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Re: [RFC PATCH v3 0/3] Implement Power ISA 3.1B hash insns

From: Víctor Colombo
Subject: Re: [RFC PATCH v3 0/3] Implement Power ISA 3.1B hash insns
Date: Fri, 15 Jul 2022 10:36:01 -0300
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0

On 15/07/2022 10:23, Daniel Henrique Barboza wrote:
On 7/13/22 13:54, Víctor Colombo wrote:
This patch series implements the 4 instructions added in Power ISA

- hashchk
- hashst
- hashchkp
- hashstp

To build it, you need to apply the following patches on top of master:

Working branch for ease of use can be found here:

What do you think about the choice to implement the hash algorithm
from the ground up, following the SIMON-like algorithm presented in
Power ISA? IIUC, this algorithm is not the same as the original[1].
Other options would be to use other algorithm already implemented
in QEMU, or even make this instruction a nop for all Power versions.

Also, I was thinking about using the call to spr_register_kvm() in
init_proc_POWER10 to initialize the registers with a random value.
I'm not sure what is the behavior here, I would expect that is the job
of the OS to set the regs, but looks like KVM is not exporting them,
so they are always 0 (?). Does anyone have any insight on this?

This happens because KVM on POWER10 isn't handling these registers
appropriately. We are probably missing kernel/kvm code to do so.

Since KVM on POWER10 is on an uncertain spot at this moment I wouldn't
worry too much about it. Making the regs read/write work in TCG is good
enough for now.


Hello Daniel,

Thanks for taking a look at this. I agree that in this case it is better
to make it work in TCG and drop the KVM part from this patch set
I'll work on it now


- Split the patch in 2
- Rebase to master

- Split patches in 3
     - the new patch (patch 1) is separating the kvm header
       changes [Cornelia]

[1] https://eprint.iacr.org/2013/404.pdf

Víctor Colombo (3):
   linux-headers/asm-powerpc/kvm.h: Add HASHKEYR and HASHPKEYR in headers
   target/ppc: Implement hashst and hashchk
   target/ppc: Implement hashstp and hashchkp

  linux-headers/asm-powerpc/kvm.h            |  3 +
  target/ppc/cpu.h                           |  2 +
  target/ppc/cpu_init.c                      |  7 ++
  target/ppc/excp_helper.c                   | 82 ++++++++++++++++++++++
  target/ppc/helper.h                        |  4 ++
  target/ppc/insn32.decode                   | 10 +++
  target/ppc/translate.c                     |  5 ++
  target/ppc/translate/fixedpoint-impl.c.inc | 34 +++++++++
  8 files changed, 147 insertions(+)

Víctor Cora Colombo
Instituto de Pesquisas ELDORADO
Aviso Legal - Disclaimer <https://www.eldorado.org.br/disclaimer.html>

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