KVM: x86: Add kvm_skip_emulated_instruction and use it.
kvm_skip_emulated_instruction calls both
kvm_x86_ops->skip_emulated_instruction and kvm_vcpu_check_singlestep,
skipping the emulated instruction and generating a trap if necessary.
Replacing skip_emulated_instruction calls with
kvm_skip_emulated_instruction is straightforward, except for:
- ICEBP, which is already inside a trap, so avoid triggering another trap.
- Instructions that can trigger exits to userspace, such as the IO insns,
MOVs to CR8, and HALT. If kvm_skip_emulated_instruction does trigger a
KVM_GUESTDBG_SINGLESTEP exit, and the handling code for
IN/OUT/MOV CR8/HALT also triggers an exit to userspace, the latter will
take precedence. The singlestep will be triggered again on the next
instruction, which is the current behavior.
- Task switch instructions which would require additional handling (e.g.
the task switch bit) and are instead left alone.
- Cases where VMLAUNCH/VMRESUME do not proceed to the next instruction,
which do not trigger singlestep traps as mentioned previously.
Signed-off-by: Kyle Huey <khuey@kylehuey.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index ec59301..7b38c5e 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -425,12 +425,14 @@
}
EXPORT_SYMBOL_GPL(kvm_requeue_exception);
-void kvm_complete_insn_gp(struct kvm_vcpu *vcpu, int err)
+int kvm_complete_insn_gp(struct kvm_vcpu *vcpu, int err)
{
if (err)
kvm_inject_gp(vcpu, 0);
else
- kvm_x86_ops->skip_emulated_instruction(vcpu);
+ return kvm_skip_emulated_instruction(vcpu);
+
+ return 1;
}
EXPORT_SYMBOL_GPL(kvm_complete_insn_gp);
@@ -4813,8 +4815,8 @@
int kvm_emulate_wbinvd(struct kvm_vcpu *vcpu)
{
- kvm_x86_ops->skip_emulated_instruction(vcpu);
- return kvm_emulate_wbinvd_noskip(vcpu);
+ kvm_emulate_wbinvd_noskip(vcpu);
+ return kvm_skip_emulated_instruction(vcpu);
}
EXPORT_SYMBOL_GPL(kvm_emulate_wbinvd);
@@ -5430,6 +5432,17 @@
}
}
+int kvm_skip_emulated_instruction(struct kvm_vcpu *vcpu)
+{
+ unsigned long rflags = kvm_x86_ops->get_rflags(vcpu);
+ int r = EMULATE_DONE;
+
+ kvm_x86_ops->skip_emulated_instruction(vcpu);
+ kvm_vcpu_check_singlestep(vcpu, rflags, &r);
+ return r == EMULATE_DONE;
+}
+EXPORT_SYMBOL_GPL(kvm_skip_emulated_instruction);
+
static bool kvm_vcpu_check_breakpoint(struct kvm_vcpu *vcpu, int *r)
{
if (unlikely(vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP) &&
@@ -6007,8 +6020,12 @@
int kvm_emulate_halt(struct kvm_vcpu *vcpu)
{
- kvm_x86_ops->skip_emulated_instruction(vcpu);
- return kvm_vcpu_halt(vcpu);
+ int ret = kvm_skip_emulated_instruction(vcpu);
+ /*
+ * TODO: we might be squashing a GUESTDBG_SINGLESTEP-triggered
+ * KVM_EXIT_DEBUG here.
+ */
+ return kvm_vcpu_halt(vcpu) && ret;
}
EXPORT_SYMBOL_GPL(kvm_emulate_halt);
@@ -6039,9 +6056,9 @@
int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
{
unsigned long nr, a0, a1, a2, a3, ret;
- int op_64_bit, r = 1;
+ int op_64_bit, r;
- kvm_x86_ops->skip_emulated_instruction(vcpu);
+ r = kvm_skip_emulated_instruction(vcpu);
if (kvm_hv_hypercall_enabled(vcpu->kvm))
return kvm_hv_hypercall(vcpu);