arm/arm64: KVM: Advertise SMCCC v1.1

The new SMC Calling Convention (v1.1) allows for a reduced overhead
when calling into the firmware, and provides a new feature discovery
mechanism.

Make it visible to KVM guests.

Tested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

5 files changed, 39 insertions, 4 deletions

diff --git a/arch/arm/kvm/handle_exit.c b/arch/arm/kvm/handle_exit.c
index 230ae4079108..910bd8dabb3c 100644
--- a/arch/arm/kvm/handle_exit.c
+++ b/arch/arm/kvm/handle_exit.c
@@ -36,7 +36,7 @@ static int handle_hvc(struct kvm_vcpu *vcpu, struct kvm_run *run)
                       kvm_vcpu_hvc_get_imm(vcpu));
         vcpu->stat.hvc_exit_stat++;
 
-        ret = kvm_psci_call(vcpu);
+        ret = kvm_hvc_call_handler(vcpu);
         if (ret < 0) {
                 vcpu_set_reg(vcpu, 0, ~0UL);
                 return 1;
diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c
index 588f910632a7..e5e741bfffe1 100644
--- a/arch/arm64/kvm/handle_exit.c
+++ b/arch/arm64/kvm/handle_exit.c
@@ -52,7 +52,7 @@ static int handle_hvc(struct kvm_vcpu *vcpu, struct kvm_run *run)
                             kvm_vcpu_hvc_get_imm(vcpu));
         vcpu->stat.hvc_exit_stat++;
 
-        ret = kvm_psci_call(vcpu);
+        ret = kvm_hvc_call_handler(vcpu);
         if (ret < 0) {
                 vcpu_set_reg(vcpu, 0, ~0UL);
                 return 1;
diff --git a/include/kvm/arm_psci.h b/include/kvm/arm_psci.h
index 32360432cff5..ed1dd8088f1c 100644
--- a/include/kvm/arm_psci.h
+++ b/include/kvm/arm_psci.h
@@ -27,6 +27,6 @@
 #define KVM_ARM_PSCI_LATEST     KVM_ARM_PSCI_1_0
 
 int kvm_psci_version(struct kvm_vcpu *vcpu);
-int kvm_psci_call(struct kvm_vcpu *vcpu);
+int kvm_hvc_call_handler(struct kvm_vcpu *vcpu);
 
 #endif /* __KVM_ARM_PSCI_H__ */
diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h
index 4c5bca38c653..dc68aa5a7261 100644
--- a/include/linux/arm-smccc.h
+++ b/include/linux/arm-smccc.h
@@ -60,6 +60,19 @@
 #define ARM_SMCCC_QUIRK_NONE            0
 #define ARM_SMCCC_QUIRK_QCOM_A6         1 /* Save/restore register a6 */
 
+#define ARM_SMCCC_VERSION_1_0           0x10000
+#define ARM_SMCCC_VERSION_1_1           0x10001
+
+#define ARM_SMCCC_VERSION_FUNC_ID                                       \
+        ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,                         \
+                           ARM_SMCCC_SMC_32,                            \
+                           0, 0)
+
+#define ARM_SMCCC_ARCH_FEATURES_FUNC_ID                                 \
+        ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,                         \
+                           ARM_SMCCC_SMC_32,                            \
+                           0, 1)
+
 #ifndef __ASSEMBLY__
 
 #include <linux/linkage.h>
diff --git a/virt/kvm/arm/psci.c b/virt/kvm/arm/psci.c
index 3e7c63e15f04..46a98fee3ef5 100644
--- a/virt/kvm/arm/psci.c
+++ b/virt/kvm/arm/psci.c
@@ -15,6 +15,7 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <linux/arm-smccc.h>
 #include <linux/preempt.h>
 #include <linux/kvm_host.h>
 #include <linux/wait.h>
@@ -339,6 +340,7 @@ static int kvm_psci_1_0_call(struct kvm_vcpu *vcpu)
                 case PSCI_0_2_FN_SYSTEM_OFF:
                 case PSCI_0_2_FN_SYSTEM_RESET:
                 case PSCI_1_0_FN_PSCI_FEATURES:
+                case ARM_SMCCC_VERSION_FUNC_ID:
                         val = 0;
                         break;
                 default:
@@ -393,7 +395,7 @@ static int kvm_psci_0_1_call(struct kvm_vcpu *vcpu)
  * Errors:
  * -EINVAL: Unrecognized PSCI function
  */
-int kvm_psci_call(struct kvm_vcpu *vcpu)
+static int kvm_psci_call(struct kvm_vcpu *vcpu)
 {
         switch (kvm_psci_version(vcpu)) {
         case KVM_ARM_PSCI_1_0:
@@ -406,3 +408,23 @@ int kvm_psci_call(struct kvm_vcpu *vcpu)
                 return -EINVAL;
         };
 }
+
+int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
+{
+        u32 func_id = smccc_get_function(vcpu);
+        u32 val = PSCI_RET_NOT_SUPPORTED;
+
+        switch (func_id) {
+        case ARM_SMCCC_VERSION_FUNC_ID:
+                val = ARM_SMCCC_VERSION_1_1;
+                break;
+        case ARM_SMCCC_ARCH_FEATURES_FUNC_ID:
+                /* Nothing supported yet */
+                break;
+        default:
+                return kvm_psci_call(vcpu);
+        }
+
+        smccc_set_retval(vcpu, val, 0, 0, 0);
+        return 1;
+}