[RFC PATCH 04/28] arm64: RME: Check for RME support at KVM init

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Query the RMI version number and check if it is a compatible version. A
static key is also provided to signal that a supported RMM is available.

Functions are provided to query if a VM or VCPU is a realm (or rec)
which currently will always return false.

Signed-off-by: Steven Price <steven.price@xxxxxxx>
---
 arch/arm64/include/asm/kvm_emulate.h | 17 ++++++++++
 arch/arm64/include/asm/kvm_host.h    |  4 +++
 arch/arm64/include/asm/kvm_rme.h     | 22 +++++++++++++
 arch/arm64/include/asm/virt.h        |  1 +
 arch/arm64/kvm/Makefile              |  3 +-
 arch/arm64/kvm/arm.c                 |  8 +++++
 arch/arm64/kvm/rme.c                 | 49 ++++++++++++++++++++++++++++
 7 files changed, 103 insertions(+), 1 deletion(-)
 create mode 100644 arch/arm64/include/asm/kvm_rme.h
 create mode 100644 arch/arm64/kvm/rme.c

diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h
index 9bdba47f7e14..5a2b7229e83f 100644
--- a/arch/arm64/include/asm/kvm_emulate.h
+++ b/arch/arm64/include/asm/kvm_emulate.h
@@ -490,4 +490,21 @@ static inline bool vcpu_has_feature(struct kvm_vcpu *vcpu, int feature)
 	return test_bit(feature, vcpu->arch.features);
 }
 
+static inline bool kvm_is_realm(struct kvm *kvm)
+{
+	if (static_branch_unlikely(&kvm_rme_is_available))
+		return kvm->arch.is_realm;
+	return false;
+}
+
+static inline enum realm_state kvm_realm_state(struct kvm *kvm)
+{
+	return READ_ONCE(kvm->arch.realm.state);
+}
+
+static inline bool vcpu_is_rec(struct kvm_vcpu *vcpu)
+{
+	return false;
+}
+
 #endif /* __ARM64_KVM_EMULATE_H__ */
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 35a159d131b5..04347c3a8c6b 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -26,6 +26,7 @@
 #include <asm/fpsimd.h>
 #include <asm/kvm.h>
 #include <asm/kvm_asm.h>
+#include <asm/kvm_rme.h>
 
 #define __KVM_HAVE_ARCH_INTC_INITIALIZED
 
@@ -240,6 +241,9 @@ struct kvm_arch {
 	 * the associated pKVM instance in the hypervisor.
 	 */
 	struct kvm_protected_vm pkvm;
+
+	bool is_realm;
+	struct realm realm;
 };
 
 struct kvm_vcpu_fault_info {
diff --git a/arch/arm64/include/asm/kvm_rme.h b/arch/arm64/include/asm/kvm_rme.h
new file mode 100644
index 000000000000..c26bc2c6770d
--- /dev/null
+++ b/arch/arm64/include/asm/kvm_rme.h
@@ -0,0 +1,22 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2023 ARM Ltd.
+ */
+
+#ifndef __ASM_KVM_RME_H
+#define __ASM_KVM_RME_H
+
+enum realm_state {
+	REALM_STATE_NONE,
+	REALM_STATE_NEW,
+	REALM_STATE_ACTIVE,
+	REALM_STATE_DYING
+};
+
+struct realm {
+	enum realm_state state;
+};
+
+int kvm_init_rme(void);
+
+#endif
diff --git a/arch/arm64/include/asm/virt.h b/arch/arm64/include/asm/virt.h
index 4eb601e7de50..be1383e26626 100644
--- a/arch/arm64/include/asm/virt.h
+++ b/arch/arm64/include/asm/virt.h
@@ -80,6 +80,7 @@ void __hyp_set_vectors(phys_addr_t phys_vector_base);
 void __hyp_reset_vectors(void);
 
 DECLARE_STATIC_KEY_FALSE(kvm_protected_mode_initialized);
+DECLARE_STATIC_KEY_FALSE(kvm_rme_is_available);
 
