From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753514AbbCJUYn (ORCPT ); Tue, 10 Mar 2015 16:24:43 -0400 Received: from g1t5424.austin.hp.com ([15.216.225.54]:44591 "EHLO g1t5424.austin.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751942AbbCJUYK (ORCPT ); Tue, 10 Mar 2015 16:24:10 -0400 From: Toshi Kani To: akpm@linux-foundation.org, hpa@zytor.com, tglx@linutronix.de, mingo@redhat.com, arnd@arndb.de Cc: linux-mm@kvack.org, x86@kernel.org, linux-kernel@vger.kernel.org, dave.hansen@intel.com, Elliott@hp.com, pebolle@tiscali.nl, Toshi Kani Subject: [PATCH 2/3] mtrr, x86: Fix MTRR lookup to handle inclusive entry Date: Tue, 10 Mar 2015 14:23:16 -0600 Message-Id: <1426018997-12936-3-git-send-email-toshi.kani@hp.com> X-Mailer: git-send-email 1.9.3 In-Reply-To: <1426018997-12936-1-git-send-email-toshi.kani@hp.com> References: <1426018997-12936-1-git-send-email-toshi.kani@hp.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When an MTRR entry is inclusive to a requested range, i.e. the start and end of the request are not within the MTRR entry range but the range contains the MTRR entry entirely, __mtrr_type_lookup() ignores such case because both start_state and end_state are set to zero. This patch fixes the issue by adding a new flag, inclusive, to detect the case. This case is then handled in the same way as (!start_state && end_state). Also updated the comment in __mtrr_type_lookup() to clarify that the repeat handling is necessary to handle overlaps with the default type, since overlaps with multiple entries alone can be handled without such repeat. Signed-off-by: Toshi Kani --- arch/x86/kernel/cpu/mtrr/generic.c | 20 +++++++++++--------- 1 file changed, 11 insertions(+), 9 deletions(-) diff --git a/arch/x86/kernel/cpu/mtrr/generic.c b/arch/x86/kernel/cpu/mtrr/generic.c index 7d74f7b..cdb955f 100644 --- a/arch/x86/kernel/cpu/mtrr/generic.c +++ b/arch/x86/kernel/cpu/mtrr/generic.c @@ -154,7 +154,7 @@ static u8 __mtrr_type_lookup(u64 start, u64 end, u64 *partial_end, int *repeat) prev_match = 0xFF; for (i = 0; i < num_var_ranges; ++i) { - unsigned short start_state, end_state; + unsigned short start_state, end_state, inclusive; if (!(mtrr_state.var_ranges[i].mask_lo & (1 << 11))) continue; @@ -166,20 +166,22 @@ static u8 __mtrr_type_lookup(u64 start, u64 end, u64 *partial_end, int *repeat) start_state = ((start & mask) == (base & mask)); end_state = ((end & mask) == (base & mask)); + inclusive = ((start < base) && (end > base)); - if (start_state != end_state) { + if ((start_state != end_state) || inclusive) { /* * We have start:end spanning across an MTRR. - * We split the region into - * either - * (start:mtrr_end) (mtrr_end:end) - * or - * (start:mtrr_start) (mtrr_start:end) + * We split the region into either + * - start_state:1 + * (start:mtrr_end) (mtrr_end:end) + * - end_state:1 or inclusive:1 + * (start:mtrr_start) (mtrr_start:end) * depending on kind of overlap. * Return the type for first region and a pointer to * the start of second region so that caller will * lookup again on the second region. - * Note: This way we handle multiple overlaps as well. + * Note: This way we handle overlaps with multiple + * entries and the default type properly. */ if (start_state) *partial_end = base + get_mtrr_size(mask); @@ -195,7 +197,7 @@ static u8 __mtrr_type_lookup(u64 start, u64 end, u64 *partial_end, int *repeat) *repeat = 1; } - if ((start & mask) != (base & mask)) + if (!start_state) continue; curr_match = mtrr_state.var_ranges[i].base_lo & 0xff;