From: Nicușor Cîțu <ncitu@xxxxxxxxxxxxxxx>
This commit also ensures that only the userspace or the introspection
tool can control the #BP interception exclusively at one time.
Signed-off-by: Nicușor Cîțu <ncitu@xxxxxxxxxxxxxxx>
Signed-off-by: Adalbert Lazăr <alazar@xxxxxxxxxxxxxxx>
---
arch/x86/include/asm/kvm_host.h | 3 +
arch/x86/include/asm/kvmi_host.h | 22 +++++++
arch/x86/kvm/kvmi.c | 99 ++++++++++++++++++++++++++++++-
arch/x86/kvm/x86.c | 5 ++
virt/kvm/introspection/kvmi.c | 27 ++++++++-
virt/kvm/introspection/kvmi_int.h | 6 +-
6 files changed, 157 insertions(+), 5 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index c2176012676d..5f3b6f20718f 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -832,6 +832,9 @@ struct kvm_vcpu_arch {
/* #PF translated error code from EPT/NPT exit reason */
u64 error_code;
+
+ /* Control the interception for KVM Introspection */
+ struct kvmi_interception *kvmi;
};
struct kvm_lpage_info {
diff --git a/arch/x86/include/asm/kvmi_host.h b/arch/x86/include/asm/kvmi_host.h
index 360a57dd9019..c8b793915b84 100644
--- a/arch/x86/include/asm/kvmi_host.h
+++ b/arch/x86/include/asm/kvmi_host.h
@@ -2,10 +2,32 @@
#ifndef _ASM_X86_KVMI_HOST_H
#define _ASM_X86_KVMI_HOST_H
+struct kvmi_monitor_interception {
+ bool kvmi_intercepted;
+ bool kvm_intercepted;
+ bool (*monitor_fct)(struct kvm_vcpu *vcpu, bool enable);
+};
+
+struct kvmi_interception {
+ bool restore_interception;
+ struct kvmi_monitor_interception breakpoint;
+};
+
struct kvm_vcpu_arch_introspection {
};
struct kvm_arch_introspection {
};
+#ifdef CONFIG_KVM_INTROSPECTION
+
+bool kvmi_monitor_bp_intercept(struct kvm_vcpu *vcpu, u32 dbg);
+
+#else /* CONFIG_KVM_INTROSPECTION */
+
+static inline bool kvmi_monitor_bp_intercept(struct kvm_vcpu *vcpu, u32 dbg)
+ { return false; }
+
+#endif /* CONFIG_KVM_INTROSPECTION */
+
#endif /* _ASM_X86_KVMI_HOST_H */
diff --git a/arch/x86/kvm/kvmi.c b/arch/x86/kvm/kvmi.c
index 92314341b3a9..74fca566a44a 100644
--- a/arch/x86/kvm/kvmi.c
+++ b/arch/x86/kvm/kvmi.c
@@ -242,18 +242,71 @@ void kvmi_arch_hypercall_event(struct kvm_vcpu *vcpu)
}
}
+/*
+ * Returns true if one side (kvm or kvmi) tries to enable/disable the breakpoint
+ * interception while the other side is still tracking it.
