linux-kernel - [PATCH v7 05/11] arm64: rsi: Map unprotected MMIO as decrypted

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Message-Id: <20241017131434.40935-6-steven.price@arm.com>
Date: Thu, 17 Oct 2024 14:14:28 +0100
From: Steven Price <steven.price@....com>
To: kvm@...r.kernel.org,
	kvmarm@...ts.linux.dev
Cc: Suzuki K Poulose <suzuki.poulose@....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>,
	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>,
	Gavin Shan <gshan@...hat.com>,
	Shanker Donthineni <sdonthineni@...dia.com>,
	Alper Gun <alpergun@...gle.com>,
	"Aneesh Kumar K . V" <aneesh.kumar@...nel.org>,
	Steven Price <steven.price@....com>
Subject: [PATCH v7 05/11] arm64: rsi: Map unprotected MMIO as decrypted

From: Suzuki K Poulose <suzuki.poulose@....com>

Instead of marking every MMIO as shared, check if the given region is
"Protected" and apply the permissions accordingly.

Reviewed-by: Gavin Shan <gshan@...hat.com>
Reviewed-by: Catalin Marinas <catalin.marinas@....com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
Signed-off-by: Steven Price <steven.price@....com>
---
New patch for v5
---
 arch/arm64/kernel/rsi.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/arch/arm64/kernel/rsi.c b/arch/arm64/kernel/rsi.c
index 7e7934c4fca0..3e0c83e2296f 100644
--- a/arch/arm64/kernel/rsi.c
+++ b/arch/arm64/kernel/rsi.c
@@ -6,6 +6,8 @@
 #include <linux/jump_label.h>
 #include <linux/memblock.h>
 #include <linux/psci.h>
+
+#include <asm/io.h>
 #include <asm/rsi.h>
 
 static struct realm_config config;
@@ -93,6 +95,16 @@ bool __arm64_is_protected_mmio(phys_addr_t base, size_t size)
 }
 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)
@@ -103,6 +115,9 @@ void __init arm64_rsi_init(void)
 		return;
 	prot_ns_shared = BIT(config.ipa_bits - 1);
 
+	if (arm64_ioremap_prot_hook_register(realm_ioremap_hook))
+		return;
+
 	arm64_rsi_setup_memory();
 
 	static_branch_enable(&rsi_present);
-- 
2.34.1