2 weeks ago

On Tue, Feb 18, 2025 at 02:23:49PM +0100, Robert Richter wrote:
> To find the correct region and root port of an endpoint of a system
> needing address translation, the endpoint's HPA range must be
> translated to each of the parent port address ranges up to the root
> decoder.
> 
> Use the calculated SPA range of an endpoint to find the endpoint's
> region.
> 

After debugging some other patches, I think this patch needs to just be
rolled in with the introduction of cxled->spa_range (Patch 5).

(spa_range == hpa_range) up to this point, so this is effectively a NOP.

> Signed-off-by: Robert Richter <rrichter@amd.com>
> ---
>  drivers/cxl/core/region.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
> index 6d5ede5b4c43..ffe6038249ed 100644
> --- a/drivers/cxl/core/region.c
> +++ b/drivers/cxl/core/region.c
> @@ -3535,7 +3535,6 @@ static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
>  
>  static int cxl_endpoint_decoder_add(struct cxl_endpoint_decoder *cxled)
>  {
> -	struct range *hpa = &cxled->cxld.hpa_range;
>  	struct cxl_root_decoder *cxlrd = cxled->cxlrd;
>  	struct cxl_region_params *p;
>  	struct cxl_region *cxlr;
> @@ -3547,7 +3546,7 @@ static int cxl_endpoint_decoder_add(struct cxl_endpoint_decoder *cxled)
>  	 * one does the construction and the others add to that.
>  	 */
>  	mutex_lock(&cxlrd->range_lock);
> -	cxlr = cxl_find_region_by_range(cxlrd, hpa);
> +	cxlr = cxl_find_region_by_range(cxlrd, &cxled->spa_range);
>  	if (!cxlr)
>  		cxlr = construct_region(cxlrd, cxled);
>  	mutex_unlock(&cxlrd->range_lock);
> -- 
> 2.39.5
>

Re: [PATCH v2 08/15] cxl/region: Use the endpoint's SPA range to find a region

Posted by Jonathan Cameron 9 months, 1 week ago

On Tue, 18 Feb 2025 14:23:49 +0100
Robert Richter <rrichter@amd.com> wrote:

> To find the correct region and root port of an endpoint of a system
> needing address translation, the endpoint's HPA range must be
> translated to each of the parent port address ranges up to the root
> decoder.
> 
> Use the calculated SPA range of an endpoint to find the endpoint's
> region.
> 
> Signed-off-by: Robert Richter <rrichter@amd.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Re: [PATCH v2 08/15] cxl/region: Use the endpoint's SPA range to find a region

Posted by Gregory Price 10 months ago

On Tue, Feb 18, 2025 at 02:23:49PM +0100, Robert Richter wrote:
> To find the correct region and root port of an endpoint of a system
> needing address translation, the endpoint's HPA range must be
> translated to each of the parent port address ranges up to the root
> decoder.
> 
> Use the calculated SPA range of an endpoint to find the endpoint's
> region.
>
> Signed-off-by: Robert Richter <rrichter@amd.com>

May be worth noting that cxl_endpoint_initialize() will set
cxled->spa_range regardless of whether HPA=SPA or not, and so it will
always contain the correct value at this point - even if translation
was not required.

Reviewed-by: Gregory Price <gourry@gourry.net>

> ---
>  drivers/cxl/core/region.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
> index 6d5ede5b4c43..ffe6038249ed 100644
> --- a/drivers/cxl/core/region.c
> +++ b/drivers/cxl/core/region.c
> @@ -3535,7 +3535,6 @@ static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
>  
>  static int cxl_endpoint_decoder_add(struct cxl_endpoint_decoder *cxled)
>  {
> -	struct range *hpa = &cxled->cxld.hpa_range;
>  	struct cxl_root_decoder *cxlrd = cxled->cxlrd;
>  	struct cxl_region_params *p;
>  	struct cxl_region *cxlr;
> @@ -3547,7 +3546,7 @@ static int cxl_endpoint_decoder_add(struct cxl_endpoint_decoder *cxled)
>  	 * one does the construction and the others add to that.
>  	 */
>  	mutex_lock(&cxlrd->range_lock);
> -	cxlr = cxl_find_region_by_range(cxlrd, hpa);
> +	cxlr = cxl_find_region_by_range(cxlrd, &cxled->spa_range);
>  	if (!cxlr)
>  		cxlr = construct_region(cxlrd, cxled);
>  	mutex_unlock(&cxlrd->range_lock);
> -- 
> 2.39.5
>