+ */
+bool kvmi_monitor_bp_intercept(struct kvm_vcpu *vcpu, u32 dbg)
+{
+ struct kvmi_interception *arch_vcpui = READ_ONCE(vcpu->arch.kvmi);
+ u32 bp_mask = KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_SW_BP;
+ bool enable = false;
+
+ if ((dbg & bp_mask) == bp_mask)
+ enable = true;
+
+ return (arch_vcpui && arch_vcpui->breakpoint.monitor_fct(vcpu, enable));
+}
+EXPORT_SYMBOL(kvmi_monitor_bp_intercept);
+
+static bool monitor_bp_fct_kvmi(struct kvm_vcpu *vcpu, bool enable)
+{
+ if (enable) {
+ if (kvm_x86_ops->bp_intercepted(vcpu))
+ return true;
+ } else if (!vcpu->arch.kvmi->breakpoint.kvmi_intercepted)
+ return true;
+
+ vcpu->arch.kvmi->breakpoint.kvmi_intercepted = enable;
+
+ return false;
+}
+
+static bool monitor_bp_fct_kvm(struct kvm_vcpu *vcpu, bool enable)
+{
+ if (enable) {
+ if (kvm_x86_ops->bp_intercepted(vcpu))
+ return true;
+ } else if (!vcpu->arch.kvmi->breakpoint.kvm_intercepted)
+ return true;
+
+ vcpu->arch.kvmi->breakpoint.kvm_intercepted = enable;
+
+ return false;
+}
+
static int kvmi_control_bp_intercept(struct kvm_vcpu *vcpu, bool enable)
{
struct kvm_guest_debug dbg = {};
int err = 0;
+ vcpu->arch.kvmi->breakpoint.monitor_fct = monitor_bp_fct_kvmi;
if (enable)
dbg.control = KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_SW_BP;
err = kvm_arch_vcpu_set_guest_debug(vcpu, &dbg);
+ vcpu->arch.kvmi->breakpoint.monitor_fct = monitor_bp_fct_kvm;
return err;
}
+static void kvmi_arch_disable_bp_intercept(struct kvm_vcpu *vcpu)
+{
+ kvmi_control_bp_intercept(vcpu, false);
+
+ vcpu->arch.kvmi->breakpoint.kvmi_intercepted = false;
+ vcpu->arch.kvmi->breakpoint.kvm_intercepted = false;
+}
+
int kvmi_arch_cmd_control_intercept(struct kvm_vcpu *vcpu,
unsigned int event_id, bool enable)
{
@@ -290,6 +343,50 @@ void kvmi_arch_breakpoint_event(struct kvm_vcpu *vcpu, u64 gva, u8 insn_len)
}
}
-void kvmi_arch_restore_interception(struct kvm_vcpu *vcpu)
+bool kvmi_arch_restore_interception(struct kvm_vcpu *vcpu)
{
+ struct kvmi_interception *arch_vcpui = vcpu->arch.kvmi;
+
+ if (!arch_vcpui || !arch_vcpui->restore_interception)
+ return false;
+
+ kvmi_arch_disable_bp_intercept(vcpu);
+
+ return true;
+}
+
+bool kvmi_arch_vcpu_alloc(struct kvm_vcpu *vcpu)
+{
+ struct kvmi_interception *arch_vcpui;
+
+ arch_vcpui = kzalloc(sizeof(*arch_vcpui), GFP_KERNEL);
+ if (!arch_vcpui)
+ return false;
+
+ arch_vcpui->breakpoint.monitor_fct = monitor_bp_fct_kvm;
+
+ /* pair with kvmi_monitor_bp_intercept() */
+ smp_wmb();
+ WRITE_ONCE(vcpu->arch.kvmi, arch_vcpui);
+
+ return true;
+}
+
+void kvmi_arch_vcpu_free(struct kvm_vcpu *vcpu)
+{
+ kfree(vcpu->arch.kvmi);
+ WRITE_ONCE(vcpu->arch.kvmi, NULL);
+}
+
+bool kvmi_arch_vcpu_introspected(struct kvm_vcpu *vcpu)
+{
+ return !!READ_ONCE(vcpu->arch.kvmi);
+}
+
+void kvmi_arch_request_restore_interception(struct kvm_vcpu *vcpu)
+{
+ struct kvmi_interception *arch_vcpui = READ_ONCE(vcpu->arch.kvmi);
+
+ if (arch_vcpui)
+ arch_vcpui->restore_interception = true;
}
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index bad66420f054..31273c4c7f8d 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9169,6 +9169,11 @@ int kvm_arch_vcpu_set_guest_debug(struct kvm_vcpu *vcpu,
kvm_queue_exception(vcpu, BP_VECTOR);
}
+ if (kvmi_monitor_bp_intercept(vcpu, dbg->control)) {
+ r = -EBUSY;
+ goto out;
+ }
+
/*
* Read rflags as long as potentially injected trace flags are still
* filtered out.
