From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754192AbaH2QsC (ORCPT ); Fri, 29 Aug 2014 12:48:02 -0400 Received: from mail-qc0-f178.google.com ([209.85.216.178]:61366 "EHLO mail-qc0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753894AbaH2QsA (ORCPT ); Fri, 29 Aug 2014 12:48:00 -0400 Message-ID: <5400AEBA.2080405@redhat.com> Date: Fri, 29 Aug 2014 18:47:54 +0200 From: Paolo Bonzini User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.0 MIME-Version: 1.0 To: Wanpeng Li CC: Marcelo Tosatti , Gleb Natapov , Zhang Yang , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Jan Kiszka Subject: Re: [PATCH v2 3/3] KVM: x86: #GP when attempts to write reserved bits of Variable Range MTRRs References: <1408439080-57721-1-git-send-email-wanpeng.li@linux.intel.com> <1408439080-57721-3-git-send-email-wanpeng.li@linux.intel.com> In-Reply-To: <1408439080-57721-3-git-send-email-wanpeng.li@linux.intel.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Il 19/08/2014 11:04, Wanpeng Li ha scritto: > Section 11.11.2.3 of the SDM mentions "All other bits in the IA32_MTRR_PHYSBASEn > and IA32_MTRR_PHYSMASKn registers are reserved; the processor generates a > general-protection exception(#GP) if software attempts to write to them". This > patch do it in kvm. > > Signed-off-by: Wanpeng Li This breaks if the guest maxphyaddr is higher than the host's (which sometimes happens depending on your hardware and how QEMU is configured). You need to use cpuid_maxphyaddr, like this diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index a375dfc42f6a..916e89515210 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1726,7 +1726,7 @@ static bool valid_mtrr_type(unsigned t) static bool mtrr_valid(struct kvm_vcpu *vcpu, u32 msr, u64 data) { int i; - u64 mask = 0; + u64 mask; if (!msr_mtrr_valid(msr)) return false; @@ -1750,8 +1750,7 @@ static bool mtrr_valid(struct kvm_vcpu *vcpu, u32 msr, u64 data) /* variable MTRRs */ WARN_ON(!(msr >= 0x200 && msr < 0x200 + 2 * KVM_NR_VAR_MTRR)); - for (i = 63; i > boot_cpu_data.x86_phys_bits; i--) - mask |= (1ULL << i); + mask = (~0ULL) << cpuid_maxphyaddr(vcpu); if ((msr & 1) == 0) { /* MTRR base */ if (!valid_mtrr_type(data & 0xff)) Jan, can you see if this patch fixes the SeaBIOS triple fault you reported? Paolo > --- > arch/x86/kvm/x86.c | 18 +++++++++++++++--- > 1 file changed, 15 insertions(+), 3 deletions(-) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index fb3ea7a..b85da5f 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -1726,6 +1726,7 @@ static bool valid_mtrr_type(unsigned t) > static bool mtrr_valid(struct kvm_vcpu *vcpu, u32 msr, u64 data) > { > int i; > + u64 mask = 0; > > if (!msr_mtrr_valid(msr)) > return false; > @@ -1749,10 +1750,21 @@ static bool mtrr_valid(struct kvm_vcpu *vcpu, u32 msr, u64 data) > /* variable MTRRs */ > WARN_ON(!(msr >= 0x200 && msr < 0x200 + 2 * KVM_NR_VAR_MTRR)); > > - if ((msr & 1) == 0) > + for (i = 63; i > boot_cpu_data.x86_phys_bits; i--) > + mask |= (1ULL << i); > + if ((msr & 1) == 0) { > /* MTRR base */ > - return valid_mtrr_type(data & 0xff); > - /* MTRR mask */ > + if (!valid_mtrr_type(data & 0xff)) > + return false; > + mask |= 0xf00; > + } else > + /* MTRR mask */ > + mask |= 0x7ff; > + if (data & mask) { > + kvm_inject_gp(vcpu, 0); > + return false; > + } > + > return true; > } > >