1 files changed, 142 insertions, 0 deletions
diff --git a/arch/arm64/kernel/rsi.c b/arch/arm64/kernel/rsi.c
new file mode 100644
index 000000000000..3031f25c32ef
--- /dev/null
+++ b/arch/arm64/kernel/rsi.c
@@ -0,0 +1,142 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2023 ARM Ltd.
+ */
+
+#include <linux/jump_label.h>
+#include <linux/memblock.h>
+#include <linux/psci.h>
+#include <linux/swiotlb.h>
+#include <linux/cc_platform.h>
+
+#include <asm/io.h>
+#include <asm/mem_encrypt.h>
+#include <asm/rsi.h>
+
+static struct realm_config config;
+
+unsigned long prot_ns_shared;
+EXPORT_SYMBOL(prot_ns_shared);
+
+DEFINE_STATIC_KEY_FALSE_RO(rsi_present);
+EXPORT_SYMBOL(rsi_present);
+
+bool cc_platform_has(enum cc_attr attr)
+{
+	switch (attr) {
+	case CC_ATTR_MEM_ENCRYPT:
+		return is_realm_world();
+	default:
+		return false;
+	}
+}
+EXPORT_SYMBOL_GPL(cc_platform_has);
+
+static bool rsi_version_matches(void)
+{
+	unsigned long ver_lower, ver_higher;
+	unsigned long ret = rsi_request_version(RSI_ABI_VERSION,
+						&ver_lower,
+						&ver_higher);
+
+	if (ret == SMCCC_RET_NOT_SUPPORTED)
+		return false;
+
+	if (ret != RSI_SUCCESS) {
+		pr_err("RME: RMM doesn't support RSI version %lu.%lu. Supported range: %lu.%lu-%lu.%lu\n",
+		       RSI_ABI_VERSION_MAJOR, RSI_ABI_VERSION_MINOR,
+		       RSI_ABI_VERSION_GET_MAJOR(ver_lower),
+		       RSI_ABI_VERSION_GET_MINOR(ver_lower),
+		       RSI_ABI_VERSION_GET_MAJOR(ver_higher),
+		       RSI_ABI_VERSION_GET_MINOR(ver_higher));
+		return false;
+	}
+
+	pr_info("RME: Using RSI version %lu.%lu\n",
+		RSI_ABI_VERSION_GET_MAJOR(ver_lower),
+		RSI_ABI_VERSION_GET_MINOR(ver_lower));
+
+	return true;
+}
+
+static void __init arm64_rsi_setup_memory(void)
+{
+	u64 i;
+	phys_addr_t start, end;
+
+	/*
+	 * Iterate over the available memory ranges and convert the state to
+	 * protected memory. We should take extra care to ensure that we DO NOT
+	 * permit any "DESTROYED" pages to be converted to "RAM".
+	 *
+	 * panic() is used because if the attempt to switch the memory to
+	 * protected has failed here, then future accesses to the memory are
+	 * simply going to be reflected as a SEA (Synchronous External Abort)
+	 * which we can't handle.  Bailing out early prevents the guest limping
+	 * on and dying later.
+	 */
+	for_each_mem_range(i, &start, &end) {
+		if (rsi_set_memory_range_protected_safe(start, end)) {
+			panic("Failed to set memory range to protected: %pa-%pa",
+			      &start, &end);
+		}
+	}
+}
+
+bool __arm64_is_protected_mmio(phys_addr_t base, size_t size)
+{
+	enum ripas ripas;
+	phys_addr_t end, top;
+
+	/* Overflow ? */
+	if (WARN_ON(base + size <= base))
+		return false;
+
+	end = ALIGN(base + size, RSI_GRANULE_SIZE);
+	base = ALIGN_DOWN(base, RSI_GRANULE_SIZE);
+
+	while (base < end) {
+		if (WARN_ON(rsi_ipa_state_get(base, end, &ripas, &top)))
+			break;
+		if (WARN_ON(top <= base))
+			break;
+		if (ripas != RSI_RIPAS_DEV)
+			break;
+		base = top;
+	}
+
+	return base >= end;
+}
+EXPORT_SYMBOL(__arm64_is_protected_mmio);
+
+static int realm_ioremap_hook(phys_addr_t phys, size_t size, pgprot_t *prot)
+{
+	if (__arm64_is_protected_mmio(phys, size))
+		*prot = pgprot_encrypted(*prot);
+	else
+		*prot = pgprot_decrypted(*prot);
+
+	return 0;
+}
+
+void __init arm64_rsi_init(void)
+{
+	if (arm_smccc_1_1_get_conduit() != SMCCC_CONDUIT_SMC)
+		return;
+	if (!rsi_version_matches())
+		return;
+	if (WARN_ON(rsi_get_realm_config(&config)))
+		return;
+	prot_ns_shared = BIT(config.ipa_bits - 1);
+
+	if (arm64_ioremap_prot_hook_register(realm_ioremap_hook))
+		return;
+
+	if (realm_register_memory_enc_ops())
+		return;
+
+	arm64_rsi_setup_memory();
+
+	static_branch_enable(&rsi_present);
+}
+