platform/kvm: map vdso and vvar into a guest address space

Right now, each vdso call triggers vmexit. VDSO and VVAR pages are
mapped with VM_IO and get_user_pages fails for such vma-s. KVM was not
able to handle this case up to the v4.8 kernel. This problem was fixed by
add6a0cd1c5ba ("KVM: MMU: try to fix up page faults before giving up").

For some unknown reasons, it still doesn't work in case of nested
virtualization.

Before:
BenchmarkKernelVDSO-6                   	  252519	      4598 ns/op
After:
BenchmarkKernelVDSO-6                   	34431957	        34.91 ns/op
PiperOrigin-RevId: 405715941

0 files changed, 0 insertions, 0 deletions