From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [PATCH 6/6] KVM: x86: check DR6/7 high-bits are clear only on long-mode Date: Mon, 16 Jun 2014 12:17:35 +0200 Message-ID: <539EC43F.607@redhat.com> References: <1402837982-24959-1-git-send-email-namit@cs.technion.ac.il> <1402837982-24959-7-git-send-email-namit@cs.technion.ac.il> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit Cc: gleb@kernel.org, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Nadav Amit To: Nadav Amit Return-path: In-Reply-To: <1402837982-24959-7-git-send-email-namit@cs.technion.ac.il> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org Il 15/06/2014 15:13, Nadav Amit ha scritto: > From: Nadav Amit > > When the guest sets DR6 and DR7, KVM asserts the high 32-bits are clear, and > otherwise injects a #GP exception. This exception should only be injected only > if running in long-mode. > > Signed-off-by: Nadav Amit > --- > arch/x86/kvm/x86.c | 13 +++++++++++-- > 1 file changed, 11 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 57eac30..71fe841 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -756,6 +756,15 @@ static void kvm_update_dr7(struct kvm_vcpu *vcpu) > vcpu->arch.switch_db_regs |= KVM_DEBUGREG_BP_ENABLED; > } > > +static bool is_64_bit_mode(struct kvm_vcpu *vcpu) > +{ > + int cs_db, cs_l; > + if (!is_long_mode(vcpu)) > + return false; > + kvm_x86_ops->get_cs_db_l_bits(vcpu, &cs_db, &cs_l); > + return cs_l; > +} > + > static int __kvm_set_dr(struct kvm_vcpu *vcpu, int dr, unsigned long val) > { > switch (dr) { > @@ -769,7 +778,7 @@ static int __kvm_set_dr(struct kvm_vcpu *vcpu, int dr, unsigned long val) > return 1; /* #UD */ > /* fall through */ > case 6: > - if (val & 0xffffffff00000000ULL) > + if ((val & 0xffffffff00000000ULL) && is_64_bit_mode(vcpu)) > return -1; /* #GP */ > vcpu->arch.dr6 = (val & DR6_VOLATILE) | DR6_FIXED_1; > kvm_update_dr6(vcpu); > @@ -779,7 +788,7 @@ static int __kvm_set_dr(struct kvm_vcpu *vcpu, int dr, unsigned long val) > return 1; /* #UD */ > /* fall through */ > default: /* 7 */ > - if (val & 0xffffffff00000000ULL) > + if ((val & 0xffffffff00000000ULL) && is_64_bit_mode(vcpu)) > return -1; /* #GP */ > vcpu->arch.dr7 = (val & DR7_VOLATILE) | DR7_FIXED_1; > kvm_update_dr7(vcpu); > Do you get this if the input register has bit 31 set? Paolo