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

[Michael Roth <michael.roth@xxxxxxx>]

From: Nikunj A Dadhania <nikunj@xxxxxxx>

KVM should use private memory for guests that have upm_mode flag set.

Add a kvm_x86_ops hook for determining UPM support that accounts for
this situation by only enabling UPM test mode in the case of non-SEV
guests.

Signed-off-by: Nikunj A Dadhania <nikunj@xxxxxxx>
[mdr: add x86 hook for determining restricted/private memory support]
Signed-off-by: Michael Roth <michael.roth@xxxxxxx>
---
 arch/x86/include/asm/kvm-x86-ops.h |  1 +
 arch/x86/include/asm/kvm_host.h    |  1 +
 arch/x86/kvm/svm/svm.c             | 10 ++++++++++
 arch/x86/kvm/x86.c                 |  8 ++++++++
 4 files changed, 20 insertions(+)

diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h
index abccd51dcfca..f530a550c092 100644
--- a/arch/x86/include/asm/kvm-x86-ops.h
+++ b/arch/x86/include/asm/kvm-x86-ops.h
@@ -131,6 +131,7 @@ 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 2b6244525107..9317abffbf68 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1635,6 +1635,7 @@ struct kvm_x86_ops {
 
 	void (*load_mmu_pgd)(struct kvm_vcpu *vcpu, hpa_t root_hpa,
 			     int root_level);
+	int (*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 91352d692845..7f3e4d91c0c6 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -4694,6 +4694,14 @@ static int svm_vm_init(struct kvm *kvm)
 	return 0;
 }
 
+static int svm_private_mem_enabled(struct kvm *kvm)
+{
+	if (sev_guest(kvm))
+		return kvm->arch.upm_mode ? 1 : 0;
+
+	return IS_ENABLED(CONFIG_HAVE_KVM_PRIVATE_MEM_TESTING) ? 1 : 0;
+}
+
 static struct kvm_x86_ops svm_x86_ops __initdata = {
 	.name = "kvm_amd",
 
@@ -4774,6 +4782,8 @@ 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 99ecf99bc4d2..bb6adb216054 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -12266,6 +12266,14 @@ 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)
+{
+	if (static_call(kvm_x86_private_mem_enabled)(kvm))
+		return true;
+
+	return false;
+}
+
 void kvm_arch_pre_destroy_vm(struct kvm *kvm)
 {
 	kvm_mmu_pre_destroy_vm(kvm);
-- 
2.25.1