mshv: Add support for a new parent partition configuration

Detect booting as an "L1VH" partition. This is a new scenario very
similar to root partition where the mshv_root driver can be used to
create and manage guest partitions.

It mostly works the same as root partition, but there are some
differences in how various features are handled. hv_l1vh_partition()
is introduced to handle these cases. Add hv_parent_partition()
which returns true for either case, replacing some hv_root_partition()
checks.

Signed-off-by: Nuno Das Neves <[e-mail]>
Acked-by: Wei Liu <[e-mail]>
Reviewed-by: Michael Kelley <[e-mail]>
Signed-off-by: Wei Liu <[e-mail]>

drivers/hv/hv_common.c

···
 
 static inline bool hv_output_page_exists(void)
 {
-	return hv_root_partition() || IS_ENABLED(CONFIG_HYPERV_VTL_MODE);
+	return hv_parent_partition() || IS_ENABLED(CONFIG_HYPERV_VTL_MODE);
 }
 
 void __init hv_get_partition_id(void)
···
 		BUG_ON(!hyperv_pcpu_output_arg);
 	}
 
-	if (hv_root_partition()) {
+	if (hv_parent_partition()) {
 		hv_synic_eventring_tail = alloc_percpu(u8 *);
 		BUG_ON(!hv_synic_eventring_tail);
 	}
···
 	if (msr_vp_index > hv_max_vp_index)
 		hv_max_vp_index = msr_vp_index;
 
-	if (hv_root_partition()) {
+	if (hv_parent_partition()) {
 		synic_eventring_tail = (u8 **)this_cpu_ptr(hv_synic_eventring_tail);
 		*synic_eventring_tail = kcalloc(HV_SYNIC_SINT_COUNT,
 						sizeof(u8), flags);
···
 	 * originally allocated memory is reused in hv_common_cpu_init().
 	 */
 
-	if (hv_root_partition()) {
+	if (hv_parent_partition()) {
 		synic_eventring_tail = this_cpu_ptr(hv_synic_eventring_tail);
 		kfree(*synic_eventring_tail);
 		*synic_eventring_tail = NULL;
···
 	 * the root partition setting if also a Confidential VM.
 	 */
 	if ((ms_hyperv.priv_high & HV_CREATE_PARTITIONS) &&
-	    (ms_hyperv.priv_high & HV_CPU_MANAGEMENT) &&
 	    !(ms_hyperv.priv_high & HV_ISOLATION)) {
-		pr_info("Hyper-V: running as root partition\n");
-		if (IS_ENABLED(CONFIG_MSHV_ROOT))
-			hv_curr_partition_type = HV_PARTITION_TYPE_ROOT;
-		else
+
+		if (!IS_ENABLED(CONFIG_MSHV_ROOT)) {
 			pr_crit("Hyper-V: CONFIG_MSHV_ROOT not enabled!\n");
+		} else if (ms_hyperv.priv_high & HV_CPU_MANAGEMENT) {
+			pr_info("Hyper-V: running as root partition\n");
+			hv_curr_partition_type = HV_PARTITION_TYPE_ROOT;
+		} else {
+			pr_info("Hyper-V: running as L1VH partition\n");
+			hv_curr_partition_type = HV_PARTITION_TYPE_L1VH;
+		}
 	}
 }
 

drivers/hv/mshv_root_main.c

···
 MODULE_LICENSE("GPL");
 MODULE_DESCRIPTION("Microsoft Hyper-V root partition VMM interface /dev/mshv");
 
-/* TODO move this to mshyperv.h when needed outside driver */
-static inline bool hv_parent_partition(void)
-{
-	return hv_root_partition();
-}
-
 /* TODO move this to another file when debugfs code is added */
 enum hv_stats_vp_counters {			/* HV_THREAD_COUNTER */
 #if defined(CONFIG_X86)
···
 /* Retrieve and stash the supported scheduler type */
 static int __init mshv_retrieve_scheduler_type(struct device *dev)
 {
-	int ret;
+	int ret = 0;
 
-	ret = hv_retrieve_scheduler_type(&hv_scheduler_type);
+	if (hv_l1vh_partition())
+		hv_scheduler_type = HV_SCHEDULER_TYPE_CORE_SMT;
+	else
+		ret = hv_retrieve_scheduler_type(&hv_scheduler_type);
+
 	if (ret)
 		return ret;
 
···
 {
 	int err;
 
-	if (mshv_retrieve_scheduler_type(dev))
-		return -ENODEV;
-
 	err = root_scheduler_init(dev);
 	if (err)
 		return err;
···
 	struct device *dev;
 	union hv_hypervisor_version_info version_info;
 
-	if (!hv_root_partition() || is_kdump_kernel())
+	if (!hv_parent_partition() || is_kdump_kernel())
 		return -ENODEV;
 
 	if (hv_get_hypervisor_version(&version_info))
···
 
 	mshv_cpuhp_online = ret;
 
-	ret = mshv_root_partition_init(dev);
+	ret = mshv_retrieve_scheduler_type(dev);
+	if (ret)
+		goto remove_cpu_state;
+
+	if (hv_root_partition())
+		ret = mshv_root_partition_init(dev);
 	if (ret)
 		goto remove_cpu_state;
 

include/asm-generic/mshyperv.h

···
 enum hv_partition_type {
 	HV_PARTITION_TYPE_GUEST,
 	HV_PARTITION_TYPE_ROOT,
+	HV_PARTITION_TYPE_L1VH,
 };
 
 struct ms_hyperv_info {
···
 {
 	return hv_curr_partition_type == HV_PARTITION_TYPE_ROOT;
 }
+static inline bool hv_l1vh_partition(void)
+{
+	return hv_curr_partition_type == HV_PARTITION_TYPE_L1VH;
+}
+static inline bool hv_parent_partition(void)
+{
+	return hv_root_partition() || hv_l1vh_partition();
+}
 int hv_call_deposit_pages(int node, u64 partition_id, u32 num_pages);
 int hv_call_add_logical_proc(int node, u32 lp_index, u32 acpi_id);
 int hv_call_create_vp(int node, u64 partition_id, u32 vp_index, u32 flags);
 
 #else /* CONFIG_MSHV_ROOT */
 static inline bool hv_root_partition(void) { return false; }
+static inline bool hv_l1vh_partition(void) { return false; }
+static inline bool hv_parent_partition(void) { return false; }
 static inline int hv_call_deposit_pages(int node, u64 partition_id, u32 num_pages)
 {
 	return -EOPNOTSUPP;