From: Mihai Donțu <[email protected]>

The introspection requests (KVM_REQ_INTROSPECTION) are checked before
entering guest or when the vCPU is halted.

Signed-off-by: Mihai Donțu <[email protected]>
Co-developed-by: Mircea Cîrjaliu <[email protected]>
Signed-off-by: Mircea Cîrjaliu <[email protected]>
Co-developed-by: Adalbert Lazăr <[email protected]>
Signed-off-by: Adalbert Lazăr <[email protected]>
---
 arch/x86/include/asm/kvm_host.h |  1 +
 arch/x86/kvm/x86.c              |  3 ++
 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/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 6169e12d2540..c2176012676d 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -80,6 +80,7 @@
 #define KVM_REQ_GET_VMCS12_PAGES       KVM_ARCH_REQ(24)
 #define KVM_REQ_APICV_UPDATE \
        KVM_ARCH_REQ_FLAGS(25, KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP)
+#define KVM_REQ_INTROSPECTION          KVM_ARCH_REQ(26)
 
 #define CR0_RESERVED_BITS                                               \
        (~(unsigned long)(X86_CR0_PE | X86_CR0_MP | X86_CR0_EM | X86_CR0_TS \
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 4fa11c998325..967c83791b37 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8549,6 +8549,9 @@ 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/kvmi_host.h b/include/linux/kvmi_host.h
index 1d80d233fbd5..6a0fb481b192 100644
--- a/include/linux/kvmi_host.h
+++ b/include/linux/kvmi_host.h
@@ -56,6 +56,8 @@ int kvmi_ioctl_command(struct kvm *kvm, void __user *argp);
 int kvmi_ioctl_event(struct kvm *kvm, void __user *argp);
 int kvmi_ioctl_preunhook(struct kvm *kvm);
 
+void kvmi_handle_requests(struct kvm_vcpu *vcpu);
+
 #else
 
 static inline int kvmi_init(void) { return 0; }
@@ -64,6 +66,8 @@ 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 e36460b755e9..65a77b8d2616 100644
--- a/virt/kvm/introspection/kvmi.c
+++ b/virt/kvm/introspection/kvmi.c
@@ -87,6 +87,12 @@ 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))
@@ -118,6 +124,9 @@ 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;
 }
 
@@ -270,6 +279,14 @@ 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))
@@ -331,6 +348,10 @@ 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)) {
@@ -635,3 +656,40 @@ 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 8d2a4a1ae3b0..5f2031234636 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2484,6 +2484,8 @@ 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:
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