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

Steven Price
2023-01-27T11:31:59Z

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@arm.com>
---
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