Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751743AbbEFVnD (ORCPT ); Wed, 6 May 2015 17:43:03 -0400 Received: from mail-ig0-f177.google.com ([209.85.213.177]:38005 "EHLO mail-ig0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751282AbbEFVnA (ORCPT ); Wed, 6 May 2015 17:43:00 -0400 MIME-Version: 1.0 In-Reply-To: <1430389490-24602-12-git-send-email-guangrong.xiao@linux.intel.com> References: <1430389490-24602-1-git-send-email-guangrong.xiao@linux.intel.com> <1430389490-24602-12-git-send-email-guangrong.xiao@linux.intel.com> From: David Matlack Date: Wed, 6 May 2015 14:42:39 -0700 Message-ID: Subject: Re: [PATCH 1/9] KVM: MMU: fix decoding cache type from MTRR To: guangrong.xiao@linux.intel.com Cc: Paolo Bonzini , Gleb Natapov , Marcelo Tosatti , kvm list , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3054 Lines: 82 On Thu, Apr 30, 2015 at 3:24 AM, wrote: > From: Xiao Guangrong > > There are some bugs in current get_mtrr_type(); > 1: bit 2 of mtrr_state->enabled is corresponding bit 11 of IA32_MTRR_DEF_TYPE bit 1, not bit 2. (code is correct though) > MSR which completely control MTRR's enablement that means other bits are > ignored if it is cleared > > 2: the fixed MTRR ranges are controlled by bit 1 of mtrr_state->enabled (bit 10 bit 0, not bit 1. (code is correct though) > of IA32_MTRR_DEF_TYPE) > > 3: if MTRR is disabled, UC is applied to all of physical memory rather than > mtrr_state->def_type kvm_get_guest_memory_type defaults to MTRR_TYPE_WRBACK, not mtrr_state->def_type, when get_mtrr_type returns 0xFF. > > Signed-off-by: Xiao Guangrong > --- > arch/x86/kvm/mmu.c | 14 ++++++-------- > 1 file changed, 6 insertions(+), 8 deletions(-) > > diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c > index d43867c..ea3e3e4 100644 > --- a/arch/x86/kvm/mmu.c > +++ b/arch/x86/kvm/mmu.c > @@ -2393,19 +2393,20 @@ EXPORT_SYMBOL_GPL(kvm_mmu_unprotect_page); > static int get_mtrr_type(struct mtrr_state_type *mtrr_state, > u64 start, u64 end) > { > - int i; > u64 base, mask; > u8 prev_match, curr_match; > - int num_var_ranges = KVM_NR_VAR_MTRR; > + int i, num_var_ranges = KVM_NR_VAR_MTRR; > > - if (!mtrr_state->enabled) > - return 0xFF; > + /* MTRR is completely disabled, use UC for all of physical memory. */ > + if (!(mtrr_state->enabled & 0x2)) > + 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->have_fixed && (start < 0x100000)) { > + if (mtrr_state->have_fixed && (mtrr_state->enabled & 0x1) && > + (start < 0x100000)) { > int idx; > > if (start < 0x80000) { > @@ -2428,9 +2429,6 @@ static int get_mtrr_type(struct mtrr_state_type *mtrr_state, > * Look of multiple ranges matching this address and pick type > * as per MTRR precedence > */ > - if (!(mtrr_state->enabled & 2)) > - return mtrr_state->def_type; > - > prev_match = 0xFF; > for (i = 0; i < num_var_ranges; ++i) { > unsigned short start_state, end_state; > -- > 1.9.3 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/