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Message-ID: <ad800a830dab3cdefc28e30aa0b59fa5b4ba0211.camel@infradead.org>
Subject: Re: [PATCH v10 16/19] KVM: xen: split up kvm_xen_set_evtchn_fast()
From:   David Woodhouse <dwmw2@infradead.org>
To:     Paul Durrant <paul@xen.org>, Paolo Bonzini <pbonzini@redhat.com>,
        Jonathan Corbet <corbet@lwn.net>,
        Sean Christopherson <seanjc@google.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>, x86@kernel.org,
        "H. Peter Anvin" <hpa@zytor.com>, Shuah Khan <shuah@kernel.org>,
        kvm@vger.kernel.org, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org
Date:   Thu, 14 Dec 2023 14:20:27 +0000
In-Reply-To: <e22e354305d853d72039c7e12b166410de3f63c9.camel@infradead.org>
References: <20231204144334.910-1-paul@xen.org>
         <20231204144334.910-17-paul@xen.org>
         <e22e354305d853d72039c7e12b166410de3f63c9.camel@infradead.org>
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On Thu, 2023-12-14 at 14:00 +0000, David Woodhouse wrote:
>=20
> > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0if (IS_ENABLED(CONFIG_64BIT)=
 && kvm->arch.xen.long_mode) {
> > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0struct vcpu_info *vcpu_info =3D gpc->khva;
> > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0u32 port_word_bit =3D port / 32;
>=20
> Shouldn't that one be /64, and the compat one be /32?

I think the reason the test failed to spot this for you is because...

#define EVTCHN_TEST1 15
#define EVTCHN_TEST2 66
#define EVTCHN_TIMER 13

... it doesn't actually use any port numbers where the bit# differs for
32-bit vs. 64-bit.

If you change EVTCHN_TIMER to something like 50, I bet it'll fail (as
it should).

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