Messages in this thread | | | From | Paolo Bonzini <> | Date | Thu, 10 Aug 2023 02:01:29 +0200 | Subject | Re: [PATCH v5 04/19] KVM:x86: Refresh CPUID on write to guest MSR_IA32_XSS |
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On Wed, Aug 9, 2023 at 10:56 AM Yang, Weijiang <weijiang.yang@intel.com> wrote: > > I'm pretty sure I've advocated for the exact opposite in the past, i.e. argued > > that KVM's ABI is to not enforce ordering between KVM_SET_CPUID2 and KVM_SET_MSR. > > But this is becoming untenable, juggling the dependencies in KVM is complex and > > is going to result in a nasty bug at some point. > > > > For this series, lets just tighten the rules for XSS, i.e. drop the host_initated > > exemption. And in a parallel/separate series, try to do a wholesale cleanup of > > all the cases that essentially allow userspace to do KVM_SET_MSR before KVM_SET_CPUID2. > OK, will do it for this series and investigate for other MSRs. > Thanks!
Remember that, while the ordering between KVM_SET_CPUID2 and KVM_SET_MSR must be enforced(*), the host_initiated path must allow the default (generally 0) value.
Paolo
(*) this means that you should check guest_cpuid_has even if host_initiated == true.
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