diff options
Diffstat (limited to 'arch/x86/mm/pageattr.c')
| -rw-r--r-- | arch/x86/mm/pageattr.c | 27 |
1 files changed, 23 insertions, 4 deletions
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index 5160334f9095..bbc5eb5cbc9d 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -854,10 +854,28 @@ static int __should_split_large_page(pte_t *kpte, unsigned long address, } /* - * Make sure that the requested pgprot does not violate the static - * protections. Check the full large page whether one of the pages - * in it results in a different pgprot than the first one of the - * requested range. If yes, then the page needs to be split. + * Optimization: Check whether the requested pgprot is conflicting + * with a static protection requirement in the large page. If not, + * then checking whether the requested range is fully covering the + * large page can be done right here. + */ + new_prot = static_protections(req_prot, lpaddr, old_pfn, numpages, + CPA_DETECT); + + if (pgprot_val(req_prot) == pgprot_val(new_prot)) { + if (address != lpaddr || cpa->numpages != numpages) + return 1; + goto setlp; + } + + /* + * Slow path. The full large page check above established that the + * requested pgprot cannot be applied to the full large page due to + * conflicting requirements of static protection regions. It might + * turn out that the whole requested range is covered by the + * modified protection of the first 4k segment at @address. This + * might result in the ability to preserve the large page + * nevertheless. */ new_prot = static_protections(req_prot, address, pfn, 1, CPA_DETECT); pfn = old_pfn; @@ -882,6 +900,7 @@ static int __should_split_large_page(pte_t *kpte, unsigned long address, if (address != lpaddr || cpa->numpages != numpages) return 1; +setlp: /* All checks passed. Update the large page mapping. */ new_pte = pfn_pte(old_pfn, new_prot); __set_pmd_pte(kpte, address, new_pte); |