Re: [PATCH] platform/x86: intel_pmc_core: Do not ioremap RAM

[Andy Shevchenko]

On Fri, Aug 16, 2019 at 4:42 AM M. Vefa Bicakci <m.v.b@xxxxxxxxxx> wrote:
>
> On a Xen-based PVH virtual machine with more than 4 GiB of RAM,
> intel_pmc_core fails initialization with the following warning message
> from the kernel, indicating that the driver is attempting to ioremap
> RAM:
>
>   ------------[ cut here ]------------
>   ioremap on RAM at 0x00000000fe000000 - 0x00000000fe001fff

> This issue appears to manifest itself because of the following fallback
> mechanism in the driver:
>
>         if (lpit_read_residency_count_address(&slp_s0_addr))
>                 pmcdev->base_addr = PMC_BASE_ADDR_DEFAULT;
>
> The validity of address PMC_BASE_ADDR_DEFAULT (i.e., 0xFE000000) is not
> verified by the driver, which is what this patch introduces. With this
> patch, if address PMC_BASE_ADDR_DEFAULT is in RAM, then the driver will
> not attempt to ioremap the aforementioned address.

Thank you for the patch.
Is there anything preventing us to use memremap() in such case?

-- 
With Best Regards,
Andy Shevchenko