linux-kernel - Re: [PATCH v5 34/34] KVM: SVM: Provide support to launch and run an SEV-ES guest

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Message-ID: <d75a9f3e-0f8e-6a2d-b9c3-c4d12933553e@amd.com>
Date:   Wed, 16 Dec 2020 10:55:30 -0600
From:   Tom Lendacky <thomas.lendacky@....com>
To:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org, x86@...nel.org,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     Jim Mattson <jmattson@...gle.com>, Joerg Roedel <joro@...tes.org>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Borislav Petkov <bp@...en8.de>, Ingo Molnar <mingo@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Brijesh Singh <brijesh.singh@....com>
Subject: Re: [PATCH v5 34/34] KVM: SVM: Provide support to launch and run an
 SEV-ES guest

On 12/10/20 11:10 AM, Tom Lendacky wrote:
> From: Tom Lendacky <thomas.lendacky@....com>
>
> An SEV-ES guest is started by invoking a new SEV initialization ioctl,
> KVM_SEV_ES_INIT. This identifies the guest as an SEV-ES guest, which is
> used to drive the appropriate ASID allocation, VMSA encryption, etc.
>
> Before being able to run an SEV-ES vCPU, the vCPU VMSA must be encrypted
> and measured. This is done using the LAUNCH_UPDATE_VMSA command after all
> calls to LAUNCH_UPDATE_DATA have been performed, but before LAUNCH_MEASURE
> has been performed. In order to establish the encrypted VMSA, the current
> (traditional) VMSA and the GPRs are synced to the page that will hold the
> encrypted VMSA and then LAUNCH_UPDATE_VMSA is invoked. The vCPU is then
> marked as having protected guest state.
>
> Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
> ---
> +
> +	/* Sync registgers */
> +	save->rax = svm->vcpu.arch.regs[VCPU_REGS_RAX];
> +	save->rbx = svm->vcpu.arch.regs[VCPU_REGS_RBX];
> +	save->rcx = svm->vcpu.arch.regs[VCPU_REGS_RCX];
> +	save->rdx = svm->vcpu.arch.regs[VCPU_REGS_RDX];
> +	save->rsp = svm->vcpu.arch.regs[VCPU_REGS_RSP];
> +	save->rbp = svm->vcpu.arch.regs[VCPU_REGS_RBP];
> +	save->rsi = svm->vcpu.arch.regs[VCPU_REGS_RSI];
> +	save->rdi = svm->vcpu.arch.regs[VCPU_REGS_RDI];
> +	save->r8  = svm->vcpu.arch.regs[VCPU_REGS_R8];
> +	save->r9  = svm->vcpu.arch.regs[VCPU_REGS_R9];
> +	save->r10 = svm->vcpu.arch.regs[VCPU_REGS_R10];
> +	save->r11 = svm->vcpu.arch.regs[VCPU_REGS_R11];
> +	save->r12 = svm->vcpu.arch.regs[VCPU_REGS_R12];
> +	save->r13 = svm->vcpu.arch.regs[VCPU_REGS_R13];
> +	save->r14 = svm->vcpu.arch.regs[VCPU_REGS_R14];
> +	save->r15 = svm->vcpu.arch.regs[VCPU_REGS_R15];
> +	save->rip = svm->vcpu.arch.regs[VCPU_REGS_RIP];
> +

Paolo, I just noticed that a 32-bit build will fail because of R8-R15
references, sorry about that (I'm kind of surprised krobot hasn't
complained). This should take care of it:

---
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 4045de7f8f8b..84b3ee15f4ec 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -529,6 +529,7 @@ static int sev_es_sync_vmsa(struct vcpu_svm *svm)
 	save->rbp = svm->vcpu.arch.regs[VCPU_REGS_RBP];
 	save->rsi = svm->vcpu.arch.regs[VCPU_REGS_RSI];
 	save->rdi = svm->vcpu.arch.regs[VCPU_REGS_RDI];
+#ifdef X86_64
 	save->r8  = svm->vcpu.arch.regs[VCPU_REGS_R8];
 	save->r9  = svm->vcpu.arch.regs[VCPU_REGS_R9];
 	save->r10 = svm->vcpu.arch.regs[VCPU_REGS_R10];
@@ -537,6 +538,7 @@ static int sev_es_sync_vmsa(struct vcpu_svm *svm)
 	save->r13 = svm->vcpu.arch.regs[VCPU_REGS_R13];
 	save->r14 = svm->vcpu.arch.regs[VCPU_REGS_R14];
 	save->r15 = svm->vcpu.arch.regs[VCPU_REGS_R15];
+#endif
 	save->rip = svm->vcpu.arch.regs[VCPU_REGS_RIP];

 	/* Sync some non-GPR registers before encrypting */