Messages in this thread | | | From | Paolo Bonzini <> | Subject | Re: [PATCH RFC 3/7] kvm: x86: XSAVE state and XFD MSRs context switch | Date | Mon, 8 Feb 2021 11:25:07 +0100 |
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On 07/02/21 16:42, Jing Liu wrote: > |In KVM, "guest_fpu" serves for any guest task working on this vcpu > during vmexit and vmenter. We provide a pre-allocated guest_fpu space > and entire "guest_fpu.state_mask" to avoid each dynamic features > detection on each vcpu task. Meanwhile, to ensure correctly > xsaves/xrstors guest state, set IA32_XFD as zero during vmexit and vmenter.|
Most guests will not need the whole xstate feature set. So perhaps you could set XFD to the host value | the guest value, trap #NM if the host XFD is zero, and possibly reflect the exception to the guest's XFD and XFD_ERR.
In addition, loading the guest XFD MSRs should use the MSR autoload feature (add_atomic_switch_msr).
Paolo
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