linux-kernel - Re: [PATCH v2 13/49] KVM: selftests: Fix a bad TEST

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Message-ID: <5d27e799daf7677a8d26c7769a5d24b6d3459aa2.camel@redhat.com>
Date: Thu, 04 Jul 2024 21:17:22 -0400
From: Maxim Levitsky <mlevitsk@...hat.com>
To: Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini
 <pbonzini@...hat.com>,  Vitaly Kuznetsov <vkuznets@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org, Hou Wenlong
 <houwenlong.hwl@...group.com>, Kechen Lu <kechenl@...dia.com>, Oliver Upton
 <oliver.upton@...ux.dev>, Binbin Wu <binbin.wu@...ux.intel.com>, Yang
 Weijiang <weijiang.yang@...el.com>, Robert Hoo <robert.hoo.linux@...il.com>
Subject: Re: [PATCH v2 13/49] KVM: selftests: Fix a bad TEST_REQUIRE() in
 x86's KVM PV test

On Fri, 2024-05-17 at 10:38 -0700, Sean Christopherson wrote:
> Actually check for KVM support for disabling HLT-exiting instead of
> effectively checking that KVM_CAP_X86_DISABLE_EXITS is #defined to a
> non-zero value, and convert the TEST_REQUIRE() to a simple return so
> that only the sub-test is skipped if HLT-exiting is mandatory.
> 
> The goof has likely gone unnoticed because all x86 CPUs support disabling
> HLT-exiting, only systems with the opt-in mitigate_smt_rsb KVM module
> param disallow HLT-exiting.
> 
> Signed-off-by: Sean Christopherson <seanjc@...gle.com>
> ---
>  tools/testing/selftests/kvm/x86_64/kvm_pv_test.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/testing/selftests/kvm/x86_64/kvm_pv_test.c b/tools/testing/selftests/kvm/x86_64/kvm_pv_test.c
> index 78878b3a2725..2aee93108a54 100644
> --- a/tools/testing/selftests/kvm/x86_64/kvm_pv_test.c
> +++ b/tools/testing/selftests/kvm/x86_64/kvm_pv_test.c
> @@ -140,10 +140,11 @@ static void test_pv_unhalt(void)
>  	struct kvm_cpuid_entry2 *ent;
>  	u32 kvm_sig_old;
>  
> +	if (!(kvm_check_cap(KVM_CAP_X86_DISABLE_EXITS) & KVM_X86_DISABLE_EXITS_HLT))
> +		return;
> +
>  	pr_info("testing KVM_FEATURE_PV_UNHALT\n");
>  
> -	TEST_REQUIRE(KVM_CAP_X86_DISABLE_EXITS);
> -
>  	/* KVM_PV_UNHALT test */
>  	vm = vm_create_with_one_vcpu(&vcpu, guest_main);
>  	vcpu_set_cpuid_feature(vcpu, X86_FEATURE_KVM_PV_UNHALT);

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

Best regards,
	Maxim Levitsky