[PATCH] arm: Don't remove EL3 exposure for SMC conduit

[Alexander Graf <agraf@csgraf.de>]

When we expose an SMC conduit, we're implicitly telling the guest that
there is EL3 available because it needs to call it. While that EL3 then
is not backed by the emulated CPU, from the guest's EL2 point of view,
it still means there is an EL3 to call into.

This is a problem for VMware ESXi, which validates EL3 availability before
doing SMC calls. With this patch, VMware ESXi works with SMP in TCG.

Reported-by: Andrei Warkentin <andrey.warkentin@gmail.com>
Signed-off-by: Alexander Graf <agraf@csgraf.de>
---
 target/arm/cpu.c | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/target/arm/cpu.c b/target/arm/cpu.c
index a211804fd3..21092c5242 100644
--- a/target/arm/cpu.c
+++ b/target/arm/cpu.c
@@ -1782,11 +1782,21 @@ static void arm_cpu_realizefn(DeviceState *dev, Error **errp)
          */
         unset_feature(env, ARM_FEATURE_EL3);
 
-        /* Disable the security extension feature bits in the processor feature
-         * registers as well. These are id_pfr1[7:4] and id_aa64pfr0[15:12].
-         */
-        cpu->isar.id_pfr1 &= ~0xf0;
-        cpu->isar.id_aa64pfr0 &= ~0xf000;
+        if (cpu->psci_conduit == QEMU_PSCI_CONDUIT_SMC) {
+            /*
+             * We tell the guest to use SMC calls into EL3 for PSCI calls, so
+             * there has to be EL3 available. We merely execute it on the host
+             * in QEMU rather than in actual EL3 inside the guest.
+             */
+        } else {
+            /*
+             * Disable the security extension feature bits in the processor
+             * feature registers as well. These are id_pfr1[7:4] and
+             * id_aa64pfr0[15:12].
+             */
+            cpu->isar.id_pfr1 &= ~0xf0;
+            cpu->isar.id_aa64pfr0 &= ~0xf000;
+        }
     }
 
     if (!cpu->has_el2) {
-- 
2.30.1 (Apple Git-130)