linux-kernel - Re: [PATCH v3 2/5] KVM: x86: SVM: Update dump_vmcb with shadow stack save area additions

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Message-ID: <2de8bad3-cf18-466b-b6b5-79c399ebba2e@amd.com>
Date: Fri, 22 Aug 2025 15:57:37 -0500
From: Tom Lendacky <thomas.lendacky@....com>
To: John Allen <john.allen@....com>, kvm@...r.kernel.org,
 linux-kernel@...r.kernel.org, x86@...nel.org, seanjc@...gle.com,
 pbonzini@...hat.com, dave.hansen@...el.com
Cc: rick.p.edgecombe@...el.com, mlevitsk@...hat.com, weijiang.yang@...el.com,
 chao.gao@...el.com, bp@...en8.de, dave.hansen@...ux.intel.com,
 hpa@...or.com, mingo@...hat.com, tglx@...utronix.de
Subject: Re: [PATCH v3 2/5] KVM: x86: SVM: Update dump_vmcb with shadow stack
 save area additions

On 8/6/25 15:45, John Allen wrote:
> Add shadow stack VMCB save area fields to dump_vmcb. Only include S_CET,
> SSP, and ISST_ADDR. Since there currently isn't support to decrypt and
> dump the SEV-ES save area, exclude PL0_SSP, PL1_SSP, PL2_SSP, PL3_SSP,
> and U_CET which are only inlcuded in the SEV-ES save area.

There has been a recent patch series that can decrypt and dump VMSA
contents, so you could add those fields if you think they should be dumped.

Thanks,
Tom

> 
> Signed-off-by: John Allen <john.allen@....com>
> Reviewed-by: Maxim Levitsky <mlevitsk@...hat.com>
> ---
>  arch/x86/kvm/svm/svm.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index d4e27e70b926..a027d3c37181 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -3416,6 +3416,10 @@ static void dump_vmcb(struct kvm_vcpu *vcpu)
>  	       "rip:", save->rip, "rflags:", save->rflags);
>  	pr_err("%-15s %016llx %-13s %016llx\n",
>  	       "rsp:", save->rsp, "rax:", save->rax);
> +	pr_err("%-15s %016llx %-13s %016llx\n",
> +	       "s_cet:", save->s_cet, "ssp:", save->ssp);
> +	pr_err("%-15s %016llx\n",
> +	       "isst_addr:", save->isst_addr);
>  	pr_err("%-15s %016llx %-13s %016llx\n",
>  	       "star:", save01->star, "lstar:", save01->lstar);
>  	pr_err("%-15s %016llx %-13s %016llx\n",