vm: allocated all pcpus to vm0 at the beginning

allocated all pcpus to vm0 to handle possible AP wakeup flow for all cpus,
as we pass org ACPI table to VM0 - that means VM0 can see all CPUs.

SOS(VM0) start expected CPUs through "maxcpus=" kernel cmdline option.

During first hypercall from SOS, calling vm_fixup to free un-expect-enabled
vcpus from VM0.

Signed-off-by: Jason Chen CJ <jason.cj.chen@intel.com>
Acked-by: Xu, Anthony <anthony.xu@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>

Author: JasonChenCJ

hypervisor/arch/x86/guest/vm.c

@@ -56,7 +56,14 @@ static void init_vm(struct vm_description *vm_desc,
 		struct vm *vm_handle)
 {
 	/* Populate VM attributes from VM description */
-	vm_handle->hw.num_vcpus = vm_desc->vm_hw_num_cores;
+	if (is_vm0(vm_handle)) {
+		/* Allocate all cpus to vm0 at the beginning */
+		vm_handle->hw.num_vcpus = phy_cpu_num;
+		vm_handle->hw.exp_num_vcpus = vm_desc->vm_hw_num_cores;
+	} else {
+		vm_handle->hw.num_vcpus = vm_desc->vm_hw_num_cores;
+		vm_handle->hw.exp_num_vcpus = vm_desc->vm_hw_num_cores;
+	}
 	vm_handle->state_info.privilege = vm_desc->vm_state_info_privilege;
 	vm_handle->state_info.boot_count = 0;
 }
@@ -316,11 +323,9 @@ int prepare_vm0(void)
 	ret = create_vm(vm_desc, &vm);
 	ASSERT(ret == 0, "VM creation failed!");
 
-	prepare_vcpu(vm, vm_desc->vm_hw_logical_core_ids[0]);
-
-	/* Prepare the AP for vm0 */
-	for (i = 1; i < vm_desc->vm_hw_num_cores; i++)
-		prepare_vcpu(vm, vm_desc->vm_hw_logical_core_ids[i]);
+	/* Allocate all cpus to vm0 at the beginning */
+	for (i = 0; i < phy_cpu_num; i++)
+		prepare_vcpu(vm, i);
 
 	/* start vm0 BSP automatically */
 	start_vm(vm);
@@ -329,3 +334,48 @@ int prepare_vm0(void)
 
 	return 0;
 }
+
+static inline bool vcpu_in_vm_desc(struct vcpu *vcpu,
+		struct vm_description *vm_desc)
+{
+	int i;
+
+	for (i = 0; i < vm_desc->vm_hw_num_cores; i++) {
+		if (vcpu->pcpu_id == vm_desc->vm_hw_logical_core_ids[i])
+			return true;
+	}
+
+	return false;
+}
+
+/*
+ * fixup vm0 for expected vcpu:
+ *  vm0 is starting with all physical cpus, it's mainly for UEFI boot to
+ *  handle all physical mapped APs wakeup during boot service exit.
+ *  this fixup is used to pause then destroy non-expect-enabled vcpus from VM0.
+ *
+ * NOTE: if you want to enable mult-vpucs for vm0, please make sure the pcpu_id
+ *       is in order, for example:
+ *       - one vcpu:    VM0_CPUS[VM0_NUM_CPUS] = {0};
+ *       - two vcpus:   VM0_CPUS[VM0_NUM_CPUS] = {0, 1};
+ *       - three vcpus: VM0_CPUS[VM0_NUM_CPUS] = {0, 1, 2};
+ */
+void vm_fixup(struct vm *vm)
+{
+	if (is_vm0(vm) && (vm->hw.exp_num_vcpus < vm->hw.num_vcpus)) {
+		struct vm_description *vm_desc = NULL;
+		struct vcpu *vcpu;
+		int i;
+
+		vm_desc = get_vm_desc(0);
+		foreach_vcpu(i, vm, vcpu) {
+			if (!vcpu_in_vm_desc(vcpu, vm_desc)) {
+				pause_vcpu(vcpu, VCPU_ZOMBIE);
+				reset_vcpu(vcpu);
+				destroy_vcpu(vcpu);
+			}
+		}
+
+		vm->hw.num_vcpus = vm->hw.exp_num_vcpus;
+	}
+}

hypervisor/arch/x86/guest/vmcall.c

@@ -55,6 +55,10 @@ int vmcall_vmexit_handler(struct vcpu *vcpu)
 	/* Dispatch the hypercall handler */
 	switch (hypcall_id) {
 	case HC_GET_API_VERSION:
+		/* vm0 will call HC_GET_API_VERSION as first hypercall, fixup
+		 * vm0 vcpu here.
+		 */
+		vm_fixup(vm);
 		ret = hcall_get_api_version(vm, param1);
 		break;
 

hypervisor/include/arch/x86/guest/vm.h

@@ -46,6 +46,7 @@ struct vm_attr {
 
 struct vm_hw_info {
 	int num_vcpus;	/* Number of total virtual cores */
+	int exp_num_vcpus;	/* Number of real expected virtual cores */
 	uint32_t created_vcpus;	/* Number of created vcpus */
 	struct vcpu **vcpu_array;	/* vcpu array of this VM */
 	uint64_t gpa_lowtop;    /* top lowmem gpa of this VM */
@@ -218,6 +219,7 @@ int pause_vm(struct vm *vm);
 int start_vm(struct vm *vm);
 int create_vm(struct vm_description *vm_desc, struct vm **vm);
 int prepare_vm0(void);
+void vm_fixup(struct vm *vm);
 
 struct vm *get_vm_from_vmid(int vm_id);
 struct vm_description *get_vm_desc(int idx);