linux-kernel - [PATCH v5 11/19] arm64: rsi: Map unprotected MMIO as decrypted

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Message-Id: <20240819131924.372366-12-steven.price@arm.com>
Date: Mon, 19 Aug 2024 14:19:16 +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>,
	Gavin Shan <gshan@...hat.com>,
	Shanker Donthineni <sdonthineni@...dia.com>,
	Alper Gun <alpergun@...gle.com>
Subject: [PATCH v5 11/19] 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.

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 +++++++++++++++
 arch/arm64/mm/mmu.c     |  2 +-
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/rsi.c b/arch/arm64/kernel/rsi.c
index 381a5b9a5333..672dd6862298 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>
 
 struct realm_config config;
@@ -93,6 +95,16 @@ bool arm64_rsi_is_protected_mmio(phys_addr_t base, size_t size)
 }
 EXPORT_SYMBOL(arm64_rsi_is_protected_mmio);
 
+static int realm_ioremap_hook(phys_addr_t phys, size_t size, pgprot_t *prot)
+{
+	if (arm64_rsi_is_protected_mmio(phys, size))
+		*prot = pgprot_encrypted(*prot);
+	else
+		*prot = pgprot_decrypted(*prot);
+
+	return 0;
+}
+
 void __init arm64_rsi_init(void)
 {
 	/*
@@ -107,6 +119,9 @@ 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;
+
 	static_branch_enable(&rsi_present);
 }
 
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 06b66c23c124..0c2fa35beca0 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -1207,7 +1207,7 @@ void set_fixmap_io(enum fixed_addresses idx, phys_addr_t phys)
 	else
 		prot = pgprot_encrypted(prot);
 
-	__set_fixmap(idx, phys, prot);
+	__set_fixmap(idx, phys & PAGE_MASK, prot);
 }
 
 int pud_set_huge(pud_t *pudp, phys_addr_t phys, pgprot_t prot)
-- 
2.34.1