tree 99db1bc065832b2685bd5edb75cd7c1019011ead
parent 35cc7f971188366f5a5c0d5da1456bb38cef5da9
author Avi Kivity <avi@qumranet.com> 1176982124 +0300
committer Avi Kivity <avi@qumranet.com> 1178178750 +0300

KVM: VMX: Only save/restore MSR_K6_STAR if necessary

Intel hosts only support syscall/sysret in long more (and only if efer.sce
is enabled), so only reload the related MSR_K6_STAR if the guest will
actually be able to use it.

This reduces vmexit cost by about 500 cycles (6400 -> 5870) on my setup.

Signed-off-by: Avi Kivity <avi@qumranet.com>