[PATCH 0/1] cxl/pmem: debug invalid serial number data

[PATCH 0/1] cxl/pmem: debug invalid serial number data

[Yuquan Wang]

Background
==========
In Qemu environment, the default serial number of cxl-type3 device
is UI64_NULL. But we could still use it to create a nvdimm pmem region
and set a non-zero cookie of nd_interleave_set, for example:
  1. create a cxl pmem region interleaved with 2 devices (one with
     serial number 0 and the other with serial number 1), and the cookie
     would be non-zero/valid.
  2. create the second cxl pmem region by 1 device with no serial number
     and this region would have a non-zero cookie because the offset of
     dpa is non-zero.

Problem
=======
In a nvdimm interleave-set each device with an invalid or zero
serial number may cause pmem region initialization to fail, but in
cxl case such device could still set cookies of nd_interleave_set
and create a nvdimm pmem region.

CXL Pmem Validation
===================
This patch adds the validation of serial number in cxl pmem region creation.
The event of no serial number would cause to fail to set the cookie
and pmem region.

Yuquan Wang (1):
  cxl/pmem: debug invalid serial number data

 drivers/cxl/pmem.c | 7 +++++++
 1 file changed, 7 insertions(+)

-- 
2.34.1

[PATCH 1/1] cxl/pmem: debug invalid serial number data

[Yuquan Wang]

In a nvdimm interleave-set each device with an invalid or zero
serial number may cause pmem region initialization to fail, but in
cxl case such device could still set cookies of nd_interleave_set
and create a nvdimm pmem region.

This adds the validation of serial number in cxl pmem region creation.
The event of no serial number would cause to fail to set the cookie
and pmem region.

Signed-off-by: Yuquan Wang <wangyuquan1236@phytium.com.cn>
---
 drivers/cxl/pmem.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/cxl/pmem.c b/drivers/cxl/pmem.c
index f9c95996e937..89f4eac49313 100644
--- a/drivers/cxl/pmem.c
+++ b/drivers/cxl/pmem.c
@@ -384,6 +384,13 @@ static int cxl_pmem_region_probe(struct device *dev)
 		};
 		info[i].offset = m->start;
 		info[i].serial = cxlds->serial;
+
+		if (info[i].serial == 0) {
+			dev_dbg(dev, "%s: invalid serial number\n",
+				dev_name(&cxlmd->dev));
+			rc = -ENXIO;
+			goto out_nvd;
+		}
 	}
 	ndr_desc.num_mappings = cxlr_pmem->nr_mappings;
 	ndr_desc.mapping = mappings;
-- 
2.34.1

Re: [PATCH 1/1] cxl/pmem: debug invalid serial number data

[Alison Schofield]

On Thu, Feb 13, 2025 at 02:40:08PM +0800, Yuquan Wang wrote:
> In a nvdimm interleave-set each device with an invalid or zero
> serial number may cause pmem region initialization to fail, but in
> cxl case such device could still set cookies of nd_interleave_set
> and create a nvdimm pmem region.
> 
> This adds the validation of serial number in cxl pmem region creation.
> The event of no serial number would cause to fail to set the cookie
> and pmem region.

This trips up cxl-test where a mock serial number is set from the
platform device id and 0 is a valid platform device id.

Take a look at doing this cxl_mock_mem_probe():
-       cxlds->serial = pdev->id;
+       cxlds->serial = pdev->id + 1;

--snip

Re: [PATCH 1/1] cxl/pmem: debug invalid serial number data

[Fan Ni]

On Thu, Feb 13, 2025 at 02:40:08PM +0800, Yuquan Wang wrote:
> In a nvdimm interleave-set each device with an invalid or zero
> serial number may cause pmem region initialization to fail, but in
> cxl case such device could still set cookies of nd_interleave_set
> and create a nvdimm pmem region.
> 
> This adds the validation of serial number in cxl pmem region creation.
> The event of no serial number would cause to fail to set the cookie
> and pmem region.
> 
> Signed-off-by: Yuquan Wang <wangyuquan1236@phytium.com.cn>
> ---
>  drivers/cxl/pmem.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/cxl/pmem.c b/drivers/cxl/pmem.c
> index f9c95996e937..89f4eac49313 100644
> --- a/drivers/cxl/pmem.c
> +++ b/drivers/cxl/pmem.c
> @@ -384,6 +384,13 @@ static int cxl_pmem_region_probe(struct device *dev)
>  		};
>  		info[i].offset = m->start;
>  		info[i].serial = cxlds->serial;
> +
> +		if (info[i].serial == 0) {
> +			dev_dbg(dev, "%s: invalid serial number\n",

Should we use dev_err() instead? 

Fan
> +				dev_name(&cxlmd->dev));
> +			rc = -ENXIO;
> +			goto out_nvd;
> +		}
>  	}
>  	ndr_desc.num_mappings = cxlr_pmem->nr_mappings;
>  	ndr_desc.mapping = mappings;
> -- 
> 2.34.1
>