[PATCH v2 1/6] arm64/hyperv: Support DeviceTree

Roman Kisel
2024-05-14T22:45:27Z

The Virtual Trust Level platforms rely on DeviceTree, and the
arm64/hyperv code supports ACPI only. Update the logic to
support DeviceTree on boot as well as ACPI.

Signed-off-by: Roman Kisel <romank@linux.microsoft.com>
---
arch/arm64/hyperv/mshyperv.c | 34 +++++++++++++++++++++++++++++-----
1 file changed, 29 insertions(+), 5 deletions(-)

diff --git a/arch/arm64/hyperv/mshyperv.c b/arch/arm64/hyperv/mshyperv.c
index b1a4de4eee29..208a3bcb9686 100644
--- a/arch/arm64/hyperv/mshyperv.c
+++ b/arch/arm64/hyperv/mshyperv.c
@@ -15,6 +15,9 @@
#include <linux/errno.h>
#include <linux/version.h>
#include <linux/cpuhotplug.h>
+#include <linux/libfdt.h>
+#include <linux/of.h>
+#include <linux/of_fdt.h>
#include <asm/mshyperv.h>

static bool hyperv_initialized;
@@ -27,6 +30,29 @@ int hv_get_hypervisor_version(union hv_hypervisor_version_info *info)
return 0;
}

+static bool hyperv_detect_fdt(void)
+{
+#ifdef CONFIG_OF
+ const unsigned long hyp_node = of_get_flat_dt_subnode_by_name(
+ of_get_flat_dt_root(), "hypervisor");
+
+ return (hyp_node != -FDT_ERR_NOTFOUND) &&
+ of_flat_dt_is_compatible(hyp_node, "microsoft,hyperv");
+#else
+ return false;
+#endif
+}
+
+static bool hyperv_detect_acpi(void)
+{
+#ifdef CONFIG_ACPI
+ return !acpi_disabled &&
+ !strncmp((char *)&acpi_gbl_FADT.hypervisor_id, "MsHyperV", 8);
+#else
+ return false;
+#endif
+}
+
static int __init hyperv_init(void)
{
struct hv_get_vp_registers_output result;
@@ -35,13 +61,11 @@ 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_fdt() && !hyperv_detect_acpi())
return 0;

/* Setup the guest ID */
--
2.45.0