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Message-ID: <20250212171411.951874-2-suzuki.poulose@arm.com>
Date: Wed, 12 Feb 2025 17:14:11 +0000
From: Suzuki K Poulose <suzuki.poulose@....com>
To: will@...nel.org,
maz@...nel.org,
catalin.marinas@....com
Cc: linux-arm-kernel@...ts.infradead.org,
linux-kernel@...r.kernel.org,
gregkh@...uxfoundation.org,
aneesh.kumar@...nel.org,
steven.price@....com,
suzuki.poulose@....com,
Jean-Philippe Brucker <jean-philippe@...aro.org>,
Robin Murphy <robin.murphy@....com>,
Christoph Hellwig <hch@....de>,
Tom Lendacky <thomas.lendacky@....com>
Subject: [PATCH 1/1] arm64: realm: Use aliased addresses for device DMA to shared buffers
When a device performs DMA to a shared buffer using physical addresses,
(without Stage1 translation), the device must use the "{I}PA address" with the
top bit set in Realm. This is to make sure that a trusted device will be able
to write to shared buffers as well as the protected buffers. Thus, a Realm must
always program the full address including the "protection" bit, like AMD SME
encryption bits.
Add the support for this by providing arm64 version of the phys_to_dma(). We
cannot use the __sme_mask as it assumes the "encryption" always "sets a bit",
which is the opposite for CCA. i.e., "set a bit" for "decrypted" address. So,
move the common code that can be reused by all - i.e., add __phys_to_dma() and
__dma_to_phys() - and do the arch specific processing.
Please note that the VMM needs to similarly make sure that the SMMU Stage2 in
the Non-secure world is setup accordingly to map IPA at the unprotected alias.
Cc: Will Deacon <will@...nel.org>
Cc: Jean-Philippe Brucker <jean-philippe@...aro.org>
Cc: Catalin Marinas <catalin.marinas@....com>
Cc: Robin Murphy <robin.murphy@....com>
Cc: Steven Price <steven.price@....com>
Cc: Christoph Hellwig <hch@....de>
Cc: Tom Lendacky <thomas.lendacky@....com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
---
arch/arm64/Kconfig | 1 +
arch/arm64/include/asm/dma-direct.h | 38 +++++++++++++++++++++++++++++
include/linux/dma-direct.h | 35 +++++++++++++++++---------
3 files changed, 62 insertions(+), 12 deletions(-)
create mode 100644 arch/arm64/include/asm/dma-direct.h
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index fcdd0ed3eca8..7befe04106de 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -41,6 +41,7 @@ config ARM64
select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
select ARCH_HAS_NONLEAF_PMD_YOUNG if ARM64_HAFT
+ select ARCH_HAS_PHYS_TO_DMA
select ARCH_HAS_PTE_DEVMAP
select ARCH_HAS_PTE_SPECIAL
select ARCH_HAS_HW_PTE_YOUNG
diff --git a/arch/arm64/include/asm/dma-direct.h b/arch/arm64/include/asm/dma-direct.h
new file mode 100644
index 000000000000..37c3270542b8
--- /dev/null
+++ b/arch/arm64/include/asm/dma-direct.h
@@ -0,0 +1,38 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef __ASM_DMA_DIRECT_H
+#define __ASM_DMA_DIRECT_H
+
+#include <asm/pgtable-prot.h>
+
+static inline unsigned long addr_to_shared(unsigned long addr)
+{
+ if (is_realm_world())
+ addr |= prot_ns_shared;
+ return addr;
+}
+
+static inline unsigned long addr_to_private(unsigned long addr)
+{
+ if (is_realm_world())
+ addr &= prot_ns_shared - 1;
+ return addr;
+}
+
+static inline dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr)
+{
+ return __phys_to_dma(dev, paddr);
+}
+
+static inline dma_addr_t phys_to_dma_unencrypted(struct device *dev,
+ phys_addr_t paddr)
+{
+ return addr_to_shared(__phys_to_dma(dev, paddr));
+}
+#define phys_to_dma_unencrypted phys_to_dma_unencrypted
+
+static inline phys_addr_t dma_to_phys(struct device *dev, dma_addr_t dma_addr)
+{
+ return addr_to_private(__dma_to_phys(dev, dma_addr));
+}
+
+#endif /* __ASM_DMA_DIRECT_H */
diff --git a/include/linux/dma-direct.h b/include/linux/dma-direct.h
index d7e30d4f7503..3e9bf6ca640e 100644
--- a/include/linux/dma-direct.h
+++ b/include/linux/dma-direct.h
@@ -72,18 +72,36 @@ static inline dma_addr_t dma_range_map_max(const struct bus_dma_region *map)
return ret;
}
+static inline dma_addr_t __phys_to_dma(struct device *dev, phys_addr_t paddr)
+{
+ if (dev->dma_range_map)
+ return translate_phys_to_dma(dev, paddr);
+ return paddr;
+}
+
+static inline phys_addr_t __dma_to_phys(struct device *dev, dma_addr_t dma_addr)
+{
+ phys_addr_t paddr;
+
+ if (dev->dma_range_map)
+ paddr = translate_dma_to_phys(dev, dma_addr);
+ else
+ paddr = dma_addr;
+
+ return paddr;
+}
+
#ifdef CONFIG_ARCH_HAS_PHYS_TO_DMA
#include <asm/dma-direct.h>
#ifndef phys_to_dma_unencrypted
#define phys_to_dma_unencrypted phys_to_dma
#endif
#else
+
static inline dma_addr_t phys_to_dma_unencrypted(struct device *dev,
phys_addr_t paddr)
{
- if (dev->dma_range_map)
- return translate_phys_to_dma(dev, paddr);
- return paddr;
+ return __phys_to_dma(dev, paddr);
}
/*
@@ -94,19 +112,12 @@ static inline dma_addr_t phys_to_dma_unencrypted(struct device *dev,
*/
static inline dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr)
{
- return __sme_set(phys_to_dma_unencrypted(dev, paddr));
+ return __sme_set(__phys_to_dma(dev, paddr));
}
static inline phys_addr_t dma_to_phys(struct device *dev, dma_addr_t dma_addr)
{
- phys_addr_t paddr;
-
- if (dev->dma_range_map)
- paddr = translate_dma_to_phys(dev, dma_addr);
- else
- paddr = dma_addr;
-
- return __sme_clr(paddr);
+ return __sme_clr(__dma_to_phys(dev, dma_addr));
}
#endif /* !CONFIG_ARCH_HAS_PHYS_TO_DMA */
--
2.43.0
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