On 23/01/21 00:50, Sean Christopherson wrote:
This is effectively belated feedback on the SEV-ES series. My primary
interest is to revert the GPR dirty/available tracking, as it's pure
overhead for non-SEV-ES VMs, and even for SEV-ES I suspect the dirty
tracking is at best lost in the noise, and possibly even a net negative.
My original plan was to submit patches 1+3 as patch 1, taking a few
creative liberties with the GHCB spec to justify writing the GHCB GPRs
after every VMGEXIT. But, since KVM is effectively writing the GHCB GPRs
on every VMRUN, I feel confident in saying that my interpretation of the
spec has already been proven correct.
The SEV-ES changes are effectively compile tested only, but unless I've
overlooked a code path, patch 1 is a nop. Patch 3 definitely needs
testing.
Paolo, I'd really like to get patches 1 and 2 into 5.11, the code cost of
the dirty/available tracking is not trivial.
Sean Christopherson (3):
KVM: SVM: Unconditionally sync GPRs to GHCB on VMRUN of SEV-ES guest
KVM: x86: Revert "KVM: x86: Mark GPRs dirty when written"
KVM: SVM: Sync GPRs to the GHCB only after VMGEXIT
arch/x86/kvm/kvm_cache_regs.h | 51 +++++++++++++++++------------------
arch/x86/kvm/svm/sev.c | 14 +++++-----
arch/x86/kvm/svm/svm.h | 1 +
3 files changed, 34 insertions(+), 32 deletions(-)
Queued 1-2, thanks! Yes, these should be in 5.11.
Paolo
