Re: [Qemu-devel] [PATCH 00/13] target/ppc improve atomic operations

[David Gibson <david@gibson.dropbear.id.au>]

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On Tue, Jun 26, 2018 at 09:19:08AM -0700, Richard Henderson wrote:
> In another patch set this week, I had noticed the old linux-user
> do_store_exclusive code was still present.  I had thought that was
> dead code that simply hadn't been removed, but it turned out that
> we had not completed the transition to tcg atomics for linux-user.
> 
> In the process, I discovered that we weren't using atomic operations
> for the 128-bit lq, lqarx, and stqcx insns.  These would have simply
> produced incorrect results for -smp in system mode.
> 
> I tidy the code a bit by making use of MO_ALIGN, which means that
> we don't need a separate explicit alignment check.
> 
> I use the new min/max atomic operations I added recently for
> ARMv8.2-Atomics and RISC-V.
> 
> Finally, Power9 has some *really* odd atomic operations in its
> l[wd]at and st[wd]at instructions.  We were generating illegal
> instruction for these.  I implement them for serial context and
> force parallel context to grab the exclusive lock and try again.
> 
> Except for the trivial linux-user ll/sc case, I do not have any
> code that exercises these instructions.  Perhaps the IBM folk
> have something that can test the others?

I've now applied the whole series to ppc-for-3.0.

> 
> 
> r~
> 
> 
> Richard Henderson (13):
>   target/ppc: Add do_unaligned_access hook
>   target/ppc: Use atomic load for LQ and LQARX
>   target/ppc: Use atomic store for STQ
>   target/ppc: Use atomic cmpxchg for STQCX
>   target/ppc: Remove POWERPC_EXCP_STCX
>   target/ppc: Tidy gen_conditional_store
>   target/ppc: Split out gen_load_locked
>   target/ppc: Split out gen_ld_atomic
>   target/ppc: Split out gen_st_atomic
>   target/ppc: Use MO_ALIGN for EXIWX and ECOWX
>   target/ppc: Use atomic min/max helpers
>   target/ppc: Implement the rest of gen_ld_atomic
>   target/ppc: Implement the rest of gen_st_atomic
> 
>  target/ppc/cpu.h                |   8 +-
>  target/ppc/helper.h             |  11 +
>  target/ppc/internal.h           |   5 +
>  linux-user/ppc/cpu_loop.c       | 123 ++----
>  target/ppc/excp_helper.c        |  18 +-
>  target/ppc/mem_helper.c         |  72 +++-
>  target/ppc/translate.c          | 648 ++++++++++++++++++++------------
>  target/ppc/translate_init.inc.c |   1 +
>  8 files changed, 539 insertions(+), 347 deletions(-)
> 

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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