Message-ID: <1513169674.19417.188.camel@linuxfoundation.org>
Subject: Re: [PATCH 1/2] KVM: x86: fix APIC page invalidation
From: Richard Purdie <richard.purdie@linuxfoundation.org>
To: Radim =?UTF-8?Q?Kr=C4=8Dm=C3=A1=C5=99?= <rkrcmar@redhat.com>,
        Fabian =?ISO-8859-1?Q?Gr=FCnbichler?= 
        <f.gruenbichler@proxmox.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, kvm@vger.kernel.org,
        Paolo Bonzini <pbonzini@redhat.com>,
        Andrea Arcangeli <aarcange@redhat.com>,
        =?ISO-8859-1?Q?J=E9r=F4me?= Glisse <jglisse@redhat.com>,
        stable <stable@kernel.org>
Date: Wed, 13 Dec 2017 12:54:34 +0000
In-Reply-To: <20171130180546.4331-1-rkrcmar@redhat.com>
References: <20171130161933.GB1606@flask>
         <20171130180546.4331-1-rkrcmar@redhat.com>
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On Thu, 2017-11-30 at 19:05 +0100, Radim Krčmář wrote:
> Implementation of the unpinned APIC page didn't update the VMCS
> address
> cache when invalidation was done through range mmu notifiers.
> This became a problem when the page notifier was removed.
> 
> Re-introduce the arch-specific helper and call it from
> ...range_start.
> 
> Fixes: 38b9917350cb ("kvm: vmx: Implement set_apic_access_page_addr")
> Fixes: 369ea8242c0f ("mm/rmap: update to new mmu_notifier semantic
> v2")
> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
> ---
>  arch/x86/include/asm/kvm_host.h |  3 +++
>  arch/x86/kvm/x86.c              | 14 ++++++++++++++
>  virt/kvm/kvm_main.c             |  8 ++++++++
>  3 files changed, 25 insertions(+)

Thanks for this. I've been chasing APIC related hangs booting images
with qemu-system-x86_64 on 4.13 and 4.14 host kernels where the guest
doesn't have x2apic enabled.

I can confirm this fixes issues the Yocto Project automated testing
infrastructure was seeing.

I'd like to add support for backporting this in stable.

Tested-by: Richard Purdie <richard.purdie@linuxfoundation.org>

Cheers,

Richard