1 files changed, 304 insertions, 0 deletions
diff --git a/arch/arm64/kvm/hyp/nvhe/psci-relay.c b/arch/arm64/kvm/hyp/nvhe/psci-relay.c
new file mode 100644
index 000000000..08508783e
--- /dev/null
+++ b/arch/arm64/kvm/hyp/nvhe/psci-relay.c
@@ -0,0 +1,304 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2020 - Google LLC
+ * Author: David Brazdil <dbrazdil@google.com>
+ */
+
+#include <asm/kvm_asm.h>
+#include <asm/kvm_hyp.h>
+#include <asm/kvm_mmu.h>
+#include <linux/arm-smccc.h>
+#include <linux/kvm_host.h>
+#include <uapi/linux/psci.h>
+
+#include <nvhe/memory.h>
+#include <nvhe/trap_handler.h>
+
+void kvm_hyp_cpu_entry(unsigned long r0);
+void kvm_hyp_cpu_resume(unsigned long r0);
+
+void __noreturn __host_enter(struct kvm_cpu_context *host_ctxt);
+
+/* Config options set by the host. */
+struct kvm_host_psci_config __ro_after_init kvm_host_psci_config;
+
+#define INVALID_CPU_ID	UINT_MAX
+
+struct psci_boot_args {
+	atomic_t lock;
+	unsigned long pc;
+	unsigned long r0;
+};
+
+#define PSCI_BOOT_ARGS_UNLOCKED		0
+#define PSCI_BOOT_ARGS_LOCKED		1
+
+#define PSCI_BOOT_ARGS_INIT					\
+	((struct psci_boot_args){				\
+		.lock = ATOMIC_INIT(PSCI_BOOT_ARGS_UNLOCKED),	\
+	})
+
+static DEFINE_PER_CPU(struct psci_boot_args, cpu_on_args) = PSCI_BOOT_ARGS_INIT;
+static DEFINE_PER_CPU(struct psci_boot_args, suspend_args) = PSCI_BOOT_ARGS_INIT;
+
+#define	is_psci_0_1(what, func_id)					\
+	(kvm_host_psci_config.psci_0_1_ ## what ## _implemented &&	\
+	 (func_id) == kvm_host_psci_config.function_ids_0_1.what)
+
+static bool is_psci_0_1_call(u64 func_id)
+{
+	return (is_psci_0_1(cpu_suspend, func_id) ||
+		is_psci_0_1(cpu_on, func_id) ||
+		is_psci_0_1(cpu_off, func_id) ||
+		is_psci_0_1(migrate, func_id));
+}
+
+static bool is_psci_0_2_call(u64 func_id)
+{
+	/* SMCCC reserves IDs 0x00-1F with the given 32/64-bit base for PSCI. */
+	return (PSCI_0_2_FN(0) <= func_id && func_id <= PSCI_0_2_FN(31)) ||
+	       (PSCI_0_2_FN64(0) <= func_id && func_id <= PSCI_0_2_FN64(31));
+}
+
+static unsigned long psci_call(unsigned long fn, unsigned long arg0,
+			       unsigned long arg1, unsigned long arg2)
+{
+	struct arm_smccc_res res;
+
+	arm_smccc_1_1_smc(fn, arg0, arg1, arg2, &res);
+	return res.a0;
+}
+
+static unsigned long psci_forward(struct kvm_cpu_context *host_ctxt)
+{
+	return psci_call(cpu_reg(host_ctxt, 0), cpu_reg(host_ctxt, 1),
+			 cpu_reg(host_ctxt, 2), cpu_reg(host_ctxt, 3));
+}
+
+static unsigned int find_cpu_id(u64 mpidr)
+{
+	unsigned int i;
+
+	/* Reject invalid MPIDRs */
+	if (mpidr & ~MPIDR_HWID_BITMASK)
+		return INVALID_CPU_ID;
+
+	for (i = 0; i < NR_CPUS; i++) {
+		if (cpu_logical_map(i) == mpidr)
+			return i;
+	}
+
+	return INVALID_CPU_ID;
+}
+
+static __always_inline bool try_acquire_boot_args(struct psci_boot_args *args)
+{
+	return atomic_cmpxchg_acquire(&args->lock,
+				      PSCI_BOOT_ARGS_UNLOCKED,
+				      PSCI_BOOT_ARGS_LOCKED) ==
+		PSCI_BOOT_ARGS_UNLOCKED;
+}
+
+static __always_inline void release_boot_args(struct psci_boot_args *args)
+{
+	atomic_set_release(&args->lock, PSCI_BOOT_ARGS_UNLOCKED);
+}
+
+static int psci_cpu_on(u64 func_id, struct kvm_cpu_context *host_ctxt)
+{
+	DECLARE_REG(u64, mpidr, host_ctxt, 1);
+	DECLARE_REG(unsigned long, pc, host_ctxt, 2);
+	DECLARE_REG(unsigned long, r0, host_ctxt, 3);
+
+	unsigned int cpu_id;
+	struct psci_boot_args *boot_args;
+	struct kvm_nvhe_init_params *init_params;
+	int ret;
+
+	/*
+	 * Find the logical CPU ID for the given MPIDR. The search set is
+	 * the set of CPUs that were online at the point of KVM initialization.
