linux-kernel - Re: Re: [PATCH] KVM: x86: Fix uninitialized eoi_exit_bitmap usage in vcpu_load_eoi

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Message-ID: <877dd9efpb.fsf@redhat.com>
Date:   Mon, 15 Nov 2021 14:00:48 +0100
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     黄乐 <huangle1@...com>,
        "pbonzini@...hat.com" <pbonzini@...hat.com>
Cc:     "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: Re: [PATCH] KVM: x86: Fix uninitialized eoi_exit_bitmap usage
 in vcpu_load_eoi_exitmap()

黄乐 <huangle1@...com> writes:

>> 黄乐 <huangle1@...com> writes:
>> 
>> > 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 stack,
>> > which would cause unexpected interrupt delivery/handling issues, e.g. an
>> > *old* linux kernel that relies on PIT to do clock calibration on KVM might
>> > randomly fail to boot.
>> >
>> > Fix it by passing ioapic_handled_vectors to load_eoi_exitmap() when Hyper-V
>> > context is not available.
>> >
>> > Signed-off-by: Huang Le <huangle1@...com>
>> 
>> Fixes: f2bc14b69c38 ("KVM: x86: hyper-v: Prepare to meet unallocated Hyper-V context")
>> Cc: stable@...r.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@...r.kernel.org' is just an indication for everyone who has
f2bc14b69c38 in his tree (5.12+) that there's a fix available.

-- 
Vitaly