On 5/16/2024 8:27 AM, Roman Kisel wrote:

On 5/15/2024 3:02 PM, Elliot Berman wrote:

quoted

On Tue, May 14, 2024 at 03:43:48PM -0700, Roman Kisel wrote:

quoted

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.

Could you use Call UID query from SMCCC? KVM [1] and Gunyah [2] have
been using this to identify if guest is running under those respective
hypervisors. This works in both DT and ACPI cases.

[1]: https://lore.kernel.org/all/20210330145430.996981-2-maz@kernel.org/ (local)
[2]: 
https://lore.kernel.org/all/20240222-gunyah-v17-4-1e9da6763d38@quicinc.com/ (local)

That would be very neat indeed, thanks! Talking to the hypervisor folks.

We have that now. Will send out the revised patches sometime during the 
next week most likely.

quoted

quoted

Signed-off-by: Roman Kisel <redacted>
---
  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


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-- 
Thank you,
Roman