+	 * Booting other CPUs is rejected because their cpufeatures were not
+	 * checked against the finalized capabilities. This could be relaxed
+	 * by doing the feature checks in hyp.
+	 */
+	cpu_id = find_cpu_id(mpidr);
+	if (cpu_id == INVALID_CPU_ID)
+		return PSCI_RET_INVALID_PARAMS;
+
+	boot_args = per_cpu_ptr(&cpu_on_args, cpu_id);
+	init_params = per_cpu_ptr(&kvm_init_params, cpu_id);
+
+	/* Check if the target CPU is already being booted. */
+	if (!try_acquire_boot_args(boot_args))
+		return PSCI_RET_ALREADY_ON;
+
+	boot_args->pc = pc;
+	boot_args->r0 = r0;
+	wmb();
+
+	ret = psci_call(func_id, mpidr,
+			__hyp_pa(&kvm_hyp_cpu_entry),
+			__hyp_pa(init_params));
+
+	/* If successful, the lock will be released by the target CPU. */
+	if (ret != PSCI_RET_SUCCESS)
+		release_boot_args(boot_args);
+
+	return ret;
+}
+
+static int psci_cpu_suspend(u64 func_id, struct kvm_cpu_context *host_ctxt)
+{
+	DECLARE_REG(u64, power_state, host_ctxt, 1);
+	DECLARE_REG(unsigned long, pc, host_ctxt, 2);
+	DECLARE_REG(unsigned long, r0, host_ctxt, 3);
+
+	struct psci_boot_args *boot_args;
+	struct kvm_nvhe_init_params *init_params;
+
+	boot_args = this_cpu_ptr(&suspend_args);
+	init_params = this_cpu_ptr(&kvm_init_params);
+
+	/*
+	 * No need to acquire a lock before writing to boot_args because a core
+	 * can only suspend itself. Racy CPU_ON calls use a separate struct.
+	 */
+	boot_args->pc = pc;
+	boot_args->r0 = r0;
+
+	/*
+	 * Will either return if shallow sleep state, or wake up into the entry
+	 * point if it is a deep sleep state.
+	 */
+	return psci_call(func_id, power_state,
+			 __hyp_pa(&kvm_hyp_cpu_resume),
+			 __hyp_pa(init_params));
+}
+
+static int psci_system_suspend(u64 func_id, struct kvm_cpu_context *host_ctxt)
+{
+	DECLARE_REG(unsigned long, pc, host_ctxt, 1);
+	DECLARE_REG(unsigned long, r0, host_ctxt, 2);
+
+	struct psci_boot_args *boot_args;
+	struct kvm_nvhe_init_params *init_params;
+
+	boot_args = this_cpu_ptr(&suspend_args);
+	init_params = this_cpu_ptr(&kvm_init_params);
+
+	/*
+	 * No need to acquire a lock before writing to boot_args because a core
+	 * can only suspend itself. Racy CPU_ON calls use a separate struct.
