From: Hou Wenlong When emulating a MOV DR instruction, honor KVM_GUESTDBG_USE_HW_BP when checking DR7.GD, and if there is a general-detect #DB, route it to host userspace as appropriate. Consulting only the guest's actual DR7 causes KVM to fail to report a DR access to userspace (assuming the guest itself doesn't have DR7.GD=1). Fixes: ae675ef01cd8 ("KVM: x86: Wire-up hardware breakpoints for guest debugging") Suggested-by: Lai Jiangshan Signed-off-by: Hou Wenlong [sean: only expose effective DR7 to emulator, massage changelog] Signed-off-by: Sean Christopherson --- arch/x86/kvm/emulate.c | 2 +- arch/x86/kvm/kvm_emulate.h | 1 + arch/x86/kvm/x86.c | 41 ++++++++++++++++++++++++++++++-------- 3 files changed, 35 insertions(+), 9 deletions(-) diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index 510244555a74..917a521c299f 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -3848,7 +3848,7 @@ static int check_dr_read(struct x86_emulate_ctxt *ctxt) if ((cr4 & X86_CR4_DE) && (dr == 4 || dr == 5)) return emulate_ud(ctxt); - if (ctxt->ops->get_dr(ctxt, 7) & DR7_GD) + if (ctxt->ops->get_eff_dr7(ctxt) & DR7_GD) return emulate_db(ctxt, DR6_BD); return X86EMUL_CONTINUE; diff --git a/arch/x86/kvm/kvm_emulate.h b/arch/x86/kvm/kvm_emulate.h index bb2a2aee0e13..33bfc9aa948e 100644 --- a/arch/x86/kvm/kvm_emulate.h +++ b/arch/x86/kvm/kvm_emulate.h @@ -215,6 +215,7 @@ struct x86_emulate_ops { ulong (*get_cr)(struct x86_emulate_ctxt *ctxt, int cr); int (*set_cr)(struct x86_emulate_ctxt *ctxt, int cr, ulong val); int (*cpl)(struct x86_emulate_ctxt *ctxt); + ulong (*get_eff_dr7)(struct x86_emulate_ctxt *ctxt); ulong (*get_dr)(struct x86_emulate_ctxt *ctxt, int dr); int (*set_dr)(struct x86_emulate_ctxt *ctxt, int dr, ulong value); int (*set_msr_with_filter)(struct x86_emulate_ctxt *ctxt, u32 msr_index, u64 data); diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 8a862d39302c..8b07bd2f8310 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1601,6 +1601,14 @@ unsigned long kvm_get_dr(struct kvm_vcpu *vcpu, int dr) } EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_get_dr); +static unsigned long kvm_get_eff_dr7(struct kvm_vcpu *vcpu) +{ + if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP) + return vcpu->arch.guest_debug_dr7; + + return vcpu->arch.dr7; +} + int kvm_emulate_rdpmc(struct kvm_vcpu *vcpu) { u32 pmc = kvm_rcx_read(vcpu); @@ -8548,6 +8556,11 @@ static void emulator_wbinvd(struct x86_emulate_ctxt *ctxt) kvm_emulate_wbinvd_noskip(emul_to_vcpu(ctxt)); } +static unsigned long emulator_get_eff_dr7(struct x86_emulate_ctxt *ctxt) +{ + return kvm_get_eff_dr7(emul_to_vcpu(ctxt)); +} + static unsigned long emulator_get_dr(struct x86_emulate_ctxt *ctxt, int dr) { return kvm_get_dr(emul_to_vcpu(ctxt), dr); @@ -8930,6 +8943,7 @@ static const struct x86_emulate_ops emulate_ops = { .get_cr = emulator_get_cr, .set_cr = emulator_set_cr, .cpl = emulator_get_cpl, + .get_eff_dr7 = emulator_get_eff_dr7, .get_dr = emulator_get_dr, .set_dr = emulator_set_dr, .set_msr_with_filter = emulator_set_msr_with_filter, @@ -8976,23 +8990,36 @@ static void toggle_interruptibility(struct kvm_vcpu *vcpu, u32 mask) } } -static void kvm_inject_emulated_db(struct kvm_vcpu *vcpu, unsigned long dr6) +static int kvm_inject_emulated_db(struct kvm_vcpu *vcpu, unsigned long dr6) { + struct kvm_run *kvm_run = vcpu->run; + + if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP) { + kvm_run->debug.arch.dr6 = dr6 | DR6_ACTIVE_LOW; + kvm_run->debug.arch.pc = kvm_get_linear_rip(vcpu); + kvm_run->debug.arch.exception = DB_VECTOR; + kvm_run->exit_reason = KVM_EXIT_DEBUG; + return 0; + } + kvm_queue_exception_p(vcpu, DB_VECTOR, dr6); + return 1; } -static void inject_emulated_exception(struct kvm_vcpu *vcpu) +static int inject_emulated_exception(struct kvm_vcpu *vcpu) { struct x86_exception *ex = &vcpu->arch.emulate_ctxt->exception; if (ex->vector == DB_VECTOR) - kvm_inject_emulated_db(vcpu, ex->dr6); - else if (ex->vector == PF_VECTOR) + return kvm_inject_emulated_db(vcpu, ex->dr6); + + if (ex->vector == PF_VECTOR) kvm_inject_emulated_page_fault(vcpu, ex); else if (ex->error_code_valid) kvm_queue_exception_e(vcpu, ex->vector, ex->error_code); else kvm_queue_exception(vcpu, ex->vector); + return 1; } static struct x86_emulate_ctxt *alloc_emulate_ctxt(struct kvm_vcpu *vcpu) @@ -9501,8 +9528,7 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, */ WARN_ON_ONCE(ctxt->exception.vector == UD_VECTOR || exception_type(ctxt->exception.vector) == EXCPT_TRAP); - inject_emulated_exception(vcpu); - return 1; + return inject_emulated_exception(vcpu); } return handle_emulation_failure(vcpu, emulation_type); } @@ -9597,8 +9623,7 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, if (ctxt->have_exception) { WARN_ON_ONCE(vcpu->mmio_needed && !vcpu->mmio_is_write); vcpu->mmio_needed = false; - r = 1; - inject_emulated_exception(vcpu); + r = inject_emulated_exception(vcpu); } else if (vcpu->arch.pio.count) { if (!vcpu->arch.pio.in) { /* FIXME: return into emulator if single-stepping. */ -- 2.54.0.563.g4f69b47b94-goog