 /* Reports the availability of HYP mode */
 static inline bool is_hyp_mode_available(void)
diff --git a/arch/arm64/kvm/Makefile b/arch/arm64/kvm/Makefile
index 5e33c2d4645a..d2f0400c50da 100644
--- a/arch/arm64/kvm/Makefile
+++ b/arch/arm64/kvm/Makefile
@@ -20,7 +20,8 @@ kvm-y += arm.o mmu.o mmio.o psci.o hypercalls.o pvtime.o \
 	 vgic/vgic-v3.o vgic/vgic-v4.o \
 	 vgic/vgic-mmio.o vgic/vgic-mmio-v2.o \
 	 vgic/vgic-mmio-v3.o vgic/vgic-kvm-device.o \
-	 vgic/vgic-its.o vgic/vgic-debug.o
+	 vgic/vgic-its.o vgic/vgic-debug.o \
+	 rme.o
 
 kvm-$(CONFIG_HW_PERF_EVENTS)  += pmu-emul.o pmu.o
 
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 9c5573bc4614..d97b39d042ab 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -38,6 +38,7 @@
 #include <asm/kvm_asm.h>
 #include <asm/kvm_mmu.h>
 #include <asm/kvm_pkvm.h>
+#include <asm/kvm_rme.h>
 #include <asm/kvm_emulate.h>
 #include <asm/sections.h>
 
@@ -47,6 +48,7 @@
 
 static enum kvm_mode kvm_mode = KVM_MODE_DEFAULT;
 DEFINE_STATIC_KEY_FALSE(kvm_protected_mode_initialized);
+DEFINE_STATIC_KEY_FALSE(kvm_rme_is_available);
 
 DECLARE_KVM_HYP_PER_CPU(unsigned long, kvm_hyp_vector);
 
@@ -2213,6 +2215,12 @@ int kvm_arch_init(void *opaque)
 
 	in_hyp_mode = is_kernel_in_hyp_mode();
 
+	if (in_hyp_mode) {
+		err = kvm_init_rme();
+		if (err)
+			return err;
+	}
+
 	if (cpus_have_final_cap(ARM64_WORKAROUND_DEVICE_LOAD_ACQUIRE) ||
 	    cpus_have_final_cap(ARM64_WORKAROUND_1508412))
 		kvm_info("Guests without required CPU erratum workarounds can deadlock system!\n" \
diff --git a/arch/arm64/kvm/rme.c b/arch/arm64/kvm/rme.c
new file mode 100644
index 000000000000..f6b587bc116e
--- /dev/null
+++ b/arch/arm64/kvm/rme.c
@@ -0,0 +1,49 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2023 ARM Ltd.
+ */
+
+#include <linux/kvm_host.h>
+
+#include <asm/rmi_cmds.h>
+#include <asm/virt.h>
+
+static int rmi_check_version(void)
+{
+	struct arm_smccc_res res;
+	int version_major, version_minor;
+
+	arm_smccc_1_1_invoke(SMC_RMI_VERSION, &res);
+
+	if (res.a0 == SMCCC_RET_NOT_SUPPORTED)
+		return -ENXIO;
+
+	version_major = RMI_ABI_VERSION_GET_MAJOR(res.a0);
+	version_minor = RMI_ABI_VERSION_GET_MINOR(res.a0);
+
+	if (version_major != RMI_ABI_MAJOR_VERSION) {
+		kvm_err("Unsupported RMI ABI (version %d.%d) we support %d\n",
+			version_major, version_minor,
+			RMI_ABI_MAJOR_VERSION);
+		return -ENXIO;
+	}
+
+	kvm_info("RMI ABI version %d.%d\n", version_major, version_minor);
+
+	return 0;
+}
+
+int kvm_init_rme(void)
+{
+	if (PAGE_SIZE != SZ_4K)
+		/* Only 4k page size on the host is supported */
+		return 0;
+
+	if (rmi_check_version())
+		/* Continue without realm support */
+		return 0;
+
+	/* Future patch will enable static branch kvm_rme_is_available */
+
+	return 0;
+}
-- 
2.34.1




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