[kvm-unit-tests,0/3] arm: pmu: Fixes for bare metal

Message

Ricardo Koller July 18, 2022, 3:49 p.m. UTC

There are some tests that fail when running on bare metal (including a
passthrough prototype).  There are three issues with the tests.  The
first one is that there are some missing isb()'s between enabling event
counting and the actual counting. This wasn't an issue on KVM as
trapping on registers served as context synchronization events. The
second issue is that some tests assume that registers reset to 0.  And
finally, the third issue is that overflowing the low counter of a
chained event sets the overflow flag in PMVOS and some tests fail by
checking for it not being set.

I believe the third fix also requires a KVM change, but would like to
double check with others first.  The only reference I could find in the
ARM ARM is the AArch64.IncrementEventCounter() pseudocode (DDI 0487H.a,
J1.1.1 "aarch64/debug") that unconditionally sets the PMOVS bit on
overflow.

Ricardo Koller (3):
  arm: pmu: Add missing isb()'s after sys register writing
  arm: pmu: Reset the pmu registers before starting some tests
  arm: pmu: Remove checks for !overflow in chained counters tests

 arm/pmu.c | 34 +++++++++++++++++++++++-----------
 1 file changed, 23 insertions(+), 11 deletions(-)

Comments

Alexandru Elisei July 18, 2022, 4:42 p.m. UTC | #1

Hi,

I believe you're missing the updated email for the arm maintainer. Added it.

Thanks,
Alex

On Mon, Jul 18, 2022 at 08:49:07AM -0700, Ricardo Koller wrote:
> There are some tests that fail when running on bare metal (including a
> passthrough prototype).  There are three issues with the tests.  The
> first one is that there are some missing isb()'s between enabling event
> counting and the actual counting. This wasn't an issue on KVM as
> trapping on registers served as context synchronization events. The
> second issue is that some tests assume that registers reset to 0.  And
> finally, the third issue is that overflowing the low counter of a
> chained event sets the overflow flag in PMVOS and some tests fail by
> checking for it not being set.
> 
> I believe the third fix also requires a KVM change, but would like to
> double check with others first.  The only reference I could find in the
> ARM ARM is the AArch64.IncrementEventCounter() pseudocode (DDI 0487H.a,
> J1.1.1 "aarch64/debug") that unconditionally sets the PMOVS bit on
> overflow.
> 
> Ricardo Koller (3):
>   arm: pmu: Add missing isb()'s after sys register writing
>   arm: pmu: Reset the pmu registers before starting some tests
>   arm: pmu: Remove checks for !overflow in chained counters tests
> 
>  arm/pmu.c | 34 +++++++++++++++++++++++-----------
>  1 file changed, 23 insertions(+), 11 deletions(-)
> 
> -- 
> 2.37.0.170.g444d1eabd0-goog
>

Ricardo Koller July 18, 2022, 5:18 p.m. UTC | #2

On Mon, Jul 18, 2022 at 05:42:08PM +0100, Alexandru Elisei wrote:
> Hi,
> 
> I believe you're missing the updated email for the arm maintainer. Added it.
> 
> Thanks,
> Alex
> 
> On Mon, Jul 18, 2022 at 08:49:07AM -0700, Ricardo Koller wrote:
> > There are some tests that fail when running on bare metal (including a
> > passthrough prototype).  There are three issues with the tests.  The
> > first one is that there are some missing isb()'s between enabling event
> > counting and the actual counting. This wasn't an issue on KVM as
> > trapping on registers served as context synchronization events. The
> > second issue is that some tests assume that registers reset to 0.  And
> > finally, the third issue is that overflowing the low counter of a
> > chained event sets the overflow flag in PMVOS and some tests fail by
> > checking for it not being set.
> > 
> > I believe the third fix also requires a KVM change, but would like to
> > double check with others first.  The only reference I could find in the
> > ARM ARM is the AArch64.IncrementEventCounter() pseudocode (DDI 0487H.a,
> > J1.1.1 "aarch64/debug") that unconditionally sets the PMOVS bit on
> > overflow.
> > 
> > Ricardo Koller (3):
> >   arm: pmu: Add missing isb()'s after sys register writing
> >   arm: pmu: Reset the pmu registers before starting some tests
> >   arm: pmu: Remove checks for !overflow in chained counters tests
> > 
> >  arm/pmu.c | 34 +++++++++++++++++++++++-----------
> >  1 file changed, 23 insertions(+), 11 deletions(-)
> > 
> > -- 
> > 2.37.0.170.g444d1eabd0-goog
> > 

Right, I forgot about the new email. Thanks for the forwarding!