Messages in this thread Patch in this message | | | From | Nadav Amit <> | Subject | [PATCH 6/6] KVM: x86: check DR6/7 high-bits are clear only on long-mode | Date | Sun, 15 Jun 2014 16:13:02 +0300 |
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From: Nadav Amit <nadav.amit@gmail.com>
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 <namit@cs.technion.ac.il> --- 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); -- 1.9.1
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