arm64: KVM: Support X-Gene guest VCPU on APM X-Gene host

This patch allows us to have X-Gene guest VCPU when using KVM arm64
on APM X-Gene host.

We add KVM_ARM_TARGET_XGENE_POTENZA for X-Gene Potenza compatible
guest VCPU and we return KVM_ARM_TARGET_XGENE_POTENZA in kvm_target_cpu()
when running on X-Gene host with Potenza core.

[maz: sanitized the commit log]

Signed-off-by: Anup Patel <anup.patel@linaro.org>
Signed-off-by: Pranavkumar Sawargaonkar <pranavkumar@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

3 files changed, 24 insertions, 14 deletions

diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
index 5031f4263937..d9f026bc1a27 100644
--- a/arch/arm64/include/uapi/asm/kvm.h
+++ b/arch/arm64/include/uapi/asm/kvm.h
@@ -55,8 +55,9 @@ struct kvm_regs {
 #define KVM_ARM_TARGET_AEM_V8           0
 #define KVM_ARM_TARGET_FOUNDATION_V8    1
 #define KVM_ARM_TARGET_CORTEX_A57       2
+#define KVM_ARM_TARGET_XGENE_POTENZA    3
 
-#define KVM_ARM_NUM_TARGETS             3
+#define KVM_ARM_NUM_TARGETS             4
 
 /* KVM_ARM_SET_DEVICE_ADDR ioctl id encoding */
 #define KVM_ARM_DEVICE_TYPE_SHIFT       0
diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
index 3f0731e53274..08745578d54d 100644
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c
@@ -207,20 +207,26 @@ int __attribute_const__ kvm_target_cpu(void)
         unsigned long implementor = read_cpuid_implementor();
         unsigned long part_number = read_cpuid_part_number();
 
-        if (implementor != ARM_CPU_IMP_ARM)
-                return -EINVAL;
+        switch (implementor) {
+        case ARM_CPU_IMP_ARM:
+                switch (part_number) {
+                case ARM_CPU_PART_AEM_V8:
+                        return KVM_ARM_TARGET_AEM_V8;
+                case ARM_CPU_PART_FOUNDATION:
+                        return KVM_ARM_TARGET_FOUNDATION_V8;
+                case ARM_CPU_PART_CORTEX_A57:
+                        return KVM_ARM_TARGET_CORTEX_A57;
+                };
+                break;
+        case ARM_CPU_IMP_APM:
+                switch (part_number) {
+                case APM_CPU_PART_POTENZA:
+                        return KVM_ARM_TARGET_XGENE_POTENZA;
+                };
+                break;
+        };
 
-        switch (part_number) {
-        case ARM_CPU_PART_AEM_V8:
-                return KVM_ARM_TARGET_AEM_V8;
-        case ARM_CPU_PART_FOUNDATION:
-                return KVM_ARM_TARGET_FOUNDATION_V8;
-        case ARM_CPU_PART_CORTEX_A57:
-                /* Currently handled by the generic backend */
-                return KVM_ARM_TARGET_CORTEX_A57;
-        default:
-                return -EINVAL;
-        }
+        return -EINVAL;
 }
 
 int kvm_vcpu_set_target(struct kvm_vcpu *vcpu,
diff --git a/arch/arm64/kvm/sys_regs_generic_v8.c b/arch/arm64/kvm/sys_regs_generic_v8.c
index 4268ab9356b1..8fe6f76b0edc 100644
--- a/arch/arm64/kvm/sys_regs_generic_v8.c
+++ b/arch/arm64/kvm/sys_regs_generic_v8.c
@@ -90,6 +90,9 @@ static int __init sys_reg_genericv8_init(void)
                                           &genericv8_target_table);
         kvm_register_target_sys_reg_table(KVM_ARM_TARGET_CORTEX_A57,
                                           &genericv8_target_table);
+        kvm_register_target_sys_reg_table(KVM_ARM_TARGET_XGENE_POTENZA,
+                                          &genericv8_target_table);
+
         return 0;
 }
 late_initcall(sys_reg_genericv8_init);