hv: don't overwrite the statically configured vm_configs[] in hypercall

The statically configured vm_configs[].cpu_affinity_bitmap should remain
intact during the life cycle of the SOS, otherwise user can't destroy
and create the same VM with different CPU affinity. For example:

- Initially vm_configs[1].cpu_affinity_bitmap is set to 0xF: pCPU 0/1/2/3.
- VM1 is created on pCPU1 and pCPU2 and vm_configs[1].cpu_affinity_bitmap
  is overwritten as 0x6.
- VM1 is destroyed.
- Now VM1 can't be launched again on pCPU0 or pCPU3.

This patch fixes this by saving the static VM configuration before the
create_vm hypercall and restore it when the post-launched VM is shutting
down.

Tracked-On: #4616
Signed-off-by: Zide Chen <zide.chen@intel.com>

hypervisor/arch/x86/configs/vm_config.c

@@ -14,6 +14,15 @@
 static uint8_t rtvm_uuid1[16] = POST_RTVM_UUID1;
 static uint8_t safety_vm_uuid1[16] = SAFETY_VM_UUID1;
 
+/*
+ * To be used for post-launched VMS only.
+ *
+ * acrn-dm could modify post-launched VM configuration through command line arguments.
+ * We make use of this additional array to make sure that the dynamic configuration
+ * from acrn-dm won't overwrite the static vm_configs[].
+ */
+static struct acrn_vm_config vm_configs_saved[CONFIG_MAX_VM_NUM];
+
 /*
  * @pre vm_id < CONFIG_MAX_VM_NUM
  * @post return != NULL
@@ -23,6 +32,20 @@ struct acrn_vm_config *get_vm_config(uint16_t vm_id)
 	return &vm_configs[vm_id];
 }
 
+/*
+ * @pre vm_id < CONFIG_MAX_VM_NUM
+ */
+void save_or_restore_vm_config(uint16_t vm_id, bool save)
+{
+	size_t size = sizeof(struct acrn_vm_config);
+
+	if (save) {
+		(void)memcpy_s((void *)&vm_configs_saved[vm_id], size, (void *)&vm_configs[vm_id], size);
+	} else {
+		(void)memcpy_s((void *)&vm_configs[vm_id], size, (void *)&vm_configs_saved[vm_id], size);
+	}
+}
+
 static inline bool uuid_is_equal(const uint8_t *uuid1, const uint8_t *uuid2)
 {
 	uint64_t uuid1_h = *(const uint64_t *)uuid1;

hypervisor/arch/x86/guest/vm.c

@@ -585,7 +585,6 @@ int32_t shutdown_vm(struct acrn_vm *vm)
 	uint16_t i;
 	uint64_t mask;
 	struct acrn_vcpu *vcpu = NULL;
-	struct acrn_vm_config *vm_config = NULL;
 	int32_t ret = 0;
 
 	pause_vm(vm);
@@ -603,9 +602,6 @@ int32_t shutdown_vm(struct acrn_vm *vm)
 			offline_vcpu(vcpu);
 		}
 
-		vm_config = get_vm_config(vm->vm_id);
-		vm_config->guest_flags &= ~DM_OWNED_GUEST_FLAG_MASK;
-
 		if (is_sos_vm(vm)) {
 			sbuf_reset();
 		}

hypervisor/common/hypercall.c

@@ -161,6 +161,9 @@ int32_t hcall_create_vm(struct acrn_vm *vm, uint64_t param)
 		vm_id = get_vmid_by_uuid(&cv.uuid[0]);
 		if ((vm_id > vm->vm_id) && (vm_id < CONFIG_MAX_VM_NUM)
 			&& (is_poweroff_vm(get_vm_from_vmid(vm_id)))) {
+
+			/* Save a copy of the static vm configuration */
+			save_or_restore_vm_config(vm_id, true);
 			vm_config = get_vm_config(vm_id);
 
 			/* Filter out the bits should not set by DM and then assign it to guest_flags */
@@ -220,6 +223,9 @@ int32_t hcall_destroy_vm(uint16_t vmid)
 	if (!is_poweroff_vm(target_vm) && is_postlaunched_vm(target_vm)) {
 		/* TODO: check target_vm guest_flags */
 		ret = shutdown_vm(target_vm);
+
+		/* restore with the static vm configuration */
+		save_or_restore_vm_config(vmid, false);
 	}
 
 	return ret;

hypervisor/include/arch/x86/vm_config.h

@@ -175,6 +175,7 @@ struct acrn_vm_config {
 } __aligned(8);
 
 struct acrn_vm_config *get_vm_config(uint16_t vm_id);
+void save_or_restore_vm_config(uint16_t vm_id, bool save);
 bool vm_has_matched_uuid(uint16_t vmid, const uint8_t *uuid);
 bool sanitize_vm_config(void);