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KVM: x86: Breakpoints do not consider CS.base

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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@cs.technion.ac.il>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Nadav Amit 2014-11-02 11:54:45 +02:00 committed by Paolo Bonzini
parent 7305eb5d8c
commit 82b32774c2
3 changed files with 18 additions and 16 deletions
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1
arch/x86/include/asm/kvm_host.h
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@ -1067,6 +1067,7 @@ void kvm_arch_mmu_notifier_invalidate_page(struct kvm *kvm,
void kvm_define_shared_msr(unsigned index, u32 msr); void kvm_define_shared_msr(unsigned index, u32 msr);
int kvm_set_shared_msr(unsigned index, u64 val, u64 mask); 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); bool kvm_is_linear_rip(struct kvm_vcpu *vcpu, unsigned long linear_rip);
void kvm_arch_async_page_not_present(struct kvm_vcpu *vcpu, void kvm_arch_async_page_not_present(struct kvm_vcpu *vcpu,

4
arch/x86/kvm/vmx.c
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@ -5118,9 +5118,7 @@ static int handle_dr(struct kvm_vcpu *vcpu)
if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP) { if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP) {
vcpu->run->debug.arch.dr6 = vcpu->arch.dr6; vcpu->run->debug.arch.dr6 = vcpu->arch.dr6;
vcpu->run->debug.arch.dr7 = dr7; vcpu->run->debug.arch.dr7 = dr7;
vcpu->run->debug.arch.pc = vcpu->run->debug.arch.pc = kvm_get_linear_rip(vcpu);
vmcs_readl(GUEST_CS_BASE) +
vmcs_readl(GUEST_RIP);
vcpu->run->debug.arch.exception = DB_VECTOR; vcpu->run->debug.arch.exception = DB_VECTOR;
vcpu->run->exit_reason = KVM_EXIT_DEBUG; vcpu->run->exit_reason = KVM_EXIT_DEBUG;
return 0; return 0;

29
arch/x86/kvm/x86.c
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@ -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) 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) && if (unlikely(vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP) &&
(vcpu->arch.guest_debug_dr7 & DR7_BP_EN_MASK)) { (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.guest_debug_dr7,
vcpu->arch.eff_db); vcpu->arch.eff_db);
if (dr6 != 0) { if (dr6 != 0) {
kvm_run->debug.arch.dr6 = dr6 | DR6_FIXED_1 | DR6_RTM; kvm_run->debug.arch.dr6 = dr6 | DR6_FIXED_1 | DR6_RTM;
kvm_run->debug.arch.pc = kvm_rip_read(vcpu) + kvm_run->debug.arch.pc = eip;
get_segment_base(vcpu, VCPU_SREG_CS);
kvm_run->debug.arch.exception = DB_VECTOR; kvm_run->debug.arch.exception = DB_VECTOR;
kvm_run->exit_reason = KVM_EXIT_DEBUG; kvm_run->exit_reason = KVM_EXIT_DEBUG;
*r = EMULATE_USER_EXIT; *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) && if (unlikely(vcpu->arch.dr7 & DR7_BP_EN_MASK) &&
!(kvm_get_rflags(vcpu) & X86_EFLAGS_RF)) { !(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.dr7,
vcpu->arch.db); vcpu->arch.db);
@ -7538,12 +7535,18 @@ int kvm_arch_interrupt_allowed(struct kvm_vcpu *vcpu)
return kvm_x86_ops->interrupt_allowed(vcpu); return kvm_x86_ops->interrupt_allowed(vcpu);
} }
unsigned long kvm_get_linear_rip(struct kvm_vcpu *vcpu)
{
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);
bool kvm_is_linear_rip(struct kvm_vcpu *vcpu, unsigned long linear_rip) bool kvm_is_linear_rip(struct kvm_vcpu *vcpu, unsigned long linear_rip)
{ {
unsigned long current_rip = kvm_rip_read(vcpu) + return kvm_get_linear_rip(vcpu) == linear_rip;
get_segment_base(vcpu, VCPU_SREG_CS);
return current_rip == linear_rip;
} }
EXPORT_SYMBOL_GPL(kvm_is_linear_rip); EXPORT_SYMBOL_GPL(kvm_is_linear_rip);