linux-kernel - [PATCH v3 03/14] arm64: realm: Query IPA size from the RMM

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Date: Wed,  5 Jun 2024 10:29:55 +0100
From: Steven Price <steven.price@....com>
To: kvm@...r.kernel.org,
	kvmarm@...ts.linux.dev
Cc: Steven Price <steven.price@....com>,
	Catalin Marinas <catalin.marinas@....com>,
	Marc Zyngier <maz@...nel.org>,
	Will Deacon <will@...nel.org>,
	James Morse <james.morse@....com>,
	Oliver Upton <oliver.upton@...ux.dev>,
	Suzuki K Poulose <suzuki.poulose@....com>,
	Zenghui Yu <yuzenghui@...wei.com>,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	Joey Gouly <joey.gouly@....com>,
	Alexandru Elisei <alexandru.elisei@....com>,
	Christoffer Dall <christoffer.dall@....com>,
	Fuad Tabba <tabba@...gle.com>,
	linux-coco@...ts.linux.dev,
	Ganapatrao Kulkarni <gankulkarni@...amperecomputing.com>
Subject: [PATCH v3 03/14] 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.

Co-developed-by: Suzuki K Poulose <suzuki.poulose@....com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
Signed-off-by: Steven Price <steven.price@....com>
---
Changes since v2:
 * Drop unneeded extra brackets from PROT_NS_SHARED.
 * Drop the explicit alignment from 'config' as struct realm_config now
   specifies the alignment.
---
 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 b11cfb9fdd37..6c29f3b32eba 100644
--- a/arch/arm64/include/asm/pgtable-prot.h
+++ b/arch/arm64/include/asm/pgtable-prot.h
@@ -70,6 +70,9 @@
 #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 3a992bdfd6bb..d34e05b339ae 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 config;
+
+unsigned long prot_ns_shared;
+EXPORT_SYMBOL(prot_ns_shared);
+
 DEFINE_STATIC_KEY_FALSE_RO(rsi_present);
 EXPORT_SYMBOL(rsi_present);
 
@@ -63,6 +68,9 @@ 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