Re: [PATCH v4 09/12] x86/mtrr: construct a memory map with cache modes

[Juergen Gross]

On 31.03.23 14:57, Borislav Petkov wrote:
> On Mon, Mar 06, 2023 at 05:34:22PM +0100, Juergen Gross wrote:
> > +/* Build the cache_map containing the cache modes per memory range. */
> > +void mtrr_build_map(void)
> > +{
> > +	unsigned int i;
> > +	u64 start, end, size;
> > +	u8 type;
> > +
> > +	if (!mtrr_state.enabled)
> 	     ^^^^^^^^^^^^^^^^^^^
>
> > +		return;
> > +
> > +	/* Add fixed MTRRs, optimize for adjacent entries with same type. */
> > +	if (mtrr_state.enabled & MTRR_STATE_MTRR_FIXED_ENABLED) {
> 	    ^^^^^^^^^^^^^^^^^^
>
> First check can go.

Hmm, this makes it much harder to see that the code really does nothing
if enabled isn't set.

> > +		start = 0;
> > +		end = size = 0x10000;
> > +		type = mtrr_state.fixed_ranges[0];
> > +
> > +		for (i = 1; i < MTRR_NUM_FIXED_RANGES; i++) {
>
> Loops starts at 1. Comment explaining why pls.

Okay.

> > +			if (i == 8 || i == 24)
>
> Magic numbers.

I'll add more comments.

> Ok, I'll stop here.
>
> Please send a new version with the review comments incorporated. I need
> to look more at that map thing more.

Will do.


Thanks,

Juergen

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