[PATCH v9 49/84] KVM: introspection: handle vCPU introspection requests

From: "Adalbert Lazăr" <alazar@bitdefender.com>
To: kvm@vger.kernel.org
Cc: virtualization@lists.linux-foundation.org,
	"Paolo Bonzini" <pbonzini@redhat.com>,
	"Mihai Donțu" <mdontu@bitdefender.com>,
	"Mircea Cîrjaliu" <mcirjaliu@bitdefender.com>,
	"Adalbert Lazăr" <alazar@bitdefender.com>
Subject: [PATCH v9 49/84] KVM: introspection: handle vCPU introspection requests
Date: Wed, 22 Jul 2020 00:08:47 +0300	[thread overview]
Message-ID: <20200721210922.7646-50-alazar@bitdefender.com> (raw)
In-Reply-To: <20200721210922.7646-1-alazar@bitdefender.com>

From: Mihai Donțu <mdontu@bitdefender.com>

The receiving thread dispatches the vCPU introspection commands by
adding them to the vCPU's jobs list and kicking the vCPU. Before
entering in guest, the vCPU thread checks the introspection request
(KVM_REQ_INTROSPECTION) and runs its queued jobs.

Signed-off-by: Mihai Donțu <mdontu@bitdefender.com>
Co-developed-by: Mircea Cîrjaliu <mcirjaliu@bitdefender.com>
Signed-off-by: Mircea Cîrjaliu <mcirjaliu@bitdefender.com>
Co-developed-by: Adalbert Lazăr <alazar@bitdefender.com>
Signed-off-by: Adalbert Lazăr <alazar@bitdefender.com>
---
 arch/x86/kvm/x86.c            |  3 ++
 include/linux/kvm_host.h      |  1 +
 include/linux/kvmi_host.h     |  4 +++
 virt/kvm/introspection/kvmi.c | 58 +++++++++++++++++++++++++++++++++++
 virt/kvm/kvm_main.c           |  2 ++
 5 files changed, 68 insertions(+)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index ff0d3c82de64..7f56e2149f18 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8706,6 +8706,9 @@ static int vcpu_run(struct kvm_vcpu *vcpu)
 	vcpu->arch.l1tf_flush_l1d = true;
 
 	for (;;) {
+		if (kvm_check_request(KVM_REQ_INTROSPECTION, vcpu))
+			kvmi_handle_requests(vcpu);
+
 		if (kvm_vcpu_running(vcpu)) {
 			r = vcpu_enter_guest(vcpu);
 		} else {
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 8509d8272466..296b59ecc540 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -146,6 +146,7 @@ static inline bool is_error_page(struct page *page)
 #define KVM_REQ_MMU_RELOAD        (1 | KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP)
 #define KVM_REQ_PENDING_TIMER     2
 #define KVM_REQ_UNHALT            3
+#define KVM_REQ_INTROSPECTION     4
 #define KVM_REQUEST_ARCH_BASE     8
 
 #define KVM_ARCH_REQ_FLAGS(nr, flags) ({ \
diff --git a/include/linux/kvmi_host.h b/include/linux/kvmi_host.h
index d3242a99f891..956b8d5c51e3 100644
--- a/include/linux/kvmi_host.h
+++ b/include/linux/kvmi_host.h
@@ -53,6 +53,8 @@ int kvmi_ioctl_event(struct kvm *kvm,
 		     const struct kvm_introspection_feature *feat);
 int kvmi_ioctl_preunhook(struct kvm *kvm);
 
+void kvmi_handle_requests(struct kvm_vcpu *vcpu);
+
 #else
 
 static inline int kvmi_init(void) { return 0; }
@@ -61,6 +63,8 @@ static inline void kvmi_create_vm(struct kvm *kvm) { }
 static inline void kvmi_destroy_vm(struct kvm *kvm) { }
 static inline void kvmi_vcpu_uninit(struct kvm_vcpu *vcpu) { }
 
