On 3/17/2025 4:37 AM, Mark Rutland wrote:

On Fri, Mar 14, 2025 at 05:19:22PM -0700, Roman Kisel wrote:

[...]

The 'acpi_disabled' variable doesn't exist for !CONFIG_ACPI, so its use
prior to the ifdeffery looks misplaced.

Usual codestyle is to avoid ifdeffery if possible, using IS_ENABLED().
Otherwise, use a stub, e.g.

That looks much better, thanks for the review! Will implement in
the next version.

| #ifdef CONFIG_ACPI
| static bool __init hyperv_detect_via_acpi(void)
| {
| 	if (acpi_disabled)
| 		return false;
| 	
| 	if (acpi_gbl_FADT.header.revision < 6)
| 		return false;
| 	
| 	return strncmp((char *)&acpi_gbl_FADT.hypervisor_id, "MsHyperV", 8) == 0;
| }
| #else
| static inline bool hyperv_detect_via_acpi(void) { return false; }
| #endif

Mark.

quoted

+static bool __init hyperv_detect_via_smccc(void)
+{
+	uuid_t hyperv_uuid = UUID_INIT(
+		0x4d32ba58, 0x4764, 0xcd24,
+		0x75, 0x6c, 0xef, 0x8e,
+		0x24, 0x70, 0x59, 0x16);
+
+	return arm_smccc_hyp_present(&hyperv_uuid);
+}
+
  static int __init hyperv_init(void)
  {
  	struct hv_get_vp_registers_output	result;

@@ -35,13 +70,11 @@ static int __init hyperv_init(void)
  
  	/*
  	 * Allow for a kernel built with CONFIG_HYPERV to be running in
-	 * a non-Hyper-V environment, including on DT instead of ACPI.
+	 * a non-Hyper-V environment.
+	 *
  	 * In such cases, do nothing and return success.
  	 */
-	if (acpi_disabled)
-		return 0;
-
-	if (strncmp((char *)&acpi_gbl_FADT.hypervisor_id, "MsHyperV", 8))
+	if (!hyperv_detect_via_acpi() && !hyperv_detect_via_smccc())
  		return 0;
  
  	/* Setup the guest ID */

-- 
2.43.0

-- 
Thank you,
Roman