KVM's GPR caching logic is unconditionally emitted for all GPR accesses
(that go through the accessors), even when the register being accessed
is fixed and always available. This bloats KVM due to the instructions
needed to test and set the available/dirty bitmaps, and to conditionally
invoke the .cache_reg() callback. The latter is especially painful when
compiling with retpolines.
Eliminate the unnecessary overhead by:
- Adding dedicated accessors for every GPR
- Omitting the caching logic for GPRs that are always available
- Preventing use of the unoptimized versions for fixed accesses
The last patch is an opportunistic clean up of VMX, which has gradually
acquired a bad habit of sprinkling in direct access to GPRs.
Sean Christopherson (3):
KVM: x86: Omit caching logic for always-available GPRs
KVM: x86: Prevent use of kvm_register_{read,write}() with known GPRs
KVM: VMX: Use accessors for GPRs outside of dedicated caching logic
arch/x86/kvm/cpuid.c | 12 ++---
arch/x86/kvm/hyperv.c | 24 ++++-----
arch/x86/kvm/kvm_cache_regs.h | 73 +++++++++++++++++++++++----
arch/x86/kvm/svm.c | 34 ++++++-------
arch/x86/kvm/vmx/nested.c | 18 +++----
arch/x86/kvm/vmx/vmx.c | 14 +++---
arch/x86/kvm/x86.c | 93 +++++++++++++++++------------------
7 files changed, 159 insertions(+), 109 deletions(-)
--
2.21.0
