[RFC] virt/acpi: set PSCI flag even when psci_conduit is disabled

[Heyi Guo <guoheyi@linux.alibaba.com>]

vms->psci_conduit being disabled only means PSCI is not implemented by
qemu; it doesn't mean PSCI is not supported on this virtual machine.
Actually vms->psci_conduit is set to disabled when vms->secure and
firmware_loaded are both set, which means we will run ARM trusted
firmware, which will definitely provide PSCI.

The issue can be reproduced when running qemu in TCG mode with secure
enabled, while using ARM trusted firmware + qemu virt UEFI as firmware
binaries, and we can see secondary cores will not be waken up.

Signed-off-by: Heyi Guo <guoheyi@linux.alibaba.com>

---
Cc: Shannon Zhao <shannon.zhaosl@gmail.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Peter Maydell <peter.maydell@linaro.org>
Cc: qemu-arm@nongnu.org
---
 hw/arm/virt-acpi-build.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c
index 1384a2c..7622b97 100644
--- a/hw/arm/virt-acpi-build.c
+++ b/hw/arm/virt-acpi-build.c
@@ -728,13 +728,16 @@ static void build_fadt_rev5(GArray *table_data, BIOSLinker *linker,
     };
 
     switch (vms->psci_conduit) {
-    case QEMU_PSCI_CONDUIT_DISABLED:
-        fadt.arm_boot_arch = 0;
-        break;
     case QEMU_PSCI_CONDUIT_HVC:
         fadt.arm_boot_arch = ACPI_FADT_ARM_PSCI_COMPLIANT |
                              ACPI_FADT_ARM_PSCI_USE_HVC;
         break;
+    /*
+     * QEMU_PSCI_CONDUIT_DISABLED only means PSCI is not implemented by qemu,
+     * but typically it will still be provided by secure firmware, and it should
+     * use SMC as PSCI conduit.
+     */
+    case QEMU_PSCI_CONDUIT_DISABLED:
     case QEMU_PSCI_CONDUIT_SMC:
         fadt.arm_boot_arch = ACPI_FADT_ARM_PSCI_COMPLIANT;
         break;
-- 
2.7.4