Messages in this thread | | | Date | Tue, 6 Jul 2021 15:52:33 -0400 | From | Eduardo Habkost <> | Subject | Re: [PATCH 4/4] x86/tsx: Add cmdline tsx=fake to not clear CPUID bits RTM and HLE |
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On Wed, Jun 09, 2021 at 02:14:39PM -0700, Pawan Gupta wrote: > On CPUs that deprecated TSX, clearing the enumeration bits CPUID.RTM and > CPUID.HLE may not be desirable in some corner cases. Like a saved guest > would refuse to resume if it was saved before the microcode update > that deprecated TSX.
Why is a global option necessary to allow those guests to be resumed? Why can't KVM_GET_SUPPORTED_CPUID always return the HLE and RTM bits as supported when the host CPU has them?
> > Add a cmdline option "tsx=fake" to not clear CPUID bits even when the > hardware always aborts TSX transactions. > > Suggested-by: Tony Luck <tony.luck@intel.com> > Suggested-by: Andi Kleen <ak@linux.intel.com> > Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> > Reviewed-by: Andi Kleen <ak@linux.intel.com> > Reviewed-by: Tony Luck <tony.luck@intel.com> > Tested-by: Neelima Krishnan <neelima.krishnan@intel.com> [...]
-- Eduardo
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