[PATCH v8 0/4] arm64: mte: allow async MTE to be upgraded to sync on a per-CPU basis

[Catalin Marinas]

On Wed, Jun 30, 2021 at 04:15:05PM -0700, Peter Collingbourne wrote:
> On some CPUs the performance of MTE in synchronous mode is similar
> to that of asynchronous mode. This makes it worthwhile to enable
> synchronous mode on those CPUs when asynchronous mode is requested,
> in order to gain the error detection benefits of synchronous mode
> without the performance downsides. Therefore, make it possible for
> user programs to opt into upgrading to synchronous mode on those CPUs.
> 
> This is done by introducing a notion of a preferred TCF mode, which is
> controlled on a per-CPU basis by a sysfs node. The existing SYNC and
> ASYNC TCF settings are repurposed as bitfields that specify a set of
> possible modes. If the preferred TCF mode for a particular CPU is in
> the user-provided mode set (this will always be the case for mode sets
> containing more than one mode because the kernel only supports two tag
> checking modes, but future kernels may support more modes) then that
> mode is used when running on that CPU, otherwise one of the modes in
> the task's mode set will be selected in a currently unspecified manner.

The series looks good to me but please post it again after -rc1 if it
doesn't apply cleanly.

Thanks.

-- 
Catalin