From: Ram Pai <linuxram@us.ibm.com>
To: linux-kernel@vger.kernel.org
Cc: andmike@us.ibm.com, sukadev@linux.vnet.ibm.com,
b.zolnierkie@samsung.com, jasowang@redhat.com, aik@linux.ibm.com,
linuxram@us.ibm.com, mdroth@linux.vnet.ibm.com,
virtualization@lists.linux-foundation.org,
iommu@lists.linux-foundation.org, paul.burton@mips.com,
robin.murphy@arm.com, m.szyprowski@samsung.com,
linuxppc-dev@lists.ozlabs.org, hch@lst.de,
david@gibson.dropbear.id.au
Subject: [PATCH 1/2] dma-mapping: Add dma_addr_is_phys_addr()
Date: Fri, 11 Oct 2019 18:25:18 -0700 [thread overview]
Message-ID: <1570843519-8696-2-git-send-email-linuxram@us.ibm.com> (raw)
In-Reply-To: <1570843519-8696-1-git-send-email-linuxram@us.ibm.com>
From: Thiago Jung Bauermann <bauerman@linux.ibm.com>
In order to safely use the DMA API, virtio needs to know whether DMA
addresses are in fact physical addresses and for that purpose,
dma_addr_is_phys_addr() is introduced.
cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
cc: David Gibson <david@gibson.dropbear.id.au>
cc: Michael Ellerman <mpe@ellerman.id.au>
cc: Paul Mackerras <paulus@ozlabs.org>
cc: Michael Roth <mdroth@linux.vnet.ibm.com>
cc: Alexey Kardashevskiy <aik@linux.ibm.com>
cc: Paul Burton <paul.burton@mips.com>
cc: Robin Murphy <robin.murphy@arm.com>
cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
cc: Marek Szyprowski <m.szyprowski@samsung.com>
cc: Christoph Hellwig <hch@lst.de>
Suggested-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Ram Pai <linuxram@us.ibm.com>
Signed-off-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
---
arch/powerpc/include/asm/dma-mapping.h | 21 +++++++++++++++++++++
arch/powerpc/platforms/pseries/Kconfig | 1 +
include/linux/dma-mapping.h | 20 ++++++++++++++++++++
kernel/dma/Kconfig | 3 +++
4 files changed, 45 insertions(+)
diff --git a/arch/powerpc/include/asm/dma-mapping.h b/arch/powerpc/include/asm/dma-mapping.h
index 565d6f7..f92c0a4b 100644
--- a/arch/powerpc/include/asm/dma-mapping.h
+++ b/arch/powerpc/include/asm/dma-mapping.h
@@ -5,6 +5,8 @@
#ifndef _ASM_DMA_MAPPING_H
#define _ASM_DMA_MAPPING_H
+#include <asm/svm.h>
+
static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
{
/* We don't handle the NULL dev case for ISA for now. We could
@@ -15,4 +17,23 @@ static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
return NULL;
}
+#ifdef CONFIG_ARCH_HAS_DMA_ADDR_IS_PHYS_ADDR
+/**
+ * dma_addr_is_phys_addr - check whether a device DMA address is a physical
+ * address
+ * @dev: device to check
+ *
+ * Returns %true if any DMA address for this device happens to also be a valid
+ * physical address (not necessarily of the same page).
+ */
+static inline bool dma_addr_is_phys_addr(struct device *dev)
+{
+ /*
+ * Secure guests always use the SWIOTLB, therefore DMA addresses are
+ * actually the physical address of the bounce buffer.
+ */
+ return is_secure_guest();
+}
+#endif
+
#endif /* _ASM_DMA_MAPPING_H */
diff --git a/arch/powerpc/platforms/pseries/Kconfig b/arch/powerpc/platforms/pseries/Kconfig
index 9e35cdd..0108150 100644
--- a/arch/powerpc/platforms/pseries/Kconfig
+++ b/arch/powerpc/platforms/pseries/Kconfig
@@ -152,6 +152,7 @@ config PPC_SVM
select SWIOTLB
select ARCH_HAS_MEM_ENCRYPT
select ARCH_HAS_FORCE_DMA_UNENCRYPTED
+ select ARCH_HAS_DMA_ADDR_IS_PHYS_ADDR
help
There are certain POWER platforms which support secure guests using
the Protected Execution Facility, with the help of an Ultravisor
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index f7d1eea..6df5664 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -693,6 +693,26 @@ static inline bool dma_addressing_limited(struct device *dev)
dma_get_required_mask(dev);
}
+#ifndef CONFIG_ARCH_HAS_DMA_ADDR_IS_PHYS_ADDR
+/**
+ * dma_addr_is_phys_addr - check whether a device DMA address is a physical
+ * address
+ * @dev: device to check
+ *
+ * Returns %true if any DMA address for this device happens to also be a valid
+ * physical address (not necessarily of the same page).
+ */
+static inline bool dma_addr_is_phys_addr(struct device *dev)
+{
+ /*
+ * Except in very specific setups, DMA addresses exist in a different
+ * address space from CPU physical addresses and cannot be directly used
+ * to reference system memory.
+ */
+ return false;
+}
+#endif
+
#ifdef CONFIG_ARCH_HAS_SETUP_DMA_OPS
void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
const struct iommu_ops *iommu, bool coherent);
diff --git a/kernel/dma/Kconfig b/kernel/dma/Kconfig
index 9decbba..6209b46 100644
--- a/kernel/dma/Kconfig
+++ b/kernel/dma/Kconfig
@@ -51,6 +51,9 @@ config ARCH_HAS_DMA_MMAP_PGPROT
config ARCH_HAS_FORCE_DMA_UNENCRYPTED
bool
+config ARCH_HAS_DMA_ADDR_IS_PHYS_ADDR
+ bool
+
config DMA_NONCOHERENT_CACHE_SYNC
bool
--
1.8.3.1
next prev parent reply other threads:[~2019-10-12 1:31 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-12 1:25 [PATCH 0/2] virtio: Support encrypted memory on powerpc secure guests Ram Pai
2019-10-12 1:25 ` Ram Pai [this message]
2019-10-12 1:25 ` [PATCH 2/2] virtio_ring: Use DMA API if memory is encrypted Ram Pai
2019-10-14 4:52 ` David Gibson
2019-10-15 7:35 ` Christoph Hellwig
2019-10-16 7:55 ` Ram Pai
2019-10-17 2:33 ` Jason Wang
2019-10-21 8:36 ` David Gibson
2019-10-14 4:51 ` [PATCH 1/2] dma-mapping: Add dma_addr_is_phys_addr() David Gibson
2019-10-14 10:29 ` Robin Murphy
2019-10-15 7:30 ` Ram Pai
2019-10-15 7:31 ` Christoph Hellwig
2019-10-12 1:36 ` [PATCH 0/2] virtio: Support encrypted memory on powerpc secure guests Ram Pai
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