[PATCH v2 4/4] KVM: arm64: selftests: Add a test case for KVM_GUESTDBG_SINGLESTEP

[Reiji Watanabe]

Hi Marc,

On Mon, Sep 19, 2022 at 2:36 AM Marc Zyngier <maz at kernel.org> wrote:
>
> On Sat, 17 Sep 2022 02:06:00 +0100,
> Reiji Watanabe <reijiw at google.com> wrote:
> >
> > Add a test case for KVM_GUESTDBG_SINGLESTEP to the debug-exceptions test.
> > The test enables single-step execution from userspace, and check if the
> > exit to userspace occurs for each instruction that is stepped.
> > Set the default number of the test iterations to a number of iterations
> > sufficient to always reproduce the problem that the previous patch fixes
> > on an Ampere Altra machine.
>
> A possibly more aggressive version of this test would be to force a
> (short lived) timer to fire on the same CPU, forcing an exit. This
> should hopefully result in a more predictable way to trigger the
> issue. But that's a reasonable test as a start.

Yes, that could result in a more predictable way to cause the specific case!
I will consider this at a future opportunity.

Thank you,
Reiji