Hi,
On Tue, Oct 15, 2019 at 09:49:32AM -0700, Yian Chen wrote:
> VT-d RMRR (Reserved Memory Region Reporting) regions are reserved
> for device use only and should not be part of allocable memory pool of OS.
>
> BIOS e820_table reports complete memory map to OS, including OS usable
> memory ranges and BIOS reserved memory ranges etc.
>
> x86 BIOS may not be trusted to include RMRR regions as reserved type
> of memory in its e820 memory map, hence validate every RMRR entry
> with the e820 memory map to make sure the RMRR regions will not be
> used by OS for any other purposes.
Are there real systems in the wild where this is a problem?
> +static inline int __init
> +arch_rmrr_sanity_check(struct acpi_dmar_reserved_memory *rmrr)
> +{
> + u64 start = rmrr->base_address;
> + u64 end = rmrr->end_address + 1;
> +
> + if (e820__mapped_all(start, end, E820_TYPE_RESERVED))
> + return 0;
> +
> + pr_err(FW_BUG "No firmware reserved region can cover this RMRR [%#018Lx-%#018Lx], contact BIOS vendor for fixes\n",
> + start, end - 1);
> + return -EFAULT;
> +}
Why -EFAULT, there is no fault involved? Usibg -EINVAL seems to be a better choice.
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