Re: [PATCH v3 07/27] KVM: VMX: Initialize VMCS FRED fields

[Xin Li]

On 10/22/2024 2:06 AM, Chao Gao wrote:
> > @@ -1503,6 +1503,18 @@ void vmx_vcpu_load_vmcs(struct kvm_vcpu *vcpu, int cpu,
> > 				    (unsigned long)(cpu_entry_stack(cpu) + 1));
> > 		}
> >
> > +		/* Per-CPU FRED MSRs */
> > +		if (kvm_cpu_cap_has(X86_FEATURE_FRED)) {
> > +#ifdef CONFIG_X86_64
> > +			vmcs_write64(HOST_IA32_FRED_RSP1, __this_cpu_ist_top_va(DB));
> > +			vmcs_write64(HOST_IA32_FRED_RSP2, __this_cpu_ist_top_va(NMI));
> > +			vmcs_write64(HOST_IA32_FRED_RSP3, __this_cpu_ist_top_va(DF));
> > +#endif
> > +			vmcs_write64(HOST_IA32_FRED_SSP1, 0);
> > +			vmcs_write64(HOST_IA32_FRED_SSP2, 0);
> > +			vmcs_write64(HOST_IA32_FRED_SSP3, 0);
>
> Given SSP[1-3] are constant for now, how about asserting that host SSP[1-3] are
> all zeros when KVM is loaded and moving their writes to vmx_set_constant_host_state()?

I like the idea :)