From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755492Ab3G3PMQ (ORCPT ); Tue, 30 Jul 2013 11:12:16 -0400 Received: from mail-ee0-f51.google.com ([74.125.83.51]:53878 "EHLO mail-ee0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753332Ab3G3PLr (ORCPT ); Tue, 30 Jul 2013 11:11:47 -0400 From: Paolo Bonzini To: linux-kernel@vger.kernel.org Cc: gnatapov@redhat.com, kvm@vger.kernel.org Subject: [PATCH 2/3] KVM: x86: handle hardware breakpoints during emulation Date: Tue, 30 Jul 2013 17:11:35 +0200 Message-Id: <1375197096-2454-3-git-send-email-pbonzini@redhat.com> X-Mailer: git-send-email 1.8.1.4 In-Reply-To: <1375197096-2454-1-git-send-email-pbonzini@redhat.com> References: <1375197096-2454-1-git-send-email-pbonzini@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This lets debugging work better during emulation of invalid guest state. The check is done before emulating the instruction, and (in the case of guest debugging) reuses EMULATE_DO_MMIO to exit with KVM_EXIT_DEBUG. Signed-off-by: Paolo Bonzini --- arch/x86/kvm/x86.c | 66 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 66 insertions(+) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index c2a0674..1368cf5 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4956,6 +4956,62 @@ static bool retry_instruction(struct x86_emulate_ctxt *ctxt, static int complete_emulated_mmio(struct kvm_vcpu *vcpu); static int complete_emulated_pio(struct kvm_vcpu *vcpu); +static int kvm_vcpu_check_hw_bp(unsigned long addr, u32 type, u32 dr7, + unsigned long *db) +{ + u32 dr6 = 0; + int i; + u32 enable, rwlen; + + enable = dr7; + rwlen = dr7 >> 16; + for (i = 0; i < 4; i++, enable >>= 2, rwlen >>= 4) + if ((enable & 3) && (rwlen & 15) == type && db[i] == addr) + dr6 |= (1 << i); + return dr6; +} + +static bool kvm_vcpu_check_breakpoint(struct kvm_vcpu *vcpu, int *r) +{ + struct kvm_run *kvm_run = vcpu->run; + unsigned long eip = vcpu->arch.emulate_ctxt.eip; + u32 dr6 = 0; + + if (unlikely(vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP) && + (vcpu->arch.guest_debug_dr7 & DR7_BP_EN_MASK)) { + dr6 = kvm_vcpu_check_hw_bp(eip, 0, + vcpu->arch.guest_debug_dr7, + vcpu->arch.eff_db); + + if (dr6 != 0) { + kvm_run->debug.arch.dr6 = dr6 | DR6_FIXED_1; + kvm_run->debug.arch.pc = kvm_rip_read(vcpu) + + get_segment_base(vcpu, VCPU_SREG_CS); + + kvm_run->debug.arch.exception = DB_VECTOR; + kvm_run->exit_reason = KVM_EXIT_DEBUG; + *r = EMULATE_USER_EXIT; + return true; + } + } + + if (unlikely(vcpu->arch.dr7 & DR7_BP_EN_MASK)) { + dr6 = kvm_vcpu_check_hw_bp(eip, 0, + vcpu->arch.dr7, + vcpu->arch.db); + + if (dr6 != 0) { + vcpu->arch.dr6 &= ~15; + vcpu->arch.dr6 |= dr6; + kvm_queue_exception(vcpu, DB_VECTOR); + *r = EMULATE_DONE; + return true; + } + } + + return false; +} + int x86_emulate_instruction(struct kvm_vcpu *vcpu, unsigned long cr2, int emulation_type, @@ -4976,6 +5032,16 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu, if (!(emulation_type & EMULTYPE_NO_DECODE)) { init_emulate_ctxt(vcpu); + + /* + * We will reenter on the same instruction since + * we do not set complete_userspace_io. This does not + * handle watchpoints yet, those would be handled in + * the emulate_ops. + */ + if (kvm_vcpu_check_breakpoint(vcpu, &r)) + return r; + ctxt->interruptibility = 0; ctxt->have_exception = false; ctxt->perm_ok = false; -- 1.8.1.4