[PATCH 1/5] arm/arm64: KVM: Don't BUG_ON if IT bits are set in ARM mode

Marc Zyngier
2016-08-19T12:38:11Z

The ARM ARM asserts that having the IT bits set in ARM mode is
unpredictable. But should a CPU do that (and still be able to
run correctly), we shouldn't kill the system.

So let's drop the BUG_ON that checks for this, as it is not
very helpful.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
arch/arm/kvm/emulate.c | 4 +---
arch/arm64/kvm/emulate.c | 4 +---
2 files changed, 2 insertions(+), 6 deletions(-)

diff --git a/arch/arm/kvm/emulate.c b/arch/arm/kvm/emulate.c
index af93e3f..eda9ddd 100644
--- a/arch/arm/kvm/emulate.c
+++ b/arch/arm/kvm/emulate.c
@@ -221,9 +221,7 @@ static void kvm_adjust_itstate(struct kvm_vcpu *vcpu)
unsigned long cpsr = *vcpu_cpsr(vcpu);
bool is_arm = !(cpsr & PSR_T_BIT);

- BUG_ON(is_arm && (cpsr & PSR_IT_MASK));
-
- if (!(cpsr & PSR_IT_MASK))
+ if (is_arm || !(cpsr & PSR_IT_MASK))
return;

cond = (cpsr & 0xe000) >> 13;
diff --git a/arch/arm64/kvm/emulate.c b/arch/arm64/kvm/emulate.c
index f87d8fb..df76590 100644
--- a/arch/arm64/kvm/emulate.c
+++ b/arch/arm64/kvm/emulate.c
@@ -120,9 +120,7 @@ static void kvm_adjust_itstate(struct kvm_vcpu *vcpu)
unsigned long cpsr = *vcpu_cpsr(vcpu);
bool is_arm = !(cpsr & COMPAT_PSR_T_BIT);

- BUG_ON(is_arm && (cpsr & COMPAT_PSR_IT_MASK));
-
- if (!(cpsr & COMPAT_PSR_IT_MASK))
+ if (is_arm || !(cpsr & COMPAT_PSR_IT_MASK))
return;

cond = (cpsr & 0xe000) >> 13;
--
2.1.4