Re: [PATCH v2 09/11] KVM: riscv: selftests: Make check_supported arch specific

From: Haibo Xu <xiaobo55x@gmail.com>
To: Andrew Jones <ajones@ventanamicro.com>
Cc: Haibo Xu <haibo1.xu@intel.com>,
	maz@kernel.org, oliver.upton@linux.dev,  seanjc@google.com,
	Paolo Bonzini <pbonzini@redhat.com>,
	Jonathan Corbet <corbet@lwn.net>,
	 Anup Patel <anup@brainfault.org>,
	Atish Patra <atishp@atishpatra.org>,
	 Paul Walmsley <paul.walmsley@sifive.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	 Albert Ou <aou@eecs.berkeley.edu>, Shuah Khan <shuah@kernel.org>,
	 James Morse <james.morse@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	 Zenghui Yu <yuzenghui@huawei.com>,
	David Matlack <dmatlack@google.com>,
	 Ben Gardon <bgardon@google.com>,
	Vipin Sharma <vipinsh@google.com>,
	 Colton Lewis <coltonlewis@google.com>,
	kvm@vger.kernel.org, linux-doc@vger.kernel.org,
	 linux-kernel@vger.kernel.org, kvm-riscv@lists.infradead.org,
	 linux-riscv@lists.infradead.org,
	linux-kselftest@vger.kernel.org,
	 linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev
Subject: Re: [PATCH v2 09/11] KVM: riscv: selftests: Make check_supported arch specific
Date: Fri, 26 May 2023 15:50:32 +0800	[thread overview]
Message-ID: <CAJve8onF9MFuaVsThFnhjWr6ZomB0Lhr9WXGvMiJDt5vrjeKLg@mail.gmail.com> (raw)
In-Reply-To: <20230525-705ddcbcd43aa63e3fd356c8@orel>

On Fri, May 26, 2023 at 12:40 AM Andrew Jones <ajones@ventanamicro.com> wrote:
>
> On Thu, May 25, 2023 at 03:38:33PM +0800, Haibo Xu wrote:
> > check_supported() was used to verify whether a feature/extension was
> > supported in a guest in the get-reg-list test. Currently this info
> > can be retrieved through the KVM_CAP_ARM_* API in aarch64, but in
> > riscv, this info was only exposed through the KVM_GET_ONE_REG on
> > KVM_REG_RISCV_ISA_EXT pseudo registers.
> >
> > Signed-off-by: Haibo Xu <haibo1.xu@intel.com>
> > ---
> >  tools/testing/selftests/kvm/get-reg-list.c | 32 +++++++++++-----------
> >  1 file changed, 16 insertions(+), 16 deletions(-)
> >
> > diff --git a/tools/testing/selftests/kvm/get-reg-list.c b/tools/testing/selftests/kvm/get-reg-list.c
> > index f6ad7991a812..f1fc113e9719 100644
> > --- a/tools/testing/selftests/kvm/get-reg-list.c
> > +++ b/tools/testing/selftests/kvm/get-reg-list.c
> > @@ -99,6 +99,20 @@ void __weak print_reg(const char *prefix, __u64 id)
> >  }
> >
> >  #ifdef __aarch64__
> > +static void check_supported(struct vcpu_reg_list *c)
> > +{
> > +     struct vcpu_reg_sublist *s;
> > +
> > +     for_each_sublist(c, s) {
> > +             if (!s->capability)
> > +                     continue;
>
> I was going to say that making this function aarch64 shouldn't be
> necessary, since riscv leaves capability set to zero and this function
> doesn't do anything, but then looking ahead I see riscv is abusing
> capability by putting isa extensions in it. IMO, capability should
> only be set to KVM_CAP_* values. Since riscv doesn't use it, then it
> should be left zero.
>
> If we're going to abuse something, then I'd rather abuse the 'feature'
> member, but since it's only an int (not an unsigned long), then let's
> just add an 'unsigned long extension' member.
>

Good idea!

For the new 'extension' member in riscv, I think its use case should be
identical to the 'feature' member in aarch64(KVM_RISCV_ISA_EXT_F
was similar to KVM_ARM_VCPU_SVE)? If so, I think we can just reuse
the 'feature' member since the data type was not a big deal.

> Then, the finalize_vcpu() call can be moved back to run_test(), from
> aarch64's vcpu_config_get_vcpu(). Both aarch64 and riscv will call it
> right after vcpu_config_get_vcpu() and the riscv version of it will
> do what your current riscv check_supported() is doing, using the
> new 'extension' member instead of 'capability'.
>
> And this patch gets dropped.
>
> Thanks,
> drew
>
> > +
> > +             __TEST_REQUIRE(kvm_has_cap(s->capability),
> > +                            "%s: %s not available, skipping tests\n",
> > +                            config_name(c), s->name);
> > +     }
> > +}
> > +
> >  static void prepare_vcpu_init(struct vcpu_reg_list *c, struct kvm_vcpu_init *init)
> >  {
> >       struct vcpu_reg_sublist *s;
> > @@ -126,6 +140,8 @@ static struct kvm_vcpu *vcpu_config_get_vcpu(struct vcpu_reg_list *c, struct kvm
> >       struct kvm_vcpu_init init = { .target = -1, };
> >       struct kvm_vcpu *vcpu;
> >
> > +     check_supported(c);
> > +
> >       prepare_vcpu_init(c, &init);
> >       vcpu = __vm_vcpu_add(vm, 0);
> >       aarch64_vcpu_setup(vcpu, &init);
> > @@ -140,20 +156,6 @@ static struct kvm_vcpu *vcpu_config_get_vcpu(struct vcpu_reg_list *c, struct kvm
> >  }
> >  #endif
> >
> > -static void check_supported(struct vcpu_reg_list *c)
> > -{
> > -     struct vcpu_reg_sublist *s;
> > -
> > -     for_each_sublist(c, s) {
> > -             if (!s->capability)
> > -                     continue;
> > -
> > -             __TEST_REQUIRE(kvm_has_cap(s->capability),
> > -                            "%s: %s not available, skipping tests\n",
> > -                            config_name(c), s->name);
> > -     }
> > -}
> > -
> >  static bool print_list;
> >  static bool print_filtered;
> >
> > @@ -165,8 +167,6 @@ static void run_test(struct vcpu_reg_list *c)
> >       struct kvm_vm *vm;
> >       struct vcpu_reg_sublist *s;
> >
> > -     check_supported(c);
> > -
> >       vm = vm_create_barebones();
> >       vcpu = vcpu_config_get_vcpu(c, vm);
> >
> > --
> > 2.34.1
> >

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