KVM: nVMX: optimize prepare_vmcs02{,_full} for Enlightened VMCS case

Browse source

When Enlightened VMCS is in use by L1 hypervisor we can avoid vmwriting
VMCS fields which did not change.

Our first goal is to achieve minimal impact on traditional VMCS case so
we're not wrapping each vmwrite() with an if-changed checker. We also can't
utilize static keys as Enlightened VMCS usage is per-guest.

This patch implements the simpliest solution: checking fields in groups.
We skip single vmwrite() statements as doing the check will cost us
something even in non-evmcs case and the win is tiny. Unfortunately, this
makes prepare_vmcs02_full{,_full}() code Enlightened VMCS-dependent (and
a bit ugly).

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

...

This commit is contained in:

Vitaly Kuznetsov 2018-10-16 18:50:04 +02:00 • committed by Paolo Bonzini

parent b8bbab928f

commit c4ebd6295a

1 changed files with 65 additions and 53 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

116

arch/x86/kvm/vmx.c

View file