KVM: TDX: Implement TDX vcpu enter/exit path

This patch implements running TDX vcpu.  Once vcpu runs on the logical
processor (LP), the TDX vcpu is associated with it.  When the TDX vcpu
moves to another LP, the TDX vcpu needs to flush its status on the LP.
When destroying TDX vcpu, it needs to complete flush and flush cpu memory
cache.  Track which LP the TDX vcpu run and flush it as necessary.

Do nothing on sched_in event as TDX doesn't support pause loop.

Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>

arch/x86/kvm/vmx/main.c

@@ -94,6 +94,14 @@ static int vt_vcpu_create(struct kvm_vcpu *vcpu)
 	return vmx_create_vcpu(vcpu);
 }
 
+static fastpath_t vt_vcpu_run(struct kvm_vcpu *vcpu)
+{
+	if (is_td_vcpu(vcpu))
+		return tdx_vcpu_run(vcpu);
+
+	return vmx_vcpu_run(vcpu);
+}
+
 static void vt_vcpu_free(struct kvm_vcpu *vcpu)
 {
 	if (is_td_vcpu(vcpu))
@@ -110,6 +118,38 @@ static void vt_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
 	return vmx_vcpu_reset(vcpu, init_event);
 }
 
+static void vt_prepare_switch_to_guest(struct kvm_vcpu *vcpu)
+{
+	/*
+	 * All host state is saved/restored across SEAMCALL/SEAMRET, and the
+	 * guest state of a TD is obviously off limits.	 Deferring MSRs and DRs
+	 * is pointless because TDX-SEAM needs to load *something* so as not to
+	 * expose guest state.
+	 */
+	if (is_td_vcpu(vcpu)) {
+		tdx_prepare_switch_to_guest(vcpu);
+		return;
+	}
+
+	vmx_prepare_switch_to_guest(vcpu);
+}
+
+static void vt_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
+{
+	if (is_td_vcpu(vcpu))
+		return tdx_vcpu_load(vcpu, cpu);
+
+	return vmx_vcpu_load(vcpu, cpu);
+}
+
+static void vt_vcpu_put(struct kvm_vcpu *vcpu)
+{
+	if (is_td_vcpu(vcpu))
+		return tdx_vcpu_put(vcpu);
+
+	return vmx_vcpu_put(vcpu);
+}
+
 static void vt_flush_tlb_all(struct kvm_vcpu *vcpu)
 {
 	if (is_td_vcpu(vcpu))
@@ -151,6 +191,14 @@ static void vt_load_mmu_pgd(struct kvm_vcpu *vcpu, hpa_t root_hpa,
 	vmx_load_mmu_pgd(vcpu, root_hpa, pgd_level);
 }
 
+static void vt_sched_in(struct kvm_vcpu *vcpu, int cpu)
+{
+	if (is_td_vcpu(vcpu))
+		return;
+
+	vmx_sched_in(vcpu, cpu);
+}
+
 static int vt_mem_enc_op_dev(void __user *argp)
 {
 	if (!enable_tdx)
@@ -195,9 +243,9 @@ struct kvm_x86_ops vt_x86_ops __initdata = {
 	.vcpu_free = vt_vcpu_free,
 	.vcpu_reset = vt_vcpu_reset,
 
-	.prepare_guest_switch = vmx_prepare_switch_to_guest,
-	.vcpu_load = vmx_vcpu_load,
-	.vcpu_put = vmx_vcpu_put,
+	.prepare_guest_switch = vt_prepare_switch_to_guest,
+	.vcpu_load = vt_vcpu_load,
+	.vcpu_put = vt_vcpu_put,
 
 	.update_exception_bitmap = vmx_update_exception_bitmap,
 	.get_msr_feature = vmx_get_msr_feature,
@@ -227,7 +275,7 @@ struct kvm_x86_ops vt_x86_ops __initdata = {
 	.tlb_flush_gva = vt_flush_tlb_gva,
 	.tlb_flush_guest = vt_flush_tlb_guest,
 
-	.run = vmx_vcpu_run,
+	.run = vt_vcpu_run,
 	.handle_exit = vmx_handle_exit,
 	.skip_emulated_instruction = vmx_skip_emulated_instruction,
 	.update_emulated_instruction = vmx_update_emulated_instruction,
@@ -280,7 +328,7 @@ struct kvm_x86_ops vt_x86_ops __initdata = {
 
 	.request_immediate_exit = vmx_request_immediate_exit,
 
-	.sched_in = vmx_sched_in,
+	.sched_in = vt_sched_in,
 
 	.cpu_dirty_log_size = PML_ENTITY_NUM,
 	.update_cpu_dirty_logging = vmx_update_cpu_dirty_logging,