linux-kernel - Re: [PATCH v3 10/25] KVM: selftests: Enable TSC scaling in evmcs selftest

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Date:   Tue, 12 Jul 2022 14:54:11 +0300
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     Vitaly Kuznetsov <vkuznets@...hat.com>, kvm@...r.kernel.org,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>
Cc:     Anirudh Rayabharam <anrayabh@...ux.microsoft.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        linux-hyperv@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 10/25] KVM: selftests: Enable TSC scaling in evmcs
 selftest

On Fri, 2022-07-08 at 16:42 +0200, Vitaly Kuznetsov wrote:
> The updated Enlightened VMCS v1 definition enables TSC scaling, test
> that SECONDARY_EXEC_TSC_SCALING can now be enabled.
> 
> Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
> ---
>  .../testing/selftests/kvm/x86_64/evmcs_test.c | 31 +++++++++++++++++--
>  1 file changed, 29 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/testing/selftests/kvm/x86_64/evmcs_test.c b/tools/testing/selftests/kvm/x86_64/evmcs_test.c
> index 8dda527cc080..80135b98dc3b 100644
> --- a/tools/testing/selftests/kvm/x86_64/evmcs_test.c
> +++ b/tools/testing/selftests/kvm/x86_64/evmcs_test.c
> @@ -18,6 +18,9 @@
>  
>  #include "vmx.h"
>  
> +/* Test flags */
> +#define HOST_HAS_TSC_SCALING BIT(0)
> +
>  static int ud_count;
>  
>  static void guest_ud_handler(struct ex_regs *regs)
> @@ -64,11 +67,14 @@ void l2_guest_code(void)
>         vmcall();
>         rdmsr_gs_base(); /* intercepted */
>  
> +       /* TSC scaling */
> +       vmcall();
> +
>         /* Done, exit to L1 and never come back.  */
>         vmcall();
>  }
>  
> -void guest_code(struct vmx_pages *vmx_pages)
> +void guest_code(struct vmx_pages *vmx_pages, u64 test_flags)
>  {
>  #define L2_GUEST_STACK_SIZE 64
>         unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE];
> @@ -150,6 +156,18 @@ void guest_code(struct vmx_pages *vmx_pages)
>         GUEST_ASSERT(vmreadz(VM_EXIT_REASON) == EXIT_REASON_VMCALL);
>         GUEST_SYNC(11);
>  
> +       if (test_flags & HOST_HAS_TSC_SCALING) {
> +               GUEST_ASSERT((rdmsr(MSR_IA32_VMX_PROCBASED_CTLS2) >> 32) &
> +                            SECONDARY_EXEC_TSC_SCALING);
> +               /* Try enabling TSC scaling */
> +               vmwrite(SECONDARY_VM_EXEC_CONTROL, vmreadz(SECONDARY_VM_EXEC_CONTROL) |
> +                       SECONDARY_EXEC_TSC_SCALING);
> +               vmwrite(TSC_MULTIPLIER, 1);
> +       }
> +       GUEST_ASSERT(!vmresume());
> +       GUEST_ASSERT(vmreadz(VM_EXIT_REASON) == EXIT_REASON_VMCALL);
> +       GUEST_SYNC(12);
> +
>         /* Try enlightened vmptrld with an incorrect GPA */
>         evmcs_vmptrld(0xdeadbeef, vmx_pages->enlightened_vmcs);
>         GUEST_ASSERT(vmlaunch());
> @@ -204,6 +222,7 @@ int main(int argc, char *argv[])
>         struct kvm_vm *vm;
>         struct kvm_run *run;
>         struct ucall uc;
> +       u64 test_flags = 0;
>         int stage;
>  
>         vm = vm_create_with_one_vcpu(&vcpu, guest_code);
> @@ -212,11 +231,19 @@ int main(int argc, char *argv[])
>         TEST_REQUIRE(kvm_has_cap(KVM_CAP_NESTED_STATE));
>         TEST_REQUIRE(kvm_has_cap(KVM_CAP_HYPERV_ENLIGHTENED_VMCS));
>  
> +       if ((kvm_get_feature_msr(MSR_IA32_VMX_PROCBASED_CTLS2) >> 32) &
> +           SECONDARY_EXEC_TSC_SCALING) {
> +               test_flags |= HOST_HAS_TSC_SCALING;
> +               pr_info("TSC scaling is supported, adding to test\n");
> +       } else {
> +               pr_info("TSC scaling is not supported\n");
> +       }
> +
>         vcpu_set_hv_cpuid(vcpu);
>         vcpu_enable_evmcs(vcpu);
>  
>         vcpu_alloc_vmx(vm, &vmx_pages_gva);
> -       vcpu_args_set(vcpu, 1, vmx_pages_gva);
> +       vcpu_args_set(vcpu, 2, vmx_pages_gva, test_flags);
>  
>         vm_init_descriptor_tables(vm);
>         vcpu_init_descriptor_tables(vcpu);

Reviewed-by: Maxim Levitsky <mlevitsk@...hat.com>

Best regards,
	Maxim Levitsky