On Mon, Sep 17, 2018 at 04:29:14PM +0200, Thomas Gleixner wrote:
> +static void split_set_pte(struct cpa_data *cpa, pte_t *pte, unsigned long
> pfn,
> + pgprot_t ref_prot, unsigned long address,
> + unsigned long size)
> +{
> + unsigned int npg = PFN_DOWN(size);
> + pgprot_t prot;
> +
> + /*
> + * If try_preserve_large_page() discovered an inconsistent mapping,
You just renamed that thing.. :-)
> + * remove the invalid protection in the split mapping.
> + */
> + if (!cpa->force_static_prot)
> + goto set;
> +
> + prot = static_protections(ref_prot, address, pfn, npg, CPA_PROTECT);
> +
> + if (pgprot_val(prot) == pgprot_val(ref_prot))
> + goto set;
> +
> + /*
> + * If this is splitting a PMD, fix it up. PUD splits cannot be
> + * fixed trivially as that would require to rescan the newly
> + * installed PMD mappings after returning from split_large_page()
> + * so an eventual further split can allocate the necessary PTE
> + * pages. Warn for now and revisit it in case this actually
> + * happens.
> + */
> + if (size == PAGE_SIZE)
> + ref_prot = prot;
> + else
> + pr_warn_once("CPA: Cannot fixup static protections for PUD
> split\n");
> +set:
> + set_pte(pte, pfn_pte(pfn, ref_prot));
> +}
