On Thu, Feb 01, 2018 at 11:46:42AM +0000, Marc Zyngier wrote:
> When handling an SMC trap, the "preferred return address" is set
> to that of the SMC, and not the next PC (which is a departure from
> the behaviour of an SMC that isn't trapped).
>
> Increment PC in the handler, as the guest is otherwise forever
> stuck...
>
Reviewed-by: Christoffer Dall <christoffer.d...@linaro.org>
> Cc: sta...@vger.kernel.org
> Fixes: acfb3b883f6d ("arm64: KVM: Fix SMCCC handling of unimplemented SMC/HVC
> calls")
> Signed-off-by: Marc Zyngier <marc.zyng...@arm.com>
> ---
> arch/arm64/kvm/handle_exit.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c
> index 520b0dad3c62..5493bbefbd0d 100644
> --- a/arch/arm64/kvm/handle_exit.c
> +++ b/arch/arm64/kvm/handle_exit.c
> @@ -62,7 +62,16 @@ static int handle_hvc(struct kvm_vcpu *vcpu, struct
> kvm_run *run)
>
> static int handle_smc(struct kvm_vcpu *vcpu, struct kvm_run *run)
> {
> + /*
> + * "If an SMC instruction executed at Non-secure EL1 is
> + * trapped to EL2 because HCR_EL2.TSC is 1, the exception is a
> + * Trap exception, not a Secure Monitor Call exception [...]"
> + *
> + * We need to advance the PC after the trap, as it would
> + * otherwise return to the same address...
> + */
> vcpu_set_reg(vcpu, 0, ~0UL);
> + kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
> return 1;
> }
>
> --
> 2.14.2
>
