Re: [PATCH 2/4] KVM: Avoid checking huge page mappings inget_dirty_log()

[Takuya Yoshikawa]

Takuya Yoshikawa <yoshikawa.takuya@xxxxxxxxxxxxx> wrote:

> +	while (mask) {
> +		rmapp = &slot->rmap[gfn_offset + __ffs(mask)];
> +		__rmap_write_protect(kvm, rmapp, PT_PAGE_TABLE_LEVEL);
>  
> -	return write_protected;
> +		/* clear the first set bit */
> +		mask &= mask - 1;
> +	}
>  }

while (mask) {
	fsbit = __ffs(mask);
	gfn_offset += fsbit;
	mask >>= fsbit + 1;

	rmapp = &slot->rmap[gfn_offset];
	__rmap_write_protect(kvm, rmapp, PT_PAGE_TABLE_LEVEL);
}

Seems to be better: BSF friendly.

I will update this function and post the result with dirty-log-perf output!

	Takuya
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