KVM: x86: Omit caching logic for always-available GPRs

Browse source

Except for RSP and RIP, which are held in VMX's VMCS, GPRs are always
treated "available and dirtly" on both VMX and SVM, i.e. are
unconditionally loaded/saved immediately before/after VM-Enter/VM-Exit.

Eliminating the unnecessary caching code reduces the size of KVM by a
non-trivial amount, much of which comes from the most common code paths.
E.g. on x86_64, kvm_emulate_cpuid() is reduced from 342 to 182 bytes and
kvm_emulate_hypercall() from 1362 to 1143, with the total size of KVM
dropping by ~1000 bytes.  With CONFIG_RETPOLINE=y, the numbers are even
more pronounced, e.g.: 353->182, 1418->1172 and well over 2000 bytes.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

...

This commit is contained in:

Sean Christopherson 2019-04-30 10:36:17 -07:00 • committed by Paolo Bonzini

parent 0c55671f84

commit de3cd117ed

6 changed files with 105 additions and 80 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

12

arch/x86/kvm/cpuid.c

View file

24

arch/x86/kvm/hyperv.c

View file

32

arch/x86/kvm/kvm_cache_regs.h

View file

26

arch/x86/kvm/svm.c

View file

2

arch/x86/kvm/vmx/vmx.c

View file

89

arch/x86/kvm/x86.c

View file