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

[Víctor Colombo]

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
> > 3.1B:
> >
> > - hashchk
> > - hashst
> > - hashchkp
> > - hashstp
> >
> > To build it, you need to apply the following patches on top of master:
> > <20220701133507.740619-2-lucas.coutinho@eldorado.org.br>
> > <20220701133507.740619-3-lucas.coutinho@eldorado.org.br>
> > <20220712193741.59134-2-leandro.lupori@eldorado.org.br>
> > <20220712193741.59134-3-leandro.lupori@eldorado.org.br>
> >
> > Working branch for ease of use can be found here:
> > https://github.com/PPC64/qemu/tree/vccolombo-hash-to-send-v3
> >
> > 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.
>
>
> Daniel

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

Thanks!

> > v1->v2:
> > - Split the patch in 2
> > - Rebase to master
> >
> > v2->v3:
> > - 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
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