linux-kernel - Re: [PATCH] KVM: X86: Add missing KVM

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Message-ID: <749a21f9-ad88-af0e-bed7-b505ac57568d@redhat.com>
Date:   Fri, 5 Oct 2018 22:41:55 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     Radim Krčmář <rkrcmar@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org, kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Brijesh Singh <brijesh.singh@....com>,
        Borislav Petkov <bp@...e.de>
Subject: Re: [PATCH] KVM: X86: Add missing KVM_AMD dependency

On 05/10/2018 20:46, Guenter Roeck wrote:
> Analysis shows that commit 59414c9892208 ("KVM: SVM: Add support for
> KVM_SEV_LAUNCH_START command") added a dependency of KVM_AMD on
> CRYPTO_DEV_CCP_DD if CRYPTO_DEV_SP_PSP is enabled: If CRYPTO_DEV_CCP_DD
> is built as module, KVM_AMD must be built as module as well.
> 
> Fixes: 59414c9892208 ("KVM: SVM: Add support for KVM_SEV_LAUNCH_START command")
> Cc: Brijesh Singh <brijesh.singh@....com>
> Cc: Borislav Petkov <bp@...e.de>
> Signed-off-by: Guenter Roeck <linux@...ck-us.net>

This should be handled by

config KVM_AMD_SEV
        def_bool y
        bool "AMD Secure Encrypted Virtualization (SEV) support"
        depends on KVM_AMD && X86_64
        depends on CRYPTO_DEV_SP_PSP && !(KVM_AMD=y && CRYPTO_DEV_CCP_DD=m)
        ---help---
        Provides support for launching Encrypted VMs on AMD processors.

Maybe this works as well?  I haven't tested it yet:

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 89c4c5aa15f1..55f10b17d044 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -441,9 +441,13 @@ static inline bool svm_sev_enabled(void)

 static inline bool sev_guest(struct kvm *kvm)
 {
+#ifdef CONFIG_KVM_AMD_SEV
 	struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;

 	return sev->active;
+#else
+	return false;
+#endif
 }

 static inline int sev_get_asid(struct kvm *kvm)

Thanks,

Paolo