On 06/13/2013 11:53 AM, Yinghai Lu wrote:
>
> - if (base & size_or_mask || size & size_or_mask) {
> + if (base >> (boot_cpu_data.x86_phys_bits - PAGE_SHIFT) ||
> + base > (base + size) ||
> + (base + size - 1) >> (boot_cpu_data.x86_phys_bits - PAGE_SHIFT)) {
> pr_warning("mtrr: base or size exceeds the MTRR width\n");
> return -EINVAL;
> }
Most of this patch looks good as far as being a minimal patch, but I'm
really confused about this bit. Could you explain the reason for why
the original doesn't work? (To be fair: I am not even sure the original
does anything useful so it could just be a "this is just too broken to
live" kind of thing.)
The first and third clause of the test can be simplified, however:
(base | (base + size - 1)) >> (boot_cpu_data.x86_phys_bits - PAGE_SHIFT)
... although it would be cleaner to put boot_cpu_data.x86_phys_bits -
PAGE_SHIFT into a variable.
A lot of the mask_hi/mask_lo stuff should just get removed by using
rdmsrl/wrmsrl, but that is not stable material obviously.
-hpa
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