[kvm-unit-tests RFC PATCH v3 6/7] arm64: selftest: Expand EL2 test to disable and re-enable VHE

[Alexandru Elisei <alexandru.elisei@arm.com>]

Check that disabling VHE, then re-enabling it again, works.

Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
---

Disabling VHE is broken with version v1 of the NV patches; to run the tests
I use this patch:

--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -333,7 +333,8 @@ void vcpu_write_sys_reg(struct kvm_vcpu *vcpu, u64 val, int reg)
                 * to reverse-translate virtual EL2 system registers for a
                 * non-VHE guest hypervisor.
                 */
-               __vcpu_sys_reg(vcpu, reg) = val;
+               if (reg != HCR_EL2)
+                       __vcpu_sys_reg(vcpu, reg) = val;
 
                switch (reg) {
                case ELR_EL2:
@@ -370,7 +371,17 @@ void vcpu_write_sys_reg(struct kvm_vcpu *vcpu, u64 val, int reg)
                return;
 
 memory_write:
-        __vcpu_sys_reg(vcpu, reg) = val;
+       if (reg == HCR_EL2 && vcpu_el2_e2h_is_set(vcpu) && !(val & HCR_E2H)) {
+               preempt_disable();
+               kvm_arch_vcpu_put(vcpu);
+
+               __vcpu_sys_reg(vcpu, reg) = val;
+
+               kvm_arch_vcpu_load(vcpu, smp_processor_id());
+               preempt_enable();
+       } else {
+                __vcpu_sys_reg(vcpu, reg) = val;
+       }
 }
 
 /* 3 bits per cache level, as per CLIDR, but non-existent caches always 0 */

 arm/selftest.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arm/selftest.c b/arm/selftest.c
index a30e101a4920..b7f2a83be65f 100644
--- a/arm/selftest.c
+++ b/arm/selftest.c
@@ -424,6 +424,14 @@ static void check_el2_cpu(void *data __unused)
 	report(current_level() == CurrentEL_EL2, "CPU(%3d) Running at EL2", cpu);
 	report(vhe_supported() && vhe_enabled(),
 			"CPU(%3d) VHE supported and enabled", cpu);
+
+	disable_vhe();
+	report(current_level() == CurrentEL_EL2 && vhe_supported() && !vhe_enabled(),
+			"CPU(%3d) VHE disable", cpu);
+
+	enable_vhe();
+	report(current_level() == CurrentEL_EL2 && vhe_supported() && vhe_enabled(),
+			"CPU(%3d) VHE re-enable", cpu);
 }
 
 static bool psci_check(void);
-- 
2.7.4