On 12/13/23 14:49, Borislav Petkov wrote:
On Wed, Dec 13, 2023 at 02:40:24PM +0100, Paolo Bonzini wrote:
Why are they dead code? X86_FEATURE_SEV_SNP is set automatically based on
CPUID, therefore patch 5 is a performance improvement on all processors that
support SEV-SNP. This is independent of whether KVM can create SEV-SNP
guests or not.
No, it is not. This CPUID bit means:
"RMP table can be enabled to protect memory even from hypervisor."
Without the SNP host patches, it is dead code.
- if ((ia32_cap & ARCH_CAP_IBRS_ALL) || cpu_has(c, X86_FEATURE_AUTOIBRS)) {
+ if ((ia32_cap & ARCH_CAP_IBRS_ALL) ||
+ (cpu_has(c, X86_FEATURE_AUTOIBRS) &&
+ !cpu_feature_enabled(X86_FEATURE_SEV_SNP))) {
Surely we can agree that cpu_feature_enabled(X86_FEATURE_SEV_SNP) has nothing
to do with SEV-SNP host patches being present? And that therefore retpolines
are preferred even without any SEV-SNP support in KVM?
And can we agree that "Acked-by" means "feel free and take it if you wish,
I don't care enough to merge it through my tree or provide a topic branch"?
I'm asking because I'm not sure if we agree on these two things, but they
really seem basic to me?
Paolo
And regardless, arch/x86/kvm/ patches go through the kvm tree. The rest
of arch/x86/ through the tip tree. We've been over this a bunch of times
already.
If you don't agree with this split, let's discuss it offlist with all
tip and kvm maintainers, reach an agreement who picks up what and to put
an end to this nonsense.
Thx.
