[PATCH v2 3/7] KVM: x86: Add kvm_is_linear_rip

Jan Kiszka
2010-02-23T16:48:18Z

Based on Gleb's suggestion: Add a helper kvm_is_linear_rip that matches
a given linear RIP against the current one. Use this for guest
single-stepping, more users will follow.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---
arch/x86/include/asm/kvm_host.h | 4 +++-
arch/x86/kvm/x86.c | 21 +++++++++++++--------
2 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index d46e791..502fff1 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -362,8 +362,8 @@ struct kvm_vcpu_arch {
u64 *mce_banks;

/* used for guest single stepping over the given code position */
- u16 singlestep_cs;
unsigned long singlestep_rip;
+
/* fields used by HYPER-V emulation */
u64 hv_vapic;
};
@@ -820,4 +820,6 @@ int kvm_cpu_get_interrupt(struct kvm_vcpu *v);
void kvm_define_shared_msr(unsigned index, u32 msr);
void kvm_set_shared_msr(unsigned index, u64 val, u64 mask);

+bool kvm_is_linear_rip(struct kvm_vcpu *vcpu, unsigned long linear_rip);
+
#endif /* _ASM_X86_KVM_HOST_H */
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index e25a522..1a97c43 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5390,11 +5390,9 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
vcpu->arch.switch_db_regs = (vcpu->arch.dr7 & DR7_BP_EN_MASK);
}

- if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) {
- vcpu->arch.singlestep_cs =
- get_segment_selector(vcpu, VCPU_SREG_CS);
- vcpu->arch.singlestep_rip = kvm_rip_read(vcpu);
- }
+ if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP)
+ vcpu->arch.singlestep_rip = kvm_rip_read(vcpu) +
+ get_segment_base(vcpu, VCPU_SREG_CS);

/*
* Trigger an rflags update that will inject or remove the trace
@@ -5885,6 +5883,15 @@ 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 current_rip = kvm_rip_read(vcpu) +
+ get_segment_base(vcpu, VCPU_SREG_CS);
+
+ return current_rip == linear_rip;
+}
+EXPORT_SYMBOL_GPL(kvm_is_linear_rip);
+
unsigned long kvm_get_rflags(struct kvm_vcpu *vcpu)
{
unsigned long rflags;
@@ -5899,9 +5906,7 @@ EXPORT_SYMBOL_GPL(kvm_get_rflags);
void kvm_set_rflags(struct kvm_vcpu *vcpu, unsigned long rflags)
{
if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP &&
- vcpu->arch.singlestep_cs ==
- get_segment_selector(vcpu, VCPU_SREG_CS) &&
- vcpu->arch.singlestep_rip == kvm_rip_read(vcpu))
+ kvm_is_linear_rip(vcpu, vcpu->arch.singlestep_rip))
rflags |= X86_EFLAGS_TF | X86_EFLAGS_RF;
kvm_x86_ops->set_rflags(vcpu, rflags);
}
--
1.6.0.2