Re: [PATCH 00/16] target/arm: sve load/store improvements

[Peter Maydell]

On Wed, 11 Mar 2020 at 06:44, Richard Henderson
<address@hidden> wrote:
>
> The goal here is to support MTE, but there's some cleanup to do.
>
> Technically, we have sufficient interfaces in cputlb.c now, but it
> requires multiple tlb lookups on different interfaces to do so.
>
> Adding probe_access_flags() allows probing the tlb and getting out
> some of the flags buried in the tlb comparator, such as TLB_MMIO
> and TLB_WATCHPOINT.  In addition, we get no-fault semantics,
> which we don't have via probe_acccess().
>
> Adding cpu_probe_watchpoint() allows to *not* stop a first-fault
> or no-fault load when the page contains a watchpoint, but the actual
> access does not hit.
>
> Having these available means that we can handle all of the watchpoints
> for a given set of loads/stores all at once, before we begin doing any
> actual memory operations.  Further, the actual memory operation on a
> page of ram that has a watchpoint can still use the fast path.
>
> Looking forward to MTE, we can examine the Tagged bit on a per-page
> basis and avoid dozens of mte_check calls that must be Unchecked.
> That comes later, in a new version of the MTE patch set, but I do
> add comments for where the checks should be added.

Series reviewed; I didn't bother to flag up the checkpatch
complaints, but I think all but one of them are legit, so
please fix those too.

thanks
-- PMM