linux-kernel - Re: [PATCH V6 4/4] KVM: selftests: Add test for configure of x86 APIC bus frequency

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Message-ID: <Zkt2gNFxC0MHyIRb@google.com>
Date: Mon, 20 May 2024 09:12:48 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Reinette Chatre <reinette.chatre@...el.com>
Cc: isaku.yamahata@...el.com, pbonzini@...hat.com, erdemaktas@...gle.com, 
	vkuznets@...hat.com, vannapurve@...gle.com, jmattson@...gle.com, 
	mlevitsk@...hat.com, xiaoyao.li@...el.com, chao.gao@...el.com, 
	rick.p.edgecombe@...el.com, yuan.yao@...el.com, kvm@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH V6 4/4] KVM: selftests: Add test for configure of x86 APIC
 bus frequency

On Mon, May 20, 2024, Reinette Chatre wrote:
> On 5/6/2024 11:35 AM, Reinette Chatre wrote:
> > diff --git a/tools/testing/selftests/kvm/x86_64/apic_bus_clock_test.c b/tools/testing/selftests/kvm/x86_64/apic_bus_clock_test.c
> > new file mode 100644
> > index 000000000000..56eb686144c6
> > --- /dev/null
> > +++ b/tools/testing/selftests/kvm/x86_64/apic_bus_clock_test.c
> > @@ -0,0 +1,166 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * Test configure of APIC bus frequency.
> > + *
> > + * Copyright (c) 2024 Intel Corporation
> > + *
> > + * To verify if the APIC bus frequency can be configured this, test starts
> > + * by setting the TSC frequency in KVM, and then:
> > + * For every APIC timer frequency supported:
> > + * * In the guest:
> > + * * * Start the APIC timer by programming the APIC TMICT (initial count
> > + *       register) to the largest value possible to guarantee that it will
> > + *       not expire during the test,
> > + * * * Wait for a known duration based on previously set TSC frequency,
> > + * * * Stop the timer and read the APIC TMCCT (current count) register to
> > + *       determine the count at that time (TMCCT is loaded from TMICT when
> > + *       TMICT is programmed and then starts counting down).
> > + * * In the host:
> > + * * * Determine if the APIC counts close to configured APIC bus frequency
> > + *     while taking into account how the APIC timer frequency was modified
> > + *     using the APIC TDCR (divide configuration register).
> > + */
> > +#define _GNU_SOURCE /* for program_invocation_short_name */
> 
> As reported in [1] this #define is no longer needed after commit 730cfa45b5f4
> ("KVM: selftests: Define _GNU_SOURCE for all selftests code"). This will be
> fixed in next version of this series.

Don't worry about sending another version just for this, I can clean this up when
applying.