Re: [PATCH 4/4] cxl: Adjust offset calculation for poison injection

[Dave Jiang <dave.jiang@intel.com>]

On 10/31/25 1:58 PM, Alison Schofield wrote:
> On Fri, Oct 31, 2025 at 10:32:24AM -0700, Dave Jiang wrote:
>> The HPA to DPA translation for poison injection assumes that the
>> base address starts from where the CXL region begins. When the
>> extended linear cache is active, the offset can be within the DRAM
>> region. Adjust the offset so that it correctly reflects the offset
>> within the CXL region.
> 
> Dave, good catch!
> 
> This breakage was added in 6.18-rc1. Please consider it for a pull
> request before the end of 6.18.
> 
> Here's justification and Fixes Tag:
> 
> Without this patch, when a user intends to inject poison at an offset
> in region, it can inject poison into a location in a device that is
> not mapped by that region.
> 
> The test case in cxl-poison-elc.sh that exposed this issue, injected
> poison 0x20000000 which should have been the first byte of the CXL
> half of an Extended Linear Cache (ELC) region. Instead, it injected
> poison at the next byte of a device beyond the regions mapping.
> 
> Fixes: c3dd67681c70 ("cxl/region: Add inject and clear poison by region offset")
> 
> Reviewed-by: Alison Schofield <alison.schofield@intel.com>
> 
Yeah I can move it to fixes instead