hyperv: Move hv_current_partition_id to arch-generic code

Move hv_current_partition_id and hv_get_partition_id() to hv_common.c,
and call hv_get_partition_id() on arm64 in hyperv_init(). These aren't
specific to x86_64 and will be needed by common code.

Set hv_current_partition_id to HV_PARTITION_ID_SELF by default.

Rename struct hv_get_partition_id to hv_output_get_partition_id, to
make it distinct from the function hv_get_partition_id(), and match
the original Hyper-V struct name.

Remove the BUG()s. Failing to get the id need not crash the machine.

Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
Reviewed-by: Michael Kelley <mhklinux@outlook.com>
Link: https://lore.kernel.org/r/1738955002-20821-2-git-send-email-nunodasneves@linux.microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Message-ID: <1738955002-20821-2-git-send-email-nunodasneves@linux.microsoft.com>

Author: NunoDasNeves

arch/arm64/hyperv/mshyperv.c

@@ -72,6 +72,9 @@ static int __init hyperv_init(void)
 		return ret;
 	}
 
+	if (ms_hyperv.priv_high & HV_ACCESS_PARTITION_ID)
+		hv_get_partition_id();
+
 	ms_hyperv_late_init();
 
 	hyperv_initialized = true;

arch/x86/hyperv/hv_init.c

@@ -34,9 +34,6 @@
 #include <clocksource/hyperv_timer.h>
 #include <linux/highmem.h>
 
-u64 hv_current_partition_id = ~0ull;
-EXPORT_SYMBOL_GPL(hv_current_partition_id);
-
 void *hv_hypercall_pg;
 EXPORT_SYMBOL_GPL(hv_hypercall_pg);
 
@@ -393,24 +390,6 @@ static void __init hv_stimer_setup_percpu_clockev(void)
 		old_setup_percpu_clockev();
 }
 
-static void __init hv_get_partition_id(void)
-{
-	struct hv_get_partition_id *output_page;
-	u64 status;
-	unsigned long flags;
-
-	local_irq_save(flags);
-	output_page = *this_cpu_ptr(hyperv_pcpu_output_arg);
-	status = hv_do_hypercall(HVCALL_GET_PARTITION_ID, NULL, output_page);
-	if (!hv_result_success(status)) {
-		/* No point in proceeding if this failed */
-		pr_err("Failed to get partition ID: %lld\n", status);
-		BUG();
-	}
-	hv_current_partition_id = output_page->partition_id;
-	local_irq_restore(flags);
-}
-
 #if IS_ENABLED(CONFIG_HYPERV_VTL_MODE)
 static u8 __init get_vtl(void)
 {
@@ -605,11 +584,9 @@ void __init hyperv_init(void)
 
 	register_syscore_ops(&hv_syscore_ops);
 
-	if (cpuid_ebx(HYPERV_CPUID_FEATURES) & HV_ACCESS_PARTITION_ID)
+	if (ms_hyperv.priv_high & HV_ACCESS_PARTITION_ID)
 		hv_get_partition_id();
 
-	BUG_ON(hv_root_partition && hv_current_partition_id == ~0ull);
-
 #ifdef CONFIG_PCI_MSI
 	/*
 	 * If we're running as root, we want to create our own PCI MSI domain.

arch/x86/include/asm/mshyperv.h

@@ -43,8 +43,6 @@ extern bool hyperv_paravisor_present;
 
 extern void *hv_hypercall_pg;
 
-extern u64 hv_current_partition_id;
-
 extern union hv_ghcb * __percpu *hv_ghcb_pg;
 
 bool hv_isolation_type_snp(void);

drivers/hv/hv_common.c

@@ -31,6 +31,9 @@
 #include <hyperv/hvhdk.h>
 #include <asm/mshyperv.h>
 
+u64 hv_current_partition_id = HV_PARTITION_ID_SELF;
+EXPORT_SYMBOL_GPL(hv_current_partition_id);
+
 /*
  * hv_root_partition, ms_hyperv and hv_nested are defined here with other
  * Hyper-V specific globals so they are shared across all architectures and are
@@ -283,6 +286,25 @@ static inline bool hv_output_page_exists(void)
 	return hv_root_partition || IS_ENABLED(CONFIG_HYPERV_VTL_MODE);
 }
 
+void __init hv_get_partition_id(void)
+{
+	struct hv_output_get_partition_id *output;
+	unsigned long flags;
+	u64 status, pt_id;
+
+	local_irq_save(flags);
+	output = *this_cpu_ptr(hyperv_pcpu_input_arg);
+	status = hv_do_hypercall(HVCALL_GET_PARTITION_ID, NULL, &output);
+	pt_id = output->partition_id;
+	local_irq_restore(flags);
+
+	if (hv_result_success(status))
+		hv_current_partition_id = pt_id;
+	else
+		pr_err("Hyper-V: failed to get partition ID: %#x\n",
+		       hv_result(status));
+}
+
 int __init hv_common_init(void)
 {
 	int i;

include/asm-generic/mshyperv.h

@@ -58,6 +58,7 @@ struct ms_hyperv_info {
 };
 extern struct ms_hyperv_info ms_hyperv;
 extern bool hv_nested;
+extern u64 hv_current_partition_id;
 
 extern void * __percpu *hyperv_pcpu_input_arg;
 extern void * __percpu *hyperv_pcpu_output_arg;
@@ -207,6 +208,7 @@ extern u64 (*hv_read_reference_counter)(void);
 #define VP_INVAL	U32_MAX
 
 int __init hv_common_init(void);
+void __init hv_get_partition_id(void);
 void __init hv_common_free(void);
 void __init ms_hyperv_late_init(void);
 int hv_common_cpu_init(unsigned int cpu);

include/hyperv/hvgdk_mini.h

@@ -182,7 +182,7 @@ struct hv_tsc_emulation_control {	 /* HV_TSC_INVARIANT_CONTROL */
 
 #endif /* CONFIG_X86 */
 
-struct hv_get_partition_id {	 /* HV_OUTPUT_GET_PARTITION_ID */
+struct hv_output_get_partition_id {
 	u64 partition_id;
 } __packed;