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From: Ani Sinha <ani.sinha@nutanix.com>
To: Qemu-Devel <qemu-devel@nongnu.org>
Subject: TOPOEXT and CentOs 7 guests
Date: Wed, 16 Oct 2019 12:51:58 +0000	[thread overview]
Message-ID: <SN6PR02MB513583C0D0C43777B47910D1F1920@SN6PR02MB5135.namprd02.prod.outlook.com> (raw)

Hi :

I am looking at a patch where we disable TOPOEXT when -cpu host or -cpu max is passed to qemu :

if (cpu->max_features) {
   for (w = 0; w < FEATURE_WORDS; w++) {
     /* Override only features that weren't set explicitly
      * by the user.
      */
      env->features[w] |=
      x86_cpu_get_supported_feature_word(w, cpu->migratable) &
         ~env->user_features[w] & \
         ~feature_word_info[w].no_autoenable_flags;
    }
}

https://lists.nongnu.org/archive/html/qemu-devel/2018-08/msg01641.html

We are using a setup where we pass “kvm64” as the cpu model along with other hypervisor CPIUD capabilities as detected by libvirt to a centOS 7.7 guest and the guest is unable to boot. We are using a AMD EPYC platform and we have traced it down to TOPOEXT flag being the offending CPUID from the host CPU which is causing the issue. Does it makes sense to not enable this flag by default on all other guest CPU models as well except for EPYC and EPTC-IBPB?

Just looking at the code very recently and thought I’d get an opinion from the wiser qemu community.

Thanks
Ani

             reply	other threads:[~2019-10-16 12:53 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-16 12:51 Ani Sinha [this message]
2019-10-16 13:37 ` TOPOEXT and CentOs 7 guests Daniel P. Berrangé
  -- strict thread matches above, loose matches on Subject: below --
2019-10-16 12:48 Ani Sinha
2019-10-16 11:05 Ani Sinha

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