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Re: [PATCH 3/3] x86: Expose Automatic IBRS to guests
- To: Alejandro Vallejo <alejandro.vallejo@xxxxxxxxx>, Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxxx>
- From: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
- Date: Fri, 26 May 2023 18:39:38 +0100
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- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 26/05/2023 4:00 pm, Alejandro Vallejo wrote:
> Expose AutoIBRS to HVM guests, because they can just use it. Make sure
> writes to EFER:AIBRSE are gated on the feature being exposed. Also hide
> EFER:AIBRSE from PV guests as they have no say in the matter.
>
> Signed-off-by: Alejandro Vallejo <alejandro.vallejo@xxxxxxxxx>
It's worth saying "EFER is fully switched by VMRUN, so there's nothing
further for Xen to do in order for HVM guests to use AutoIBRS".
We can in principle support AutoIBRS on PV guests, but it's fine not to
for now.
This patch probably wants reordering to #2, because it is entirely
independent of what Xen is doing with AutoIBRS for spec safety.
It will need a minor rebase over the bit name shortening, but otherwise
Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
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