linux-kernel - Re: [PATCH RFC v7 03/64] KVM: SVM: Advertise private memory support to KVM

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Date:   Fri, 23 Dec 2022 17:56:50 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Michael Roth <michael.roth@....com>
Cc:     kvm@...r.kernel.org, linux-coco@...ts.linux.dev,
        linux-mm@...ck.org, linux-crypto@...r.kernel.org, x86@...nel.org,
        linux-kernel@...r.kernel.org, tglx@...utronix.de, mingo@...hat.com,
        jroedel@...e.de, thomas.lendacky@....com, hpa@...or.com,
        ardb@...nel.org, pbonzini@...hat.com, seanjc@...gle.com,
        vkuznets@...hat.com, wanpengli@...cent.com, jmattson@...gle.com,
        luto@...nel.org, dave.hansen@...ux.intel.com, slp@...hat.com,
        pgonda@...gle.com, peterz@...radead.org,
        srinivas.pandruvada@...ux.intel.com, rientjes@...gle.com,
        dovmurik@...ux.ibm.com, tobin@....com, vbabka@...e.cz,
        kirill@...temov.name, ak@...ux.intel.com, tony.luck@...el.com,
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        alpergun@...gle.com, dgilbert@...hat.com, jarkko@...nel.org,
        ashish.kalra@....com, harald@...fian.com,
        Nikunj A Dadhania <nikunj@....com>
Subject: Re: [PATCH RFC v7 03/64] KVM: SVM: Advertise private memory support
 to KVM

On Wed, Dec 14, 2022 at 01:39:55PM -0600, Michael Roth wrote:
> +       bool (*private_mem_enabled)(struct kvm *kvm);

This looks like a function returning boolean to me. IOW, you can
simplify this to:

diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h
index 82ba4a564e58..4449aeff0dff 100644
--- a/arch/x86/include/asm/kvm-x86-ops.h
+++ b/arch/x86/include/asm/kvm-x86-ops.h
@@ -129,6 +129,7 @@ KVM_X86_OP(msr_filter_changed)
 KVM_X86_OP(complete_emulated_msr)
 KVM_X86_OP(vcpu_deliver_sipi_vector)
 KVM_X86_OP_OPTIONAL_RET0(vcpu_get_apicv_inhibit_reasons);
+KVM_X86_OP_OPTIONAL_RET0(private_mem_enabled);
 
 #undef KVM_X86_OP
 #undef KVM_X86_OP_OPTIONAL
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 1da0474edb2d..1b4b89ddeb55 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1574,6 +1574,7 @@ struct kvm_x86_ops {
 
 	void (*load_mmu_pgd)(struct kvm_vcpu *vcpu, hpa_t root_hpa,
 			     int root_level);
+	bool (*private_mem_enabled)(struct kvm *kvm);
 
 	bool (*has_wbinvd_exit)(void);
 
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index ce362e88a567..73b780fa4653 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -4680,6 +4680,14 @@ static int svm_vm_init(struct kvm *kvm)
 	return 0;
 }
 
+static bool svm_private_mem_enabled(struct kvm *kvm)
+{
+	if (sev_guest(kvm))
+		return kvm->arch.upm_mode;
+
+	return IS_ENABLED(CONFIG_HAVE_KVM_PRIVATE_MEM_TESTING);
+}
+
 static struct kvm_x86_ops svm_x86_ops __initdata = {
 	.name = "kvm_amd",
 
@@ -4760,6 +4768,8 @@ static struct kvm_x86_ops svm_x86_ops __initdata = {
 
 	.vcpu_after_set_cpuid = svm_vcpu_after_set_cpuid,
 
+	.private_mem_enabled = svm_private_mem_enabled,
+
 	.has_wbinvd_exit = svm_has_wbinvd_exit,
 
 	.get_l2_tsc_offset = svm_get_l2_tsc_offset,
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 823646d601db..9a1ca59d36a4 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -12556,6 +12556,11 @@ void __user * __x86_set_memory_region(struct kvm *kvm, int id, gpa_t gpa,
 }
 EXPORT_SYMBOL_GPL(__x86_set_memory_region);
 
+bool kvm_arch_has_private_mem(struct kvm *kvm)
+{
+	return static_call(kvm_x86_private_mem_enabled)(kvm);
+}
+
 void kvm_arch_pre_destroy_vm(struct kvm *kvm)
 {
 	kvm_mmu_pre_destroy_vm(kvm);

-- 
Regards/Gruss,
    Boris.

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