Despite all but one patch being KVM cleanup, that one outlier is the
true catalyst for this series. The outlier, patch 3/11, removes an
optimization tweak from the __noclone macro that was added by commit
95272c29378e ("compiler-gcc: disable -ftracer for __noclone functions")
to workaround a compiler error in KVM's esoteric VMX assembly code.
Unbeknownst at the time, using the __optimize__ attribute causes GCC
to reset to -O2 optimization defaults, which has several unintended
side effects including dropping -fno-omit-frame-pointer and preventing
GCC from properly inlining function calls due to the functions having
incompatible optimization attributes.
Patches 1/11 and 2/11 fix the offending KVM code and eliminate its
usage of __noclone, allowing patch 3/11 to remove "no-tracer" from the
__noclone macro.
Patches 4/11 and beyond are a mix of cleanup, fixes and optimizations
for a variety of low hanging fruit that were (unsurprisingly) revealed
when revisiting KVM's inline assembly blob.
FYI, I cc'd everyone involved for all patches up until the -ftracer
revert, after that I limited the cc/to list to KVM folks.
Sean Christopherson (11):
KVM: VMX: Explicitly reference RCX as the vmx_vcpu pointer in asm
blobs
KVM: VMX: Move VM-Enter + VM-Exit handling to non-inline sub-routines
Revert "compiler-gcc: disable -ftracer for __noclone functions"
KVM: VMX: Modify only RSP when creating a placeholder for guest's RCX
KVM: VMX: Save RSI to an unused output in vmx_vcpu_run() asm blob
KVM: VMX: Manually load RDX in vmx_vcpu_run() asm blob
KVM: VMX: Let the compiler save/load RDX around VM-Enter
KVM: nVMX: Cache host_rsp on a per-VMCS basis
KVM: nVMX: Add eVMCS support to nested_vmx_check_vmentry_hw()
KVM: VMX: Add macros to handle HOST_RSP updates at VM-Enter
KVM: nVMX: Remove a rogue "rax" clobber from
nested_vmx_check_vmentry_hw()
arch/x86/kvm/Makefile | 2 +-
arch/x86/kvm/vmx/nested.c | 57 ++++---------
arch/x86/kvm/vmx/vmcs.h | 1 +
arch/x86/kvm/vmx/vmenter.S | 57 +++++++++++++
arch/x86/kvm/vmx/vmx.c | 127 +++++++++++++---------------
arch/x86/kvm/vmx/vmx.h | 30 ++++++-
include/linux/compiler_attributes.h | 8 +-
7 files changed, 164 insertions(+), 118 deletions(-)
create mode 100644 arch/x86/kvm/vmx/vmenter.S
--
2.19.2
