diff options
| author | Paolo Bonzini <pbonzini@redhat.com> | 2018-08-22 19:59:33 +0200 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2018-10-17 00:30:02 +0200 |
| commit | 0e0a53c551317654e2d7885fdfd23299fee99b6b (patch) | |
| tree | e7c3d7c079231e99dacb2d303f44243b704fb3ea /arch/x86/kvm/vmx.c | |
| parent | f21dd494506ad002a5b6b32e50a5d4ccac6929fe (diff) | |
| download | linux-0e0a53c551317654e2d7885fdfd23299fee99b6b.tar.bz2 | |
kvm: x86: optimize dr6 restore
The quote from the comment almost says it all: we are currently zeroing
the guest dr6 in kvm_arch_vcpu_put, because do_debug expects it. However,
the host %dr6 is either:
- zero because the guest hasn't run after kvm_arch_vcpu_load
- written from vcpu->arch.dr6 by vcpu_enter_guest
- written by the guest and copied to vcpu->arch.dr6 by ->sync_dirty_debug_regs().
Therefore, we can skip the write if vcpu->arch.dr6 is already zero. We
may do extra useless writes if vcpu->arch.dr6 is nonzero but the guest
hasn't run; however that is less important for performance.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm/vmx.c')
0 files changed, 0 insertions, 0 deletions