Messages in this thread | ![/](/images/icornerl.gif) | | Date | Fri, 21 Aug 2020 09:47:43 +0200 | From | Borislav Petkov <> | Subject | Re: [PATCH] x86/entry/64: Disallow RDPID in paranoid entry if KVM is enabled |
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On Thu, Aug 20, 2020 at 07:50:50PM -0700, Sean Christopherson wrote: > + * Disallow RDPID if KVM is enabled as it may consume a guest's TSC_AUX > + * if an NMI arrives in KVM's run loop. KVM loads guest's TSC_AUX on > + * VM-Enter and may not restore the host's value until the CPU returns > + * to userspace, i.e. KVM depends on the kernel not using TSC_AUX. > */
And frankly, this is really unfair. The kernel should be able to use any MSR. IOW, KVM needs to be fixed here. I'm sure it context-switches other MSRs so one more MSR is not a big deal.
-- Regards/Gruss, Boris.
https://people.kernel.org/tglx/notes-about-netiquette
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