diff --git a/virt/kvm/introspection/kvmi.c b/virt/kvm/introspection/kvmi.c
index 32516cc70928..7ea0512bc580 100644
--- a/virt/kvm/introspection/kvmi.c
+++ b/virt/kvm/introspection/kvmi.c
@@ -167,7 +167,7 @@ static bool alloc_vcpui(struct kvm_vcpu *vcpu)
vcpu->kvmi = vcpui;
- return true;
+ return kvmi_arch_vcpu_alloc(vcpu);
}
static int create_vcpui(struct kvm_vcpu *vcpu)
@@ -200,6 +200,7 @@ static void free_vcpui(struct kvm_vcpu *vcpu)
kfree(vcpui);
vcpu->kvmi = NULL;
+ kvmi_arch_request_restore_interception(vcpu);
kvmi_make_request(vcpu, false);
}
@@ -219,6 +220,7 @@ void kvmi_vcpu_uninit(struct kvm_vcpu *vcpu)
{
mutex_lock(&vcpu->kvm->kvmi_lock);
free_vcpui(vcpu);
+ kvmi_arch_vcpu_free(vcpu);
mutex_unlock(&vcpu->kvm->kvmi_lock);
}
@@ -358,6 +360,21 @@ static int kvmi_recv_thread(void *arg)
return 0;
}
+static bool ready_to_hook(struct kvm *kvm)
+{
+ struct kvm_vcpu *vcpu;
+ int i;
+
+ if (kvm->kvmi)
+ return false;
+
+ kvm_for_each_vcpu(i, vcpu, kvm)
+ if (kvmi_arch_vcpu_introspected(vcpu))
+ return false;
+
+ return true;
+}
+
int kvmi_hook(struct kvm *kvm, const struct kvm_introspection_hook *hook)
{
struct kvm_introspection *kvmi;
@@ -365,7 +382,7 @@ int kvmi_hook(struct kvm *kvm, const struct kvm_introspection_hook *hook)
mutex_lock(&kvm->kvmi_lock);
- if (kvm->kvmi) {
+ if (!ready_to_hook(kvm)) {
err = -EEXIST;
goto out;
}
@@ -806,7 +823,11 @@ void kvmi_handle_requests(struct kvm_vcpu *vcpu)
kvmi_put(vcpu->kvm);
out:
- kvmi_arch_restore_interception(vcpu);
+ if (kvmi_arch_restore_interception(vcpu)) {
+ mutex_lock(&vcpu->kvm->kvmi_lock);
+ kvmi_arch_vcpu_free(vcpu);
+ mutex_unlock(&vcpu->kvm->kvmi_lock);
+ }
}
int kvmi_cmd_vcpu_pause(struct kvm_vcpu *vcpu, bool wait)
diff --git a/virt/kvm/introspection/kvmi_int.h b/virt/kvm/introspection/kvmi_int.h
index 0fc622b2c96d..7024bfa3df61 100644
--- a/virt/kvm/introspection/kvmi_int.h
+++ b/virt/kvm/introspection/kvmi_int.h
@@ -65,7 +65,11 @@ int kvmi_cmd_vcpu_set_registers(struct kvm_vcpu *vcpu,
const struct kvm_regs *regs);
/* arch */
-void kvmi_arch_restore_interception(struct kvm_vcpu *vcpu);
+bool kvmi_arch_vcpu_alloc(struct kvm_vcpu *vcpu);
+void kvmi_arch_vcpu_free(struct kvm_vcpu *vcpu);
+bool kvmi_arch_vcpu_introspected(struct kvm_vcpu *vcpu);
+bool kvmi_arch_restore_interception(struct kvm_vcpu *vcpu);
+void kvmi_arch_request_restore_interception(struct kvm_vcpu *vcpu);
int kvmi_arch_cmd_vcpu_get_info(struct kvm_vcpu *vcpu,
struct kvmi_vcpu_get_info_reply *rpl);
void kvmi_arch_setup_event(struct kvm_vcpu *vcpu, struct kvmi_event *ev);
