[PATCH v2 03/14] arm64: realm: Query IPA size from the RMM

Steven Price
2024-04-12T08:42:29Z

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.

Co-developed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Steven Price <steven.price@arm.com>
---
arch/arm64/include/asm/pgtable-prot.h | 3 +++
arch/arm64/kernel/rsi.c | 8 ++++++++
2 files changed, 11 insertions(+)

diff --git a/arch/arm64/include/asm/pgtable-prot.h b/arch/arm64/include/asm/pgtable-prot.h
index dd9ee67d1d87..15d8f0133af8 100644
--- a/arch/arm64/include/asm/pgtable-prot.h
+++ b/arch/arm64/include/asm/pgtable-prot.h
@@ -63,6 +63,9 @@
#include <asm/pgtable-types.h>

extern bool arm64_use_ng_mappings;
+extern unsigned long prot_ns_shared;
+
+#define PROT_NS_SHARED ((prot_ns_shared))

#define PTE_MAYBE_NG (arm64_use_ng_mappings ? PTE_NG : 0)
#define PMD_MAYBE_NG (arm64_use_ng_mappings ? PMD_SECT_NG : 0)
diff --git a/arch/arm64/kernel/rsi.c b/arch/arm64/kernel/rsi.c
index 1076649ac082..b93252ed6fc5 100644
--- a/arch/arm64/kernel/rsi.c
+++ b/arch/arm64/kernel/rsi.c
@@ -7,6 +7,11 @@
#include <linux/memblock.h>
#include <asm/rsi.h>

+struct realm_config __attribute((aligned(PAGE_SIZE))) config;
+
+unsigned long prot_ns_shared;
+EXPORT_SYMBOL(prot_ns_shared);
+
DEFINE_STATIC_KEY_FALSE_RO(rsi_present);
EXPORT_SYMBOL(rsi_present);

@@ -53,6 +58,9 @@ void __init arm64_rsi_init(void)
{
if (!rsi_version_matches())
return;
+ if (rsi_get_realm_config(&config))
+ return;
+ prot_ns_shared = BIT(config.ipa_bits - 1);

static_branch_enable(&rsi_present);
}
--
2.34.1