Re: [PATCH] Fix sysenter migration issue on AMD CPUs

[Avi Kivity <avi@redhat.com>]

On 08/21/2009 02:58 PM, Andre Przywara wrote:
> To enable cross-vendor migration we use VMCB external variables to hold
> the full 64bit value of the SYSENTER MSRs, which get truncated to 32bit
> on AMD hardware. Since we didn't intercept these MSRs, these
> variables were only used in the emulation case, but were _always_ used
> for migration purposes. This worked fine for cross-vendor migration in
> compat mode, but did not work in pure legacy mode.
> To fix this we always intercept the SYSENTER MSRs and store the values
> both in the VMCB and the external variables. This works for all cases.
>
> Signed-off-by: Andre Przywara<andre.przywara@amd.com>
> ---
>   arch/x86/kvm/svm.c |    9 ++++-----
>   1 files changed, 4 insertions(+), 5 deletions(-)
>
> Hi Avi,
>
> this should fix the problem seen by Stephane and Thomas this week.
> Please revert 8b2f9d194288982d654c1afef491dfdf75ec1ba9 (your proposed fix,
> which broke cross-vendor migration) and apply this patch afterwards.
> It worked for me with both 32on32 and 32on64 migration both cross-vendor
> and between two AMD machines.
>    

Reverted and applied; thanks.

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