>-----Original Message----- >From: Li, Xiaoyao <xiaoyao...@intel.com> >Sent: Friday, July 15, 2022 9:14 AM >To: Paolo Bonzini <pbonz...@redhat.com>; Duan, Zhenzhong ><zhenzhong.d...@intel.com>; qemu-devel@nongnu.org >Cc: ehabk...@redhat.com; Ma, XiangfeiX <xiangfeix...@intel.com>; >Christopherson,, Sean <sea...@google.com> >Subject: Re: [PATCH v2] target/i386: Restore TSX features with taa-no > >On 7/14/2022 3:59 PM, Paolo Bonzini wrote: >> On 7/14/22 07:36, Zhenzhong Duan wrote: >>> On ICX-2S2 host, when run L2 guest with both L1/L2 using >>> Icelake-Server-v3 >>> or above, we got below warning: >>> >>> "warning: host doesn't support requested feature: MSR(10AH).taa-no >>> [bit 8]" >>> >>> This is because L1 KVM doesn't expose taa-no to L2 if RTM is >>> disabled, then starting L2 qemu triggers the warning. >>> >>> Fix it by restoring TSX features in Icelake-Server-v3, which may also >>> help guest performance if host isn't susceptible to TSX Async Abort >>> (TAA) vulnerabilities. >>> >>> Fixes: d965dc35592d ("target/i386: Add ARCH_CAPABILITIES related bits >>> into Icelake-Server CPU model") >>> Tested-by: Xiangfei Ma <xiangfeix...@intel.com> >>> Signed-off-by: Zhenzhong Duan <zhenzhong.d...@intel.com> >>> --- >>> v2: Rewrite commit message >> >> Why wouldn't the fix be (in an Icelake-Server-v4 model) to remove taa-no? > >Production Icelake silicon should have the taa-no set, that's the reason taa-no >was added in v3 model. > >When taa-no presents, it's safe to bring TSX features back. > >I'm wondering if we need a new version (v7) for this change.
Ping. Any further suggestion on which way to go ahead? Thanks Zhenzhong