Messages in this thread | | | Date | Tue, 15 Nov 2022 17:10:50 -0600 | From | Kim Phillips <> | Subject | Re: [PATCH 1/3] x86/cpufeatures: Add support for cpuid leaf 80000021/EAX (FeatureExt2Eax) |
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On 11/4/22 4:48 PM, Borislav Petkov wrote: > On Fri, Nov 04, 2022 at 04:36:49PM -0500, Kim Phillips wrote: >> AMD Zen4 processors advertise features in this leaf. >> Add the leaf and its Automatic IBRS feature bit. >> >> Note: New whole leaf (vs a bit) due to propagation via KVM >> later in this series. > > No, not a separate leaf - use scattered.c > > For an example what to do for KVM, see > > https://lore.kernel.org/r/20221103025030.78371-1-jiaxi.chen@linux.intel.com
That adds features that are mutually exclusive between kvm and the host kernel, unlike AUTOIBRS.
When trying to wire up a scattered host AUTOIBRS version up to kvm, I couldn't get past all the reverse_cpuid_check() BUILD_BUGs demanding exclusivity between h/w and "Linux" (s/w) FEATUREs.
Is there an example of a scattered feature that gets both its boot_cpu_has() and guest_cpuid_has() satisfied in the same build?
If not, I'll resubmit like this original submission - AUTOIBRS in a separate h/w leaf.
Thanks,
Kim
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