Re: [PATCH 6/7] KVM: SVM: Dump FRED context in dump_vmcb()

[Sean Christopherson <seanjc@google.com>]

On Thu, Jan 29, 2026, Shivansh Dhiman wrote:
> Add fields related to FRED to dump_vmcb() to dump FRED context.
> 
> Signed-off-by: Shivansh Dhiman <shivansh.dhiman@amd.com>
> ---
>  arch/x86/kvm/svm/svm.c | 39 +++++++++++++++++++++++++++++++++++++++
>  1 file changed, 39 insertions(+)
> 
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index 374589784206..954df4eae90e 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -3319,6 +3319,8 @@ static void dump_vmcb(struct kvm_vcpu *vcpu)
>  	pr_err("%-20s%016llx\n", "vmsa_pa:", control->vmsa_pa);
>  	pr_err("%-20s%016llx\n", "allowed_sev_features:", control->allowed_sev_features);
>  	pr_err("%-20s%016llx\n", "guest_sev_features:", control->guest_sev_features);
> +	pr_err("%-20s%016llx\n", "exit_int_data:", control->exit_int_data);
> +	pr_err("%-20s%016llx\n", "event_inj_data:", control->event_inj_data);
>  
>  	if (sev_es_guest(vcpu->kvm)) {
>  		save = sev_decrypt_vmsa(vcpu);
> @@ -3434,6 +3436,25 @@ static void dump_vmcb(struct kvm_vcpu *vcpu)
>  		       "r14:", vmsa->r14, "r15:", vmsa->r15);
>  		pr_err("%-15s %016llx %-13s %016llx\n",
>  		       "xcr0:", vmsa->xcr0, "xss:", vmsa->xss);
> +
> +		pr_err("%-27s %d %-18s%016llx\n",
> +		       "is_fred_enabled:", is_fred_enabled(vcpu),
> +		       "guest_evntinjdata:", vmsa->guest_event_inj_data);
> +		pr_err("%-12s %016llx %-18s%016llx\n",
> +		       "fred_config:", vmsa->fred_config,
> +		       "guest_exitintdata:", vmsa->guest_exit_int_data);
> +		pr_err("%-15s %016llx %-13s %016llx\n",
> +		       "fred_rsp0:", vmsa->fred_rsp0,
> +		       "fred_rsp1:", vmsa->fred_rsp1);
> +		pr_err("%-15s %016llx %-13s %016llx\n",
> +		       "fred_rsp2:", vmsa->fred_rsp2,
> +		       "fred_rsp3:", vmsa->fred_rsp3);
> +		pr_err("%-15s %016llx %-13s %016llx\n",
> +		       "fred_stklvls:", vmsa->fred_stklvls,
> +		       "fred_ssp1:", vmsa->fred_ssp1);
> +		pr_err("%-15s %016llx %-13s %016llx\n",
> +		       "fred_ssp2:", vmsa->fred_ssp2,
> +		       "fred_ssp3:", vmsa->fred_ssp3);
>  	} else {
>  		pr_err("%-15s %016llx %-13s %016lx\n",
>  		       "rax:", save->rax, "rbx:",
> @@ -3461,6 +3482,24 @@ static void dump_vmcb(struct kvm_vcpu *vcpu)
>  		       "r14:", vcpu->arch.regs[VCPU_REGS_R14],
>  		       "r15:", vcpu->arch.regs[VCPU_REGS_R15]);
>  #endif
> +		pr_err("%-26s %d %-18s %016llx\n",
> +		       "is_fred_enabled:", is_fred_enabled(vcpu),
> +		       "guest_evntinjdata:", save->guest_event_inj_data);
> +		pr_err("%-12s%016llx %-18s%016llx\n",
> +		       "fred_config:", save->fred_config,
> +		       "guest_exitintdata:", save->guest_exit_int_data);
> +		pr_err("%-15s %016llx %-13s %016llx\n",
> +		       "fred_rsp0:", save->fred_rsp0,
> +		       "fred_rsp1:", save->fred_rsp1);
> +		pr_err("%-15s %016llx %-13s %016llx\n",
> +		       "fred_rsp2:", save->fred_rsp2,
> +		       "fred_rsp3:", save->fred_rsp3);
> +		pr_err("%-15s %016llx %-13s %016llx\n",
> +		       "fred_stklvls:", save->fred_stklvls,
> +		       "fred_ssp1:", save->fred_ssp1);
> +		pr_err("%-15s %016llx %-13s %016llx\n",
> +		       "fred_ssp2:", save->fred_ssp2,
> +		       "fred_ssp3:", save->fred_ssp3);

These should all be gated on guest_cpu_cap_has(X86_FEATURE_FRED).  Just because
KVM can read and print garbage doesn't mean it should.