linux-kernel - Re: [PATCH] x86/hyperv: Properly suspend/resume reenlightenment notifications

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Message-ID: <20200513150153.2xi4v2ekpv7zmofo@liuwe-devbox-debian-v2.j3c5onc20sse1dnehy4noqpfcg.zx.internal.cloudapp.net>
Date:   Wed, 13 May 2020 15:01:53 +0000
From:   Wei Liu <wei.liu@...nel.org>
To:     Vitaly Kuznetsov <vkuznets@...hat.com>
Cc:     linux-hyperv@...r.kernel.org, Wei Liu <wei.liu@...nel.org>,
        x86@...nel.org, linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        Michael Kelley <mikelley@...rosoft.com>,
        Dexuan Cui <decui@...rosoft.com>,
        Tianyu Lan <Tianyu.Lan@...rosoft.com>
Subject: Re: [PATCH] x86/hyperv: Properly suspend/resume reenlightenment
 notifications

On Tue, May 12, 2020 at 06:01:53PM +0200, Vitaly Kuznetsov wrote:
> Errors during hibernation with reenlightenment notifications enabled were
> reported:
> 
>  [   51.730435] PM: hibernation entry
>  [   51.737435] PM: Syncing filesystems ...
>  ...
>  [   54.102216] Disabling non-boot CPUs ...
>  [   54.106633] smpboot: CPU 1 is now offline
>  [   54.110006] unchecked MSR access error: WRMSR to 0x40000106 (tried to
>      write 0x47c72780000100ee) at rIP: 0xffffffff90062f24
>      native_write_msr+0x4/0x20)
>  [   54.110006] Call Trace:
>  [   54.110006]  hv_cpu_die+0xd9/0xf0
>  ...
> 
> Normally, hv_cpu_die() just reassigns reenlightenment notifications to some
> other CPU when the CPU receiving them goes offline. Upon hibernation, there
> is no other CPU which is still online so cpumask_any_but(cpu_online_mask)
> returns >= nr_cpu_ids and using it as hv_vp_index index is incorrect.
> Disable the feature when cpumask_any_but() fails.
> 
> Also, as we now disable reenlightenment notifications upon hibernation we
> need to restore them on resume. Check if hv_reenlightenment_cb was
> previously set and restore from hv_resume().
> 
> Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>

Applied to hyperv-fixes.

Thank you all.

Wei.