From patchwork Sat May 30 10:59:18 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Xiao Guangrong X-Patchwork-Id: 6512681 Return-Path: X-Original-To: patchwork-kvm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id C9F619F402 for ; Sat, 30 May 2015 11:00:08 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id C8FA120850 for ; Sat, 30 May 2015 11:00:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C06ED20851 for ; Sat, 30 May 2015 11:00:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757831AbbE3K74 (ORCPT ); Sat, 30 May 2015 06:59:56 -0400 Received: from mga11.intel.com ([192.55.52.93]:40825 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757770AbbE3K7p (ORCPT ); Sat, 30 May 2015 06:59:45 -0400 Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga102.fm.intel.com with ESMTP; 30 May 2015 03:59:43 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.13,522,1427785200"; d="scan'208";a="717943243" Received: from slu40-mobl2.ccr.corp.intel.com (HELO homedesktop.ccr.corp.intel.com) ([10.254.212.183]) by fmsmga001.fm.intel.com with ESMTP; 30 May 2015 03:59:41 -0700 From: Xiao Guangrong To: pbonzini@redhat.com Cc: gleb@kernel.org, mtosatti@redhat.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Xiao Guangrong Subject: [PATCH 07/15] KVM: MTRR: improve kvm_mtrr_get_guest_memory_type Date: Sat, 30 May 2015 18:59:18 +0800 Message-Id: <1432983566-15773-8-git-send-email-guangrong.xiao@linux.intel.com> X-Mailer: git-send-email 2.1.0 In-Reply-To: <1432983566-15773-1-git-send-email-guangrong.xiao@linux.intel.com> References: <1432983566-15773-1-git-send-email-guangrong.xiao@linux.intel.com> Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP - kvm_mtrr_get_guest_memory_type() only checks one page in MTRRs so that it's unnecessary to check to see if the range is partially covered in MTRR - optimize the check of overlap memory type and add some comments to explain the precedence Signed-off-by: Xiao Guangrong --- arch/x86/kvm/mtrr.c | 89 ++++++++++++++++++++++++++--------------------------- 1 file changed, 44 insertions(+), 45 deletions(-) diff --git a/arch/x86/kvm/mtrr.c b/arch/x86/kvm/mtrr.c index bc9c6da..d3c06d2 100644 --- a/arch/x86/kvm/mtrr.c +++ b/arch/x86/kvm/mtrr.c @@ -231,24 +231,16 @@ int kvm_mtrr_get_msr(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata) return 0; } -/* - * The function is based on mtrr_type_lookup() in - * arch/x86/kernel/cpu/mtrr/generic.c - */ -static int get_mtrr_type(struct kvm_mtrr *mtrr_state, - u64 start, u64 end) +u8 kvm_mtrr_get_guest_memory_type(struct kvm_vcpu *vcpu, gfn_t gfn) { - u64 base, mask; - u8 prev_match, curr_match; - int i, num_var_ranges = KVM_NR_VAR_MTRR; + struct kvm_mtrr *mtrr_state = &vcpu->arch.mtrr_state; + u64 base, mask, start = gfn_to_gpa(gfn); + int i, num_var_ranges = KVM_NR_VAR_MTRR, type_mask, type = -1; /* MTRR is completely disabled, use UC for all of physical memory. */ if (!mtrr_state->mtrr_enabled) return MTRR_TYPE_UNCACHABLE; - /* Make end inclusive end, instead of exclusive */ - end--; - /* Look in fixed ranges. Just return the type as per start */ if (mtrr_state->fixed_mtrr_enabled && (start < 0x100000)) { int idx; @@ -273,9 +265,9 @@ static int get_mtrr_type(struct kvm_mtrr *mtrr_state, * Look of multiple ranges matching this address and pick type * as per MTRR precedence */ - prev_match = 0xFF; + type_mask = (1 << MTRR_TYPE_WRBACK) | (1 << MTRR_TYPE_WRTHROUGH); for (i = 0; i < num_var_ranges; ++i) { - unsigned short start_state, end_state; + int curr_type; if (!(mtrr_state->var_ranges[i].mask & (1 << 11))) continue; @@ -283,50 +275,57 @@ static int get_mtrr_type(struct kvm_mtrr *mtrr_state, base = mtrr_state->var_ranges[i].base & PAGE_MASK; mask = mtrr_state->var_ranges[i].mask & PAGE_MASK; - start_state = ((start & mask) == (base & mask)); - end_state = ((end & mask) == (base & mask)); - if (start_state != end_state) - return 0xFE; - if ((start & mask) != (base & mask)) continue; - curr_match = mtrr_state->var_ranges[i].base & 0xff; - if (prev_match == 0xFF) { - prev_match = curr_match; + /* + * Please refer to Intel SDM Volume 3: 11.11.4.1 MTRR + * Precedences. + */ + + curr_type = mtrr_state->var_ranges[i].base & 0xff; + if (type == -1) { + type = curr_type; continue; } - if (prev_match == MTRR_TYPE_UNCACHABLE || - curr_match == MTRR_TYPE_UNCACHABLE) + /* + * If two or more variable memory ranges match and the + * memory types are identical, then that memory type is + * used. + */ + if (type == curr_type) + continue; + + /* + * If two or more variable memory ranges match and one of + * the memory types is UC, the UC memory type used. + */ + if (curr_type == MTRR_TYPE_UNCACHABLE) return MTRR_TYPE_UNCACHABLE; - if ((prev_match == MTRR_TYPE_WRBACK && - curr_match == MTRR_TYPE_WRTHROUGH) || - (prev_match == MTRR_TYPE_WRTHROUGH && - curr_match == MTRR_TYPE_WRBACK)) { - prev_match = MTRR_TYPE_WRTHROUGH; - curr_match = MTRR_TYPE_WRTHROUGH; + /* + * If two or more variable memory ranges match and the + * memory types are WT and WB, the WT memory type is used. + */ + if (((1 << type) & type_mask) && + ((1 << curr_type) & type_mask)) { + type = MTRR_TYPE_WRTHROUGH; + continue; } - if (prev_match != curr_match) - return MTRR_TYPE_UNCACHABLE; + /* + * For overlaps not defined by the above rules, processor + * behavior is undefined. + */ + + /* We use WB for this undefined behavior. :( */ + return MTRR_TYPE_WRBACK; } - if (prev_match != 0xFF) - return prev_match; + if (type != -1) + return type; return mtrr_state->def_type; } - -u8 kvm_mtrr_get_guest_memory_type(struct kvm_vcpu *vcpu, gfn_t gfn) -{ - u8 mtrr; - - mtrr = get_mtrr_type(&vcpu->arch.mtrr_state, gfn << PAGE_SHIFT, - (gfn << PAGE_SHIFT) + PAGE_SIZE); - if (mtrr == 0xfe || mtrr == 0xff) - mtrr = MTRR_TYPE_WRBACK; - return mtrr; -} EXPORT_SYMBOL_GPL(kvm_mtrr_get_guest_memory_type);