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SubjectRe: [PATCH 02/15] cxl/core: Check physical address before mapping it in devm_cxl_iomap_block()
On Wed, 31 Aug 2022 10:15:50 +0200
Robert Richter <rrichter@amd.com> wrote:

> The physical base address of a CXL range can be invalid and is then
> set to CXL_RESOURCE_NONE. Early check this case before mapping a
> memory block in devm_cxl_iomap_block().

An example of when it is invalid would be a useful addition
to this description. Feels to me like this is papering over the cracks
in something we should have ruled out earlier in the flow.

Jonathan

>
> Signed-off-by: Robert Richter <rrichter@amd.com>
> ---
> drivers/cxl/core/regs.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/cxl/core/regs.c b/drivers/cxl/core/regs.c
> index 39a129c57d40..f216c017a474 100644
> --- a/drivers/cxl/core/regs.c
> +++ b/drivers/cxl/core/regs.c
> @@ -165,6 +165,9 @@ void __iomem *devm_cxl_iomap_block(struct device *dev, resource_size_t addr,
> void __iomem *ret_val;
> struct resource *res;
>
> + if (addr == CXL_RESOURCE_NONE)
> + return NULL;
> +
> res = devm_request_mem_region(dev, addr, length, dev_name(dev));
> if (!res) {
> resource_size_t end = addr + length - 1;

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