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 <namit@xxxxxxxxxxxxxxxxx>
---
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 3ac8076..904535f 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 8f81bae..42106be 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -5185,9 +5185,7 @@ 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 e885029..773c17e 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);
--
1.9.1
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