diff options
| author | Nadav Amit <namit@cs.technion.ac.il> | 2014-07-15 17:37:46 +0300 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2014-07-21 17:17:52 +0200 |
| commit | 6f43ed01e87c8a8dbd8c826eaf0f714c1342c039 (patch) | |
| tree | 96064816637d154889b1b4bea5e6c5dd6062c9bf /arch/x86/kvm/x86.c | |
| parent | 9a2a05b9ed618b1bb6d4cbec0c2e1f80d6636609 (diff) | |
KVM: x86: DR6/7.RTM cannot be written
Haswell and newer Intel CPUs have support for RTM, and in that case DR6.RTM is
not fixed to 1 and DR7.RTM is not fixed to zero. That is not the case in the
current KVM implementation. This bug is apparent only if the MOV-DR instruction
is emulated or the host also debugs the guest.
This patch is a partial fix which enables DR6.RTM and DR7.RTM to be cleared and
set respectively. It also sets DR6.RTM upon every debug exception. Obviously,
it is not a complete fix, as debugging of RTM is still unsupported.
Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm/x86.c')
| -rw-r--r-- | arch/x86/kvm/x86.c | 22 |
1 files changed, 16 insertions, 6 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index cc4f65f39b87..08c48a3c7c3a 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -759,6 +759,15 @@ static void kvm_update_dr7(struct kvm_vcpu *vcpu) vcpu->arch.switch_db_regs |= KVM_DEBUGREG_BP_ENABLED; } +static u64 kvm_dr6_fixed(struct kvm_vcpu *vcpu) +{ + u64 fixed = DR6_FIXED_1; + + if (!guest_cpuid_has_rtm(vcpu)) + fixed |= DR6_RTM; + return fixed; +} + static int __kvm_set_dr(struct kvm_vcpu *vcpu, int dr, unsigned long val) { switch (dr) { @@ -774,7 +783,7 @@ static int __kvm_set_dr(struct kvm_vcpu *vcpu, int dr, unsigned long val) case 6: if (val & 0xffffffff00000000ULL) return -1; /* #GP */ - vcpu->arch.dr6 = (val & DR6_VOLATILE) | DR6_FIXED_1; + vcpu->arch.dr6 = (val & DR6_VOLATILE) | kvm_dr6_fixed(vcpu); kvm_update_dr6(vcpu); break; case 5: @@ -5115,7 +5124,8 @@ static void kvm_vcpu_check_singlestep(struct kvm_vcpu *vcpu, unsigned long rflag */ if (unlikely(rflags & X86_EFLAGS_TF)) { if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) { - kvm_run->debug.arch.dr6 = DR6_BS | DR6_FIXED_1; + kvm_run->debug.arch.dr6 = DR6_BS | DR6_FIXED_1 | + DR6_RTM; kvm_run->debug.arch.pc = vcpu->arch.singlestep_rip; kvm_run->debug.arch.exception = DB_VECTOR; kvm_run->exit_reason = KVM_EXIT_DEBUG; @@ -5128,7 +5138,7 @@ static void kvm_vcpu_check_singlestep(struct kvm_vcpu *vcpu, unsigned long rflag * cleared by the processor". */ vcpu->arch.dr6 &= ~15; - vcpu->arch.dr6 |= DR6_BS; + vcpu->arch.dr6 |= DR6_BS | DR6_RTM; kvm_queue_exception(vcpu, DB_VECTOR); } } @@ -5147,7 +5157,7 @@ static bool kvm_vcpu_check_breakpoint(struct kvm_vcpu *vcpu, int *r) vcpu->arch.eff_db); if (dr6 != 0) { - kvm_run->debug.arch.dr6 = dr6 | DR6_FIXED_1; + kvm_run->debug.arch.dr6 = dr6 | DR6_FIXED_1 | DR6_RTM; kvm_run->debug.arch.pc = kvm_rip_read(vcpu) + get_segment_base(vcpu, VCPU_SREG_CS); @@ -5166,7 +5176,7 @@ static bool kvm_vcpu_check_breakpoint(struct kvm_vcpu *vcpu, int *r) if (dr6 != 0) { vcpu->arch.dr6 &= ~15; - vcpu->arch.dr6 |= dr6; + vcpu->arch.dr6 |= dr6 | DR6_RTM; kvm_queue_exception(vcpu, DB_VECTOR); *r = EMULATE_DONE; return true; @@ -6866,7 +6876,7 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu) kvm_clear_exception_queue(vcpu); memset(vcpu->arch.db, 0, sizeof(vcpu->arch.db)); - vcpu->arch.dr6 = DR6_FIXED_1; + vcpu->arch.dr6 = DR6_INIT; kvm_update_dr6(vcpu); vcpu->arch.dr7 = DR7_FIXED_1; kvm_update_dr7(vcpu); |