KVM: nSVM: Move VMRUN instruction retirement after entering guest mode

KVM: nSVM: Move VMRUN instruction retirement after entering guest mode

A successful VMRUN retires in guest mode and should be counted by the
PMU as a guest instruction. Move the call to
kvm_pmu_instruction_retired() after potentially entering guest mode,
such that VMRUN is counted correctly.

The PMU event will be matched against L2's CPL, but otherwise this does
not change the behavior in terms of guest vs. host, because KVM does
not virtualize Host-Only/Guest-Only PMC controls yet, so all
instructions are counted regardless of the vCPU's host/guest state. But
this change is needed for the incoming support for Host-Only/Guest-Only
controls to count VMRUN correctly.

Signed-off-by: Yosry Ahmed <yosry@kernel.org>
Link: https://patch.msgid.link/20260527234711.4175166-5-yosry@kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>