On Thu, Sep 6, 2018 at 6:32 AM, Liran Alon <liran.alon@xxxxxxxxxx> wrote:
> If CPU use both VPID and EPT, TLB entries populated by CPU are tagged
> with both EPTP and VPID. Therefore, if L1 uses EPT, L2 TLB entries
> are separated from L1 TLB entries by the EPTP tags as vmcs02 use
> EPTP02 while vmcs01 use EPTP01.
>
> Thus, we don't need to make sure that vmcs02->vpid != vmcs01->vpid.
> Therefore, we can just set vmcs02->vpid to vmcs12->vpid.
>
> Reviewed-by: Mihai Carabas <mihai.carabas@xxxxxxxxxx>
> Reviewed-by: Darren Kenny <darren.kenny@xxxxxxxxxx>
> Reviewed-by: Nikita Leshchenko <nikita.leshchenko@xxxxxxxxxx>
> Signed-off-by: Liran Alon <liran.alon@xxxxxxxxxx>
I suggested this back in July, but Paolo didn't like it. I still like it. :-)
Reviewed-by: Jim Mattson <jmattson@xxxxxxxxxx>
> ---
> arch/x86/kvm/vmx.c | 18 ++++++++++++++----
> 1 file changed, 14 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index b97e0c5ccb46..98faba65c24a 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -12018,10 +12018,20 @@ static void prepare_vmcs02_full(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
> vmcs_write64(GUEST_BNDCFGS, vmcs12->guest_bndcfgs);
>
> if (enable_vpid) {
> - if (nested_cpu_has_vpid(vmcs12) && vmx->nested.vpid02)
> - vmcs_write16(VIRTUAL_PROCESSOR_ID, vmx->nested.vpid02);
> - else
> - vmcs_write16(VIRTUAL_PROCESSOR_ID, vmx->vpid);
> + u16 vmcs02_vpid;
You could simplify the logic below if you initialize vmcs02_vpid to vmx->vpid.
BTW, when did we switch to compilation options that allow mid-block
declarations? Woohoo!
> + if (nested_cpu_has_vpid(vmcs12)) {
> + if (nested_cpu_has_ept(vmcs12))
> + vmcs02_vpid = vmcs12->virtual_processor_id;
> + else if (vmx->nested.vpid02)
> + vmcs02_vpid = vmx->nested.vpid02;
> + else
> + vmcs02_vpid = vmx->vpid;
> + } else {
> + vmcs02_vpid = vmx->vpid;
> + }
> +
> + vmcs_write16(VIRTUAL_PROCESSOR_ID, vmcs02_vpid);
> }
>
> /*
> --
> 2.16.1
>
