From 82b32774c2d00c0a12ab182c67e32e0b5e5e580a Mon Sep 17 00:00:00 2001 From: Nadav Amit Date: Sun, 2 Nov 2014 11:54:45 +0200 Subject: [PATCH] KVM: x86: Breakpoints do not consider CS.base x86 debug registers hold a linear address. Therefore, breakpoints detection should consider CS.base, and check whether instruction linear address equals (CS.base + RIP). This patch introduces a function to evaluate RIP linear address and uses it for breakpoints detection. Signed-off-by: Nadav Amit Signed-off-by: Paolo Bonzini --- arch/x86/include/asm/kvm_host.h | 1 + arch/x86/kvm/vmx.c | 4 +--- arch/x86/kvm/x86.c | 29 ++++++++++++++++------------- 3 files changed, 18 insertions(+), 16 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 3ac807646911..904535fe825e 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1067,6 +1067,7 @@ void kvm_arch_mmu_notifier_invalidate_page(struct kvm *kvm, void kvm_define_shared_msr(unsigned index, u32 msr); int kvm_set_shared_msr(unsigned index, u64 val, u64 mask); +unsigned long kvm_get_linear_rip(struct kvm_vcpu *vcpu); bool kvm_is_linear_rip(struct kvm_vcpu *vcpu, unsigned long linear_rip); void kvm_arch_async_page_not_present(struct kvm_vcpu *vcpu, diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index ad5e0806e1e1..284f5c2fdf0b 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -5118,9 +5118,7 @@ static int handle_dr(struct kvm_vcpu *vcpu) if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP) { vcpu->run->debug.arch.dr6 = vcpu->arch.dr6; vcpu->run->debug.arch.dr7 = dr7; - vcpu->run->debug.arch.pc = - vmcs_readl(GUEST_CS_BASE) + - vmcs_readl(GUEST_RIP); + vcpu->run->debug.arch.pc = kvm_get_linear_rip(vcpu); vcpu->run->debug.arch.exception = DB_VECTOR; vcpu->run->exit_reason = KVM_EXIT_DEBUG; return 0; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index e8850295031f..773c17ec42dd 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -5207,21 +5207,17 @@ static void kvm_vcpu_check_singlestep(struct kvm_vcpu *vcpu, unsigned long rflag 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, + struct kvm_run *kvm_run = vcpu->run; + unsigned long eip = kvm_get_linear_rip(vcpu); + u32 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 | DR6_RTM; - kvm_run->debug.arch.pc = kvm_rip_read(vcpu) + - get_segment_base(vcpu, VCPU_SREG_CS); - + kvm_run->debug.arch.pc = eip; kvm_run->debug.arch.exception = DB_VECTOR; kvm_run->exit_reason = KVM_EXIT_DEBUG; *r = EMULATE_USER_EXIT; @@ -5231,7 +5227,8 @@ static bool kvm_vcpu_check_breakpoint(struct kvm_vcpu *vcpu, int *r) if (unlikely(vcpu->arch.dr7 & DR7_BP_EN_MASK) && !(kvm_get_rflags(vcpu) & X86_EFLAGS_RF)) { - dr6 = kvm_vcpu_check_hw_bp(eip, 0, + unsigned long eip = kvm_get_linear_rip(vcpu); + u32 dr6 = kvm_vcpu_check_hw_bp(eip, 0, vcpu->arch.dr7, vcpu->arch.db); @@ -7538,12 +7535,18 @@ int kvm_arch_interrupt_allowed(struct kvm_vcpu *vcpu) return kvm_x86_ops->interrupt_allowed(vcpu); } -bool kvm_is_linear_rip(struct kvm_vcpu *vcpu, unsigned long linear_rip) +unsigned long kvm_get_linear_rip(struct kvm_vcpu *vcpu) { - unsigned long current_rip = kvm_rip_read(vcpu) + - get_segment_base(vcpu, VCPU_SREG_CS); + if (is_64_bit_mode(vcpu)) + return kvm_rip_read(vcpu); + return (u32)(get_segment_base(vcpu, VCPU_SREG_CS) + + kvm_rip_read(vcpu)); +} +EXPORT_SYMBOL_GPL(kvm_get_linear_rip); - return current_rip == linear_rip; +bool kvm_is_linear_rip(struct kvm_vcpu *vcpu, unsigned long linear_rip) +{ + return kvm_get_linear_rip(vcpu) == linear_rip; } EXPORT_SYMBOL_GPL(kvm_is_linear_rip); -- 2.45.2