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Re: [Qemu-devel] Help debugging a regression in KVM Module
From: |
Radim Krčmář |
Subject: |
Re: [Qemu-devel] Help debugging a regression in KVM Module |
Date: |
Tue, 18 Aug 2015 08:25:23 -0700 |
2015-08-18 16:54+0200, Peter Lieven:
> After some experiments I was able to find out the bad commit that introduced
> the regression:
>
> commit f30ebc312ca9def25650b4e1d01cdb425c310dca
> Author: Radim Krčmář <address@hidden>
> Date: Thu Oct 30 15:06:47 2014 +0100
>
> It seems that this optimisation is not working reliabliy after live
> migration. I can't reproduce if
> I take a 3.19 kernel and revert this single commit.
Hello, this bug has gone unnoticed for a long time so it is fixed only
since v4.1 (and v3.19.stable was dead at that point).
commit b6ac069532218027f2991cba01d7a72a200688b0
Author: Radim Krčmář <address@hidden>
Date: Fri Jun 5 20:57:41 2015 +0200
KVM: x86: fix lapic.timer_mode on restore
lapic.timer_mode was not properly initialized after migration, which
broke few useful things, like login, by making every sleep eternal.
Fix this by calling apic_update_lvtt in kvm_apic_post_state_restore.
There are other slowpaths that update lvtt, so this patch makes sure
something similar doesn't happen again by calling apic_update_lvtt
after every modification.
Cc: address@hidden
Fixes: f30ebc312ca9 ("KVM: x86: optimize some accesses to LVTT and SPIV")
Signed-off-by: Radim Krčmář <address@hidden>
Signed-off-by: Marcelo Tosatti <address@hidden>