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authorTom Lendacky <thomas.lendacky@amd.com>2019-07-10 19:01:19 +0000
committerChristoph Hellwig <hch@lst.de>2019-07-16 22:15:46 +0200
commit9087c37584fb7d8315877bb55f85e4268cc0b4f4 (patch)
tree11f256332491057cf19db8aa447d44465bec79da /arch/s390
parent9637d517347e80ee2fe1c5d8ce45ba1b88d8b5cd (diff)
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dma-direct: Force unencrypted DMA under SME for certain DMA masks
If a device doesn't support DMA to a physical address that includes the encryption bit (currently bit 47, so 48-bit DMA), then the DMA must occur to unencrypted memory. SWIOTLB is used to satisfy that requirement if an IOMMU is not active (enabled or configured in passthrough mode). However, commit fafadcd16595 ("swiotlb: don't dip into swiotlