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

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Date:   Tue, 12 May 2020 21:03:36 +0000
From:   Dexuan Cui <decui@...rosoft.com>
To:     vkuznets <vkuznets@...hat.com>,
        "linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>
CC:     Wei Liu <wei.liu@...nel.org>, "x86@...nel.org" <x86@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        Michael Kelley <mikelley@...rosoft.com>,
        Tianyu Lan <Tianyu.Lan@...rosoft.com>
Subject: RE: [PATCH] x86/hyperv: Properly suspend/resume reenlightenment
 notifications

> From: Vitaly Kuznetsov <vkuznets@...hat.com>
> Sent: Tuesday, May 12, 2020 9:02 AM
> To: linux-hyperv@...r.kernel.org
> Cc: 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: [PATCH] x86/hyperv: Properly suspend/resume reenlightenment
> notifications
> 
> 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>
> ---

Looks good to me. Thanks!

Reviewed-by: Dexuan Cui <decui@...rosoft.com>