+	 */
+	boot_args->pc = pc;
+	boot_args->r0 = r0;
+
+	/* Will only return on error. */
+	return psci_call(func_id,
+			 __hyp_pa(&kvm_hyp_cpu_resume),
+			 __hyp_pa(init_params), 0);
+}
+
+asmlinkage void __noreturn kvm_host_psci_cpu_entry(bool is_cpu_on)
+{
+	struct psci_boot_args *boot_args;
+	struct kvm_cpu_context *host_ctxt;
+
+	host_ctxt = &this_cpu_ptr(&kvm_host_data)->host_ctxt;
+
+	if (is_cpu_on)
+		boot_args = this_cpu_ptr(&cpu_on_args);
+	else
+		boot_args = this_cpu_ptr(&suspend_args);
+
+	cpu_reg(host_ctxt, 0) = boot_args->r0;
+	write_sysreg_el2(boot_args->pc, SYS_ELR);
+
+	if (is_cpu_on)
+		release_boot_args(boot_args);
+
+	__host_enter(host_ctxt);
+}
+
+static unsigned long psci_0_1_handler(u64 func_id, struct kvm_cpu_context *host_ctxt)
+{
+	if (is_psci_0_1(cpu_off, func_id) || is_psci_0_1(migrate, func_id))
+		return psci_forward(host_ctxt);
+	if (is_psci_0_1(cpu_on, func_id))
+		return psci_cpu_on(func_id, host_ctxt);
+	if (is_psci_0_1(cpu_suspend, func_id))
+		return psci_cpu_suspend(func_id, host_ctxt);
+
+	return PSCI_RET_NOT_SUPPORTED;
+}
+
+static unsigned long psci_0_2_handler(u64 func_id, struct kvm_cpu_context *host_ctxt)
+{
+	switch (func_id) {
+	case PSCI_0_2_FN_PSCI_VERSION:
+	case PSCI_0_2_FN_CPU_OFF:
+	case PSCI_0_2_FN64_AFFINITY_INFO:
+	case PSCI_0_2_FN64_MIGRATE:
+	case PSCI_0_2_FN_MIGRATE_INFO_TYPE:
+	case PSCI_0_2_FN64_MIGRATE_INFO_UP_CPU:
+		return psci_forward(host_ctxt);
+	/*
+	 * SYSTEM_OFF/RESET should not return according to the spec.
+	 * Allow it so as to stay robust to broken firmware.
+	 */
+	case PSCI_0_2_FN_SYSTEM_OFF:
+	case PSCI_0_2_FN_SYSTEM_RESET:
+		return psci_forward(host_ctxt);
+	case PSCI_0_2_FN64_CPU_SUSPEND:
+		return psci_cpu_suspend(func_id, host_ctxt);
+	case PSCI_0_2_FN64_CPU_ON:
+		return psci_cpu_on(func_id, host_ctxt);
+	default:
+		return PSCI_RET_NOT_SUPPORTED;
+	}
+}
+
+static unsigned long psci_1_0_handler(u64 func_id, struct kvm_cpu_context *host_ctxt)
+{
+	switch (func_id) {
+	case PSCI_1_0_FN_PSCI_FEATURES:
+	case PSCI_1_0_FN_SET_SUSPEND_MODE:
+	case PSCI_1_1_FN64_SYSTEM_RESET2:
+		return psci_forward(host_ctxt);
+	case PSCI_1_0_FN64_SYSTEM_SUSPEND:
+		return psci_system_suspend(func_id, host_ctxt);
+	default:
+		return psci_0_2_handler(func_id, host_ctxt);
+	}
+}
+
+bool kvm_host_psci_handler(struct kvm_cpu_context *host_ctxt)
+{
+	DECLARE_REG(u64, func_id, host_ctxt, 0);
+	unsigned long ret;
+
+	switch (kvm_host_psci_config.version) {
+	case PSCI_VERSION(0, 1):
+		if (!is_psci_0_1_call(func_id))
+			return false;
+		ret = psci_0_1_handler(func_id, host_ctxt);
+		break;
+	case PSCI_VERSION(0, 2):
+		if (!is_psci_0_2_call(func_id))
+			return false;
+		ret = psci_0_2_handler(func_id, host_ctxt);
+		break;
+	default:
+		if (!is_psci_0_2_call(func_id))
+			return false;
+		ret = psci_1_0_handler(func_id, host_ctxt);
+		break;
+	}
+
+	cpu_reg(host_ctxt, 0) = ret;
+	cpu_reg(host_ctxt, 1) = 0;
+	cpu_reg(host_ctxt, 2) = 0;
+	cpu_reg(host_ctxt, 3) = 0;
+	return true;
+}