arm64: realm: Query IPA size from the RMM

The top bit of the configured IPA size is used as an attribute to
control whether the address is protected or shared. Query the
configuration from the RMM to assertain which bit this is.

Reviewed-by: Catalin Marinas <[email protected]>
Reviewed-by: Gavin Shan <[email protected]>
Co-developed-by: Suzuki K Poulose <[email protected]>
Signed-off-by: Suzuki K Poulose <[email protected]>
Signed-off-by: Steven Price <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Catalin Marinas <[email protected]>

Author: Steven Price

arch/arm64/include/asm/pgtable-prot.h

@@ -68,8 +68,12 @@
 
 #include <asm/cpufeature.h>
 #include <asm/pgtable-types.h>
+#include <asm/rsi.h>
 
 extern bool arm64_use_ng_mappings;
+extern unsigned long prot_ns_shared;
+
+#define PROT_NS_SHARED		(is_realm_world() ? prot_ns_shared : 0)
 
 #define PTE_MAYBE_NG		(arm64_use_ng_mappings ? PTE_NG : 0)
 #define PMD_MAYBE_NG		(arm64_use_ng_mappings ? PMD_SECT_NG : 0)

arch/arm64/kernel/rsi.c

@@ -8,6 +8,11 @@
 #include <linux/psci.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);
 
@@ -68,6 +73,9 @@ void __init arm64_rsi_init(void)
 		return;
 	if (!rsi_version_matches())
 		return;
+	if (WARN_ON(rsi_get_realm_config(&config)))
+		return;
+	prot_ns_shared = BIT(config.ipa_bits - 1);
 
 	arm64_rsi_setup_memory();