From:   Vitaly Kuznetsov <vkuznets@redhat.com>
To:     =?utf-8?B?6buE5LmQ?= <huangle1@jd.com>,
        "pbonzini@redhat.com" <pbonzini@redhat.com>
Cc:     "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: Re: [PATCH] KVM: x86: Fix uninitialized eoi_exit_bitmap usage
 in vcpu_load_eoi_exitmap()
In-Reply-To: <567b276444f841519e42c91f43f5acd7@jd.com>
References: <567b276444f841519e42c91f43f5acd7@jd.com>
Date:   Mon, 15 Nov 2021 14:00:48 +0100
Message-ID: <877dd9efpb.fsf@redhat.com>
MIME-Version: 1.0
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=E9=BB=84=E4=B9=90 <huangle1@jd.com> writes:

>> =E9=BB=84=E4=B9=90 <huangle1@jd.com> writes:
>>=20
>> > In vcpu_load_eoi_exitmap(), currently the eoi_exit_bitmap[4] array is
>> > initialized only when Hyper-V context is available, in other path it is
>> > just passed to kvm_x86_ops.load_eoi_exitmap() directly from on the sta=
ck,
>> > which would cause unexpected interrupt delivery/handling issues, e.g. =
an
>> > *old* linux kernel that relies on PIT to do clock calibration on KVM m=
ight
>> > randomly fail to boot.
>> >
>> > Fix it by passing ioapic_handled_vectors to load_eoi_exitmap() when Hy=
per-V
>> > context is not available.
>> >
>> > Signed-off-by: Huang Le <huangle1@jd.com>
>>=20
>> Fixes: f2bc14b69c38 ("KVM: x86: hyper-v: Prepare to meet unallocated Hyp=
er-V context")
>> Cc: stable@vger.kernel.org
>
> Commit f2bc14b69c38 is not in stable tree I guess, it was merged in from =
5.12,
> do we still need Cc this patch to stable maintainers?
>

There are multiple stable trees, one for each major release. Not all of
them are still supported but you don't need to care about it, 'Cc:
stable@vger.kernel.org' is just an indication for everyone who has
f2bc14b69c38 in his tree (5.12+) that there's a fix available.

--=20
Vitaly