From: Paolo Bonzini <pbonzini@redhat.com>
To: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
Wanpeng Li <wanpeng.li@hotmail.com>,
stable@vger.kernel.org
Subject: Re: [PATCH] KVM: x86: fix backward migration with async_PF
Date: Thu, 1 Feb 2018 14:33:10 -0500 [thread overview]
Message-ID: <c820ef8e-b352-ef28-4756-d6949f718ec0@redhat.com> (raw)
In-Reply-To: <20180201191040.GD26932@flask>
On 01/02/2018 14:10, Radim Krčmář wrote:
>>>
>> This check will break migration if the source guest and host both have
>> the recent kernels which support KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT, so
>> I am not sure about it. Otherwise, the patch is okay!
> Good point, breaking forward migration is worse than doing nothing.
>
> A compromise solution would be to drop the feature check from the
> hypervisor. Newer guests would work everywhere and there would be no
> change to old systems, so v4.13-v4.15 guests could at least upgrade.
>
> Slightly better than doing nothing, IMO,
Yes, I agree. Just removing the guest_kvm_cpuid_has should be fine.
Paolo
prev parent reply other threads:[~2018-02-01 19:33 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-01 17:50 [PATCH] KVM: x86: fix backward migration with async_PF Radim Krčmář
2018-02-01 18:09 ` Paolo Bonzini
2018-02-01 19:10 ` Radim Krčmář
2018-02-01 19:33 ` Paolo Bonzini [this message]
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