On Wed, Nov 07, 2018 at 05:10:31PM +0000, Alex Bennée wrote: > Not all faults handled by handle_exit are instruction emulations. For > example a ESR_ELx_EC_IABT will result in the page tables being updated > but the instruction that triggered the fault hasn't actually executed > yet. We use the simple heuristic of checking for a changed PC before > seeing if kvm_arm_handle_step_debug wants to claim we stepped an > instruction. > > Signed-off-by: Alex Bennée <[email protected]> > --- > arch/arm64/kvm/handle_exit.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c > index e5e741bfffe1..b8252e72f882 100644 > --- a/arch/arm64/kvm/handle_exit.c > +++ b/arch/arm64/kvm/handle_exit.c > @@ -214,6 +214,7 @@ static exit_handle_fn kvm_get_exit_handler(struct > kvm_vcpu *vcpu) > static int handle_trap_exceptions(struct kvm_vcpu *vcpu, struct kvm_run *run) > { > int handled; > + unsigned long old_pc = *vcpu_pc(vcpu); > > /* > * See ARM ARM B1.14.1: "Hyp traps on instructions > @@ -233,7 +234,8 @@ static int handle_trap_exceptions(struct kvm_vcpu *vcpu, > struct kvm_run *run) > * kvm_arm_handle_step_debug() sets the exit_reason on the kvm_run > * structure if we need to return to userspace. > */ > - if (handled > 0 && kvm_arm_handle_step_debug(vcpu, run)) > + if (handled > 0 && *vcpu_pc(vcpu) != old_pc &&
This doesn't work if the emulation is equivalent to a branch-to-self, so I don't think that we want to do this. When are we failing to advance the single-step state machine correctly? Thanks, Mark. > + kvm_arm_handle_step_debug(vcpu, run)) > handled = 0; > > return handled; > -- > 2.17.1 > _______________________________________________ kvmarm mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
