Messages in this thread | | | Date | Tue, 6 Jul 2021 15:51:27 -0700 | From | Pawan Gupta <> | Subject | Re: [PATCH 4/4] x86/tsx: Add cmdline tsx=fake to not clear CPUID bits RTM and HLE |
| |
On 06.07.2021 17:19, Eduardo Habkost wrote: >On Tue, Jul 6, 2021 at 5:15 PM Pawan Gupta ><pawan.kumar.gupta@linux.intel.com> wrote: >> >> On 06.07.2021 15:52, Eduardo Habkost wrote: >> >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? >> >> Yes, the global option is unnecessary and this patch was dropped in v2. > >Was the behaviour this patch originally tried to fix changed in v2 as >well? Is it going to be possible to resume a HLE=1,RTM=1 VM on a >TSX_FORCE_ABORT=1 host with no extra kernel command line options >needed?
The problem it tried to solve is still present, but the global switch was thought to be unnecessary. I see that Paolo has some suggestions to fix this in the userspace.
Thanks, Pawan
| |