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Message-Id: <20240819131924.372366-3-steven.price@arm.com>
Date: Mon, 19 Aug 2024 14:19:07 +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 02/19] arm64: mm: Add confidential computing hook to ioremap_prot()
From: Will Deacon <will@...nel.org>
Confidential Computing environments such as pKVM and Arm's CCA
distinguish between shared (i.e. emulated) and private (i.e. assigned)
MMIO regions.
Introduce a hook into our implementation of ioremap_prot() so that MMIO
regions can be shared if necessary.
Signed-off-by: Will Deacon <will@...nel.org>
Signed-off-by: Steven Price <steven.price@....com>
---
Patch 'borrowed' from Will's series for pKVM:
https://lore.kernel.org/r/20240730151113.1497-6-will%40kernel.org
---
arch/arm64/include/asm/io.h | 4 ++++
arch/arm64/mm/ioremap.c | 23 ++++++++++++++++++++++-
2 files changed, 26 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/include/asm/io.h b/arch/arm64/include/asm/io.h
index 41fd90895dfc..1ada23a6ec19 100644
--- a/arch/arm64/include/asm/io.h
+++ b/arch/arm64/include/asm/io.h
@@ -271,6 +271,10 @@ __iowrite64_copy(void __iomem *to, const void *from, size_t count)
* I/O memory mapping functions.
*/
+typedef int (*ioremap_prot_hook_t)(phys_addr_t phys_addr, size_t size,
+ pgprot_t *prot);
+int arm64_ioremap_prot_hook_register(const ioremap_prot_hook_t hook);
+
#define ioremap_prot ioremap_prot
#define _PAGE_IOREMAP PROT_DEVICE_nGnRE
diff --git a/arch/arm64/mm/ioremap.c b/arch/arm64/mm/ioremap.c
index 269f2f63ab7d..6cc0b7e7eb03 100644
--- a/arch/arm64/mm/ioremap.c
+++ b/arch/arm64/mm/ioremap.c
@@ -3,10 +3,22 @@
#include <linux/mm.h>
#include <linux/io.h>
+static ioremap_prot_hook_t ioremap_prot_hook;
+
+int arm64_ioremap_prot_hook_register(ioremap_prot_hook_t hook)
+{
+ if (WARN_ON(ioremap_prot_hook))
+ return -EBUSY;
+
+ ioremap_prot_hook = hook;
+ return 0;
+}
+
void __iomem *ioremap_prot(phys_addr_t phys_addr, size_t size,
unsigned long prot)
{
unsigned long last_addr = phys_addr + size - 1;
+ pgprot_t pgprot = __pgprot(prot);
/* Don't allow outside PHYS_MASK */
if (last_addr & ~PHYS_MASK)
@@ -16,7 +28,16 @@ void __iomem *ioremap_prot(phys_addr_t phys_addr, size_t size,
if (WARN_ON(pfn_is_map_memory(__phys_to_pfn(phys_addr))))
return NULL;
- return generic_ioremap_prot(phys_addr, size, __pgprot(prot));
+ /*
+ * If a hook is registered (e.g. for confidential computing
+ * purposes), call that now and barf if it fails.
+ */
+ if (unlikely(ioremap_prot_hook) &&
+ WARN_ON(ioremap_prot_hook(phys_addr, size, &pgprot))) {
+ return NULL;
+ }
+
+ return generic_ioremap_prot(phys_addr, size, pgprot);
}
EXPORT_SYMBOL(ioremap_prot);
--
2.34.1
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