linux-kernel - Re: [PATCH v6 06/20] KVM: selftests: Add vcpu_set_cpuid

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Message-ID: <CALMp9eTQiom+0b5qPP_0u2tGqw9GcWbJVMNGeNZms8MTH8byuQ@mail.gmail.com>
Date:   Sat, 4 Nov 2023 05:51:45 -0700
From:   Jim Mattson <jmattson@...gle.com>
To:     Sean Christopherson <seanjc@...gle.com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Kan Liang <kan.liang@...ux.intel.com>,
        Dapeng Mi <dapeng1.mi@...ux.intel.com>,
        Jinrong Liang <cloudliang@...cent.com>,
        Like Xu <likexu@...cent.com>,
        Aaron Lewis <aaronlewis@...gle.com>
Subject: Re: [PATCH v6 06/20] KVM: selftests: Add vcpu_set_cpuid_property() to
 set properties

On Fri, Nov 3, 2023 at 5:02 PM Sean Christopherson <seanjc@...gle.com> wrote:
>
> From: Jinrong Liang <cloudliang@...cent.com>
>
> Add vcpu_set_cpuid_property() helper function for setting properties, and
> use it instead of open coding an equivalent for MAX_PHY_ADDR.  Future vPMU
> testcases will also need to stuff various CPUID properties.
>
> Signed-off-by: Jinrong Liang <cloudliang@...cent.com>
> Co-developed-by: Sean Christopherson <seanjc@...gle.com>
> Signed-off-by: Sean Christopherson <seanjc@...gle.com>
> ---
>  .../testing/selftests/kvm/include/x86_64/processor.h |  4 +++-
>  tools/testing/selftests/kvm/lib/x86_64/processor.c   | 12 +++++++++---
>  .../kvm/x86_64/smaller_maxphyaddr_emulation_test.c   |  2 +-
>  3 files changed, 13 insertions(+), 5 deletions(-)
>
> diff --git a/tools/testing/selftests/kvm/include/x86_64/processor.h b/tools/testing/selftests/kvm/include/x86_64/processor.h
> index 25bc61dac5fb..a01931f7d954 100644
> --- a/tools/testing/selftests/kvm/include/x86_64/processor.h
> +++ b/tools/testing/selftests/kvm/include/x86_64/processor.h
> @@ -994,7 +994,9 @@ static inline void vcpu_set_cpuid(struct kvm_vcpu *vcpu)
>         vcpu_ioctl(vcpu, KVM_GET_CPUID2, vcpu->cpuid);
>  }
>
> -void vcpu_set_cpuid_maxphyaddr(struct kvm_vcpu *vcpu, uint8_t maxphyaddr);
> +void vcpu_set_cpuid_property(struct kvm_vcpu *vcpu,
> +                            struct kvm_x86_cpu_property property,
> +                            uint32_t value);
>
>  void vcpu_clear_cpuid_entry(struct kvm_vcpu *vcpu, uint32_t function);
>  void vcpu_set_or_clear_cpuid_feature(struct kvm_vcpu *vcpu,
> diff --git a/tools/testing/selftests/kvm/lib/x86_64/processor.c b/tools/testing/selftests/kvm/lib/x86_64/processor.c
> index d8288374078e..9e717bc6bd6d 100644
> --- a/tools/testing/selftests/kvm/lib/x86_64/processor.c
> +++ b/tools/testing/selftests/kvm/lib/x86_64/processor.c
> @@ -752,11 +752,17 @@ void vcpu_init_cpuid(struct kvm_vcpu *vcpu, const struct kvm_cpuid2 *cpuid)
>         vcpu_set_cpuid(vcpu);
>  }
>
> -void vcpu_set_cpuid_maxphyaddr(struct kvm_vcpu *vcpu, uint8_t maxphyaddr)
> +void vcpu_set_cpuid_property(struct kvm_vcpu *vcpu,
> +                            struct kvm_x86_cpu_property property,
> +                            uint32_t value)
>  {
> -       struct kvm_cpuid_entry2 *entry = vcpu_get_cpuid_entry(vcpu, 0x80000008);
> +       struct kvm_cpuid_entry2 *entry;
> +
> +       entry = __vcpu_get_cpuid_entry(vcpu, property.function, property.index);
> +
> +       (&entry->eax)[property.reg] &= ~GENMASK(property.hi_bit, property.lo_bit);
> +       (&entry->eax)[property.reg] |= value << (property.lo_bit);

What if 'value' is too large?

Perhaps:
         value <<= property.lo_bit;
         TEST_ASSERT(!(value & ~GENMASK(property.hi_bit,
property.lo_bit)), "value is too large");
         (&entry->eax)[property.reg] |= value;

> -       entry->eax = (entry->eax & ~0xff) | maxphyaddr;
>         vcpu_set_cpuid(vcpu);
>  }
>
> diff --git a/tools/testing/selftests/kvm/x86_64/smaller_maxphyaddr_emulation_test.c b/tools/testing/selftests/kvm/x86_64/smaller_maxphyaddr_emulation_test.c
> index 06edf00a97d6..9b89440dff19 100644
> --- a/tools/testing/selftests/kvm/x86_64/smaller_maxphyaddr_emulation_test.c
> +++ b/tools/testing/selftests/kvm/x86_64/smaller_maxphyaddr_emulation_test.c
> @@ -63,7 +63,7 @@ int main(int argc, char *argv[])
>         vm_init_descriptor_tables(vm);
>         vcpu_init_descriptor_tables(vcpu);
>
> -       vcpu_set_cpuid_maxphyaddr(vcpu, MAXPHYADDR);
> +       vcpu_set_cpuid_property(vcpu, X86_PROPERTY_MAX_PHY_ADDR, MAXPHYADDR);
>
>         rc = kvm_check_cap(KVM_CAP_EXIT_ON_EMULATION_FAILURE);
>         TEST_ASSERT(rc, "KVM_CAP_EXIT_ON_EMULATION_FAILURE is unavailable");
> --
> 2.42.0.869.gea05f2083d-goog
>