RE: [PATCH 02/15] cxl/core: Check physical address before mapping it in devm_cxl_iomap_block()

From: Dan Williams
Date: Thu Sep 08 2022 - 01:49:14 EST


Robert Richter 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().
>
> Signed-off-by: Robert Richter <rrichter@xxxxxxx>
> ---
> 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;
> --
> 2.30.2
>

devm_request_mem_region() succeeds for you when this happens? More
details about the failure scenario please.