From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751630AbeBVUi2 (ORCPT ); Thu, 22 Feb 2018 15:38:28 -0500 Received: from mga12.intel.com ([192.55.52.136]:15124 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751437AbeBVUhJ (ORCPT ); Thu, 22 Feb 2018 15:37:09 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.47,378,1515484800"; d="scan'208";a="20353992" Subject: [RFC][PATCH 06/10] x86/mm: remove extra filtering in pageattr code To: linux-kernel@vger.kernel.org Cc: Dave Hansen , aarcange@redhat.com, luto@kernel.org, torvalds@linux-foundation.org, keescook@google.com, hughd@google.com, jgross@suse.com, x86@kernel.org, namit@vmware.com From: Dave Hansen Date: Thu, 22 Feb 2018 12:37:01 -0800 References: <20180222203651.B776810C@viggo.jf.intel.com> In-Reply-To: <20180222203651.B776810C@viggo.jf.intel.com> Message-Id: <20180222203701.0518257D@viggo.jf.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Dave Hansen The pageattr code has a mode where it can set or clear PTE bits in existing PTEs, so the page protections of the *new* PTEs come from one of two places: 1. The set/clear masks: cpa->mask_clr / cpa->mask_set 2. The existing PTE We filter ->mask_set/clr for supported PTE bits at entry to __change_page_attr() so we never need to filter them again. The only other place permissions can come from is an existing PTE and those already presumably have good bits. We do not need to filter them again. Signed-off-by: Dave Hansen Cc: Andrea Arcangeli Cc: Andy Lutomirski Cc: Linus Torvalds Cc: Kees Cook Cc: Hugh Dickins Cc: Juergen Gross Cc: x86@kernel.org Cc: Nadav Amit --- b/arch/x86/mm/pageattr.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff -puN arch/x86/mm/pageattr.c~x86-pageattr-dont-filter-global arch/x86/mm/pageattr.c --- a/arch/x86/mm/pageattr.c~x86-pageattr-dont-filter-global 2018-02-22 12:36:20.456036549 -0800 +++ b/arch/x86/mm/pageattr.c 2018-02-22 12:36:20.460036549 -0800 @@ -598,7 +598,6 @@ try_preserve_large_page(pte_t *kpte, uns req_prot = pgprot_clear_protnone_bits(req_prot); if (pgprot_val(req_prot) & _PAGE_PRESENT) pgprot_val(req_prot) |= _PAGE_PSE; - req_prot = canon_pgprot(req_prot); /* * old_pfn points to the large page base pfn. So we need @@ -718,7 +717,7 @@ __split_large_page(struct cpa_data *cpa, */ pfn = ref_pfn; for (i = 0; i < PTRS_PER_PTE; i++, pfn += pfninc) - set_pte(&pbase[i], pfn_pte(pfn, canon_pgprot(ref_prot))); + set_pte(&pbase[i], pfn_pte(pfn, ref_prot)); if (virt_addr_valid(address)) { unsigned long pfn = PFN_DOWN(__pa(address)); @@ -935,7 +934,6 @@ static void populate_pte(struct cpa_data pte = pte_offset_kernel(pmd, start); pgprot = pgprot_clear_protnone_bits(pgprot); - pgprot = canon_pgprot(pgprot); while (num_pages-- && start < end) { set_pte(pte, pfn_pte(cpa->pfn, pgprot)); @@ -1234,7 +1232,7 @@ repeat: * after all we're only going to change it's attributes * not the memory it points to */ - new_pte = pfn_pte(pfn, canon_pgprot(new_prot)); + new_pte = pfn_pte(pfn, new_prot); cpa->pfn = pfn; /* * Do we really change anything ? _