When it's a Xen domain0 booting with ACPI, it will supply a /chosen and
a /hypervisor node in DT. So check if it needs to enable ACPI.

Signed-off-by: Shannon Zhao <redacted>
Reviewed-by: Stefano Stabellini <redacted>
Acked-by: Hanjun Guo <redacted>
---
 arch/arm64/kernel/acpi.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
index d1ce8e2..4e92be0 100644
--- a/arch/arm64/kernel/acpi.c
+++ b/arch/arm64/kernel/acpi.c

@@ -67,10 +67,13 @@ static int __init dt_scan_depth1_nodes(unsigned long node,
 {
 	/*
 	 * Return 1 as soon as we encounter a node at depth 1 that is
-	 * not the /chosen node.
+	 * not the /chosen node, or /hypervisor node when running on Xen.
 	 */
-	if (depth == 1 && (strcmp(uname, "chosen") != 0))
-		return 1;
+	if (depth == 1 && (strcmp(uname, "chosen") != 0)) {
+		if (!xen_initial_domain() || (strcmp(uname, "hypervisor") != 0))
+			return 1;
+	}
+
 	return 0;
 }
 

@@ -184,7 +187,8 @@ void __init acpi_boot_table_init(void)
 	/*
 	 * Enable ACPI instead of device tree unless
 	 * - ACPI has been disabled explicitly (acpi=off), or
-	 * - the device tree is not empty (it has more than just a /chosen node)
+	 * - the device tree is not empty (it has more than just a /chosen node,
+	 *   and a /hypervisor node when running on Xen)
 	 *   and ACPI has not been force enabled (acpi=force)
 	 */
 	if (param_acpi_off ||

-- 
2.1.4