linux-kernel - Re: [PATCH 4/4] KVM: riscv: selftests: Selectively filter-out AIA registers

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Message-ID: <20230920-bc0e3956d144be651727e252@orel>
Date:   Wed, 20 Sep 2023 06:48:11 +0200
From:   Andrew Jones <ajones@...tanamicro.com>
To:     Atish Patra <atishp@...shpatra.org>
Cc:     Anup Patel <apatel@...tanamicro.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Shuah Khan <shuah@...nel.org>,
        Palmer Dabbelt <palmer@...belt.com>,
        Paul Walmsley <paul.walmsley@...ive.com>, kvm@...r.kernel.org,
        kvm-riscv@...ts.infradead.org, linux-riscv@...ts.infradead.org,
        linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH 4/4] KVM: riscv: selftests: Selectively filter-out AIA
 registers

On Tue, Sep 19, 2023 at 01:12:47PM -0700, Atish Patra wrote:
> On Mon, Sep 18, 2023 at 11:07 AM Anup Patel <apatel@...tanamicro.com> wrote:
> >
> > Currently the AIA ONE_REG registers are reported by get-reg-list
> > as new registers for various vcpu_reg_list configs whenever Ssaia
> > is available on the host because Ssaia extension can only be
> > disabled by Smstateen extension which is not always available.
> >
> > To tackle this, we should filter-out AIA ONE_REG registers only
> > when Ssaia can't be disabled for a VCPU.
> >
> > Fixes: 477069398ed6 ("KVM: riscv: selftests: Add get-reg-list test")
> > Signed-off-by: Anup Patel <apatel@...tanamicro.com>
> > ---
> >  .../selftests/kvm/riscv/get-reg-list.c        | 23 +++++++++++++++++--
> >  1 file changed, 21 insertions(+), 2 deletions(-)
> >
> > diff --git a/tools/testing/selftests/kvm/riscv/get-reg-list.c b/tools/testing/selftests/kvm/riscv/get-reg-list.c
> > index 76c0ad11e423..85907c86b835 100644
> > --- a/tools/testing/selftests/kvm/riscv/get-reg-list.c
> > +++ b/tools/testing/selftests/kvm/riscv/get-reg-list.c
> > @@ -12,6 +12,8 @@
> >
> >  #define REG_MASK (KVM_REG_ARCH_MASK | KVM_REG_SIZE_MASK)
> >
> > +static bool isa_ext_cant_disable[KVM_RISCV_ISA_EXT_MAX];
> > +
> >  bool filter_reg(__u64 reg)
> >  {
> >         switch (reg & ~REG_MASK) {
> > @@ -48,6 +50,15 @@ bool filter_reg(__u64 reg)
> >         case KVM_REG_RISCV_ISA_EXT | KVM_RISCV_ISA_EXT_ZIFENCEI:
> >         case KVM_REG_RISCV_ISA_EXT | KVM_RISCV_ISA_EXT_ZIHPM:
> >                 return true;
> > +       /* AIA registers are always available when Ssaia can't be disabled */
> > +       case KVM_REG_RISCV_CSR | KVM_REG_RISCV_CSR_AIA | KVM_REG_RISCV_CSR_AIA_REG(siselect):
> > +       case KVM_REG_RISCV_CSR | KVM_REG_RISCV_CSR_AIA | KVM_REG_RISCV_CSR_AIA_REG(iprio1):
> > +       case KVM_REG_RISCV_CSR | KVM_REG_RISCV_CSR_AIA | KVM_REG_RISCV_CSR_AIA_REG(iprio2):
> > +       case KVM_REG_RISCV_CSR | KVM_REG_RISCV_CSR_AIA | KVM_REG_RISCV_CSR_AIA_REG(sieh):
> > +       case KVM_REG_RISCV_CSR | KVM_REG_RISCV_CSR_AIA | KVM_REG_RISCV_CSR_AIA_REG(siph):
> > +       case KVM_REG_RISCV_CSR | KVM_REG_RISCV_CSR_AIA | KVM_REG_RISCV_CSR_AIA_REG(iprio1h):
> > +       case KVM_REG_RISCV_CSR | KVM_REG_RISCV_CSR_AIA | KVM_REG_RISCV_CSR_AIA_REG(iprio2h):
> > +               return isa_ext_cant_disable[KVM_RISCV_ISA_EXT_SSAIA] ? true : false;
> 
> Ahh I guess. you do need the switch case for AIA CSRs but for ISA
> extensions can be avoided as it is contiguous.

I guess we could so something like

case KVM_REG_RISCV_ISA_EXT ... KVM_REG_RISCV_ISA_EXT | KVM_RISCV_ISA_EXT_MAX:

for the ISA extensions.

Thanks,
drew