[PATCH] arm64: mte: Map hotplugged memory as Normal Tagged

[Catalin Marinas <catalin.marinas@xxxxxxx>]

In a system supporting MTE, the linear map must allow reading/writing
allocation tags by setting the memory type as Normal Tagged. Currently,
this is only handled for memory present at boot. Hotplugged memory uses
Normal non-Tagged memory.

Introduce pgprot_mhp() for hotplugged memory and use it in
add_memory_resource(). The arm64 code maps pgprot_mhp() to
pgprot_tagged().

Note that ZONE_DEVICE memory should not be mapped as Tagged and
therefore setting the memory type in arch_add_memory() is not feasible.

Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Fixes: 0178dc761368 ("arm64: mte: Use Normal Tagged attributes for the linear map")
Reported-by: Patrick Daly <pdaly@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/1614745263-27827-1-git-send-email-pdaly@xxxxxxxxxxxxxx
Cc: <stable@xxxxxxxxxxxxxxx> # 5.10.x
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
---

Patrick, could you please give this patch a try on your platform? Thanks.

 arch/arm64/include/asm/pgtable-prot.h | 1 -
 arch/arm64/include/asm/pgtable.h      | 3 +++
 arch/arm64/mm/mmu.c                   | 3 ++-
 include/linux/pgtable.h               | 4 ++++
 mm/memory_hotplug.c                   | 2 +-
 5 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/include/asm/pgtable-prot.h b/arch/arm64/include/asm/pgtable-prot.h
index 046be789fbb4..9a65fb528110 100644
--- a/arch/arm64/include/asm/pgtable-prot.h
+++ b/arch/arm64/include/asm/pgtable-prot.h
@@ -66,7 +66,6 @@ extern bool arm64_use_ng_mappings;
 #define _PAGE_DEFAULT		(_PROT_DEFAULT | PTE_ATTRINDX(MT_NORMAL))
 
 #define PAGE_KERNEL		__pgprot(PROT_NORMAL)
-#define PAGE_KERNEL_TAGGED	__pgprot(PROT_NORMAL_TAGGED)
 #define PAGE_KERNEL_RO		__pgprot((PROT_NORMAL & ~PTE_WRITE) | PTE_RDONLY)
 #define PAGE_KERNEL_ROX		__pgprot((PROT_NORMAL & ~(PTE_WRITE | PTE_PXN)) | PTE_RDONLY)
 #define PAGE_KERNEL_EXEC	__pgprot(PROT_NORMAL & ~PTE_PXN)
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index e17b96d0e4b5..47027796c2f9 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -486,6 +486,9 @@ static inline pmd_t pmd_mkdevmap(pmd_t pmd)
 	__pgprot_modify(prot, PTE_ATTRINDX_MASK, PTE_ATTRINDX(MT_NORMAL_NC) | PTE_PXN | PTE_UXN)
 #define pgprot_device(prot) \
 	__pgprot_modify(prot, PTE_ATTRINDX_MASK, PTE_ATTRINDX(MT_DEVICE_nGnRE) | PTE_PXN | PTE_UXN)
+#define pgprot_tagged(prot) \
+	__pgprot_modify(prot, PTE_ATTRINDX_MASK, PTE_ATTRINDX(MT_NORMAL_TAGGED))
+#define pgprot_mhp	pgprot_tagged
 /*
  * DMA allocations for non-coherent devices use what the Arm architecture calls
  * "Normal non-cacheable" memory, which permits speculation, unaligned accesses
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 3802cfbdd20d..9c8aa1b44cd5 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -512,7 +512,8 @@ static void __init map_mem(pgd_t *pgdp)
 		 * if MTE is present. Otherwise, it has the same attributes as
 		 * PAGE_KERNEL.
 		 */
-		__map_memblock(pgdp, start, end, PAGE_KERNEL_TAGGED, flags);
+		__map_memblock(pgdp, start, end, pgprot_tagged(PAGE_KERNEL),
+			       flags);
 	}
 
 	/*
diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index cdfc4e9f253e..5e772392a379 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -904,6 +904,10 @@ static inline void ptep_modify_prot_commit(struct vm_area_struct *vma,
 #define pgprot_device pgprot_noncached
 #endif
 
+#ifndef pgprot_mhp
+#define pgprot_mhp(prot)	(prot)
+#endif
+
 #ifdef CONFIG_MMU
 #ifndef pgprot_modify
 #define pgprot_modify pgprot_modify
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 5ba51a8bdaeb..0cdbbfbc5757 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1072,7 +1072,7 @@ static int online_memory_block(struct memory_block *mem, void *arg)
  */
 int __ref add_memory_resource(int nid, struct resource *res, mhp_t mhp_flags)
 {
-	struct mhp_params params = { .pgprot = PAGE_KERNEL };
+	struct mhp_params params = { .pgprot = pgprot_mhp(PAGE_KERNEL) };
 	u64 start, size;
 	bool new_node = false;
 	int ret;