Re: [PATCH v3] x86/vmx: save guest non-register state in hvm_hw_cpu

[Tamas K Lengyel <tamas.k.lengyel@xxxxxxxxx>]

On Mon, Mar 21, 2022, 12:41 PM Jan Beulich <jbeulich@xxxxxxxx> wrote:

On 21.03.2022 17:26, Tamas K Lengyel wrote:
> During VM forking and resetting a failed vmentry has been observed due
> to the guest non-register state going out-of-sync with the guest register
> state. For example, a VM fork reset right after a STI instruction can trigger
> the failed entry. This is due to the guest non-register state not being saved
> from the parent VM, thus the reset operation only copies the register state.
>
> Fix this by including the guest non-register state in hvm_hw_cpu so that when
> its copied from the parent VM the vCPU state remains in sync.
>
> SVM is not currently wired-in as VM forking is VMX only and saving non-register
> state during normal save/restore/migration operation hasn't been needed. If
> deemed necessary in the future it can be wired in by adding a svm-substructure
> to hvm_hw_cpu.
>
> Signed-off-by: Tamas K Lengyel <tamas.lengyel@xxxxxxxxx>

Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>

Thanks, will send v4 shortly, will need a couple fixes still.

Tamas