+static inline void kvmi_handle_requests(struct kvm_vcpu *vcpu) { }
+
 #endif /* CONFIG_KVM_INTROSPECTION */
 
 #endif
diff --git a/virt/kvm/introspection/kvmi.c b/virt/kvm/introspection/kvmi.c
index b6595bca99f7..a9d406f276f5 100644
--- a/virt/kvm/introspection/kvmi.c
+++ b/virt/kvm/introspection/kvmi.c
@@ -113,6 +113,12 @@ void kvmi_uninit(void)
 	kvmi_cache_destroy();
 }
 
+static void kvmi_make_request(struct kvm_vcpu *vcpu)
+{
+	kvm_make_request(KVM_REQ_INTROSPECTION, vcpu);
+	kvm_vcpu_kick(vcpu);
+}
+
 static int __kvmi_add_job(struct kvm_vcpu *vcpu,
 			  void (*fct)(struct kvm_vcpu *vcpu, void *ctx),
 			  void *ctx, void (*free_fct)(void *ctx))
@@ -144,6 +150,9 @@ int kvmi_add_job(struct kvm_vcpu *vcpu,
 
 	err = __kvmi_add_job(vcpu, fct, ctx, free_fct);
 
+	if (!err)
+		kvmi_make_request(vcpu);
+
 	return err;
 }
 
@@ -312,6 +321,14 @@ int kvmi_ioctl_unhook(struct kvm *kvm)
 	return 0;
 }
 
+struct kvm_introspection * __must_check kvmi_get(struct kvm *kvm)
+{
+	if (refcount_inc_not_zero(&kvm->kvmi_ref))
+		return kvm->kvmi;
+
+	return NULL;
+}
+
 void kvmi_put(struct kvm *kvm)
 {
 	if (refcount_dec_and_test(&kvm->kvmi_ref))
@@ -373,6 +390,10 @@ int kvmi_hook(struct kvm *kvm, const struct kvm_introspection_hook *hook)
 	init_completion(&kvm->kvmi_complete);
 
 	refcount_set(&kvm->kvmi_ref, 1);
+	/*
+	 * Paired with refcount_inc_not_zero() from kvmi_get().
+	 */
+	smp_wmb();
 
 	kvmi->recv = kthread_run(kvmi_recv_thread, kvmi, "kvmi-recv");
 	if (IS_ERR(kvmi->recv)) {
@@ -672,3 +693,40 @@ int kvmi_cmd_write_physical(struct kvm *kvm, u64 gpa, size_t size,
 
 	return 0;
 }
+
+static struct kvmi_job *kvmi_pull_job(struct kvm_vcpu_introspection *vcpui)
+{
+	struct kvmi_job *job = NULL;
+
+	spin_lock(&vcpui->job_lock);
+	job = list_first_entry_or_null(&vcpui->job_list, typeof(*job), link);
+	if (job)
+		list_del(&job->link);
+	spin_unlock(&vcpui->job_lock);
+
+	return job;
+}
+
+void kvmi_run_jobs(struct kvm_vcpu *vcpu)
+{
+	struct kvm_vcpu_introspection *vcpui = VCPUI(vcpu);
+	struct kvmi_job *job;
+
+	while ((job = kvmi_pull_job(vcpui))) {
+		job->fct(vcpu, job->ctx);
+		kvmi_free_job(job);
+	}
+}
+
+void kvmi_handle_requests(struct kvm_vcpu *vcpu)
+{
+	struct kvm_introspection *kvmi;
+
+	kvmi = kvmi_get(vcpu->kvm);
+	if (!kvmi)
+		return;
+
+	kvmi_run_jobs(vcpu);
+
+	kvmi_put(vcpu->kvm);
+}
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 1f199da03aa4..92d662e7269f 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2710,6 +2710,8 @@ static int kvm_vcpu_check_block(struct kvm_vcpu *vcpu)
 		goto out;
 	if (signal_pending(current))
 		goto out;
+	if (kvm_test_request(KVM_REQ_INTROSPECTION, vcpu))
+		goto out;
 
 	ret = 0;
 out:
