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 <redacted>
Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Reviewed-by: Andi Kleen <redacted>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Tested-by: Neelima Krishnan <redacted>

[...]

-- 
Eduardo