[PATCH v2 12/12] KVM: arm64: BTI: Reset BTYPE when skipping emulated instructions

From: Dave Martin
Date: Thu Oct 10 2019 - 14:46:20 EST


Since normal execution of any non-branch instruction resets the
PSTATE BTYPE field to 0, so do the same thing when emulating a
trapped instruction.

Branches don't trap directly, so we should never need to assign a
non-zero value to BTYPE here.

Signed-off-by: Dave Martin <Dave.Martin@xxxxxxx>
---
arch/arm64/include/asm/kvm_emulate.h | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h
index d69c1ef..33957a12 100644
--- a/arch/arm64/include/asm/kvm_emulate.h
+++ b/arch/arm64/include/asm/kvm_emulate.h
@@ -452,8 +452,10 @@ static inline void kvm_skip_instr(struct kvm_vcpu *vcpu, bool is_wide_instr)
{
if (vcpu_mode_is_32bit(vcpu))
kvm_skip_instr32(vcpu, is_wide_instr);
- else
+ else {
*vcpu_pc(vcpu) += 4;
+ *vcpu_cpsr(vcpu) &= ~(u64)PSR_BTYPE_MASK;
+ }

/* advance the singlestep state machine */
*vcpu_cpsr(vcpu) &= ~DBG_SPSR_SS;
--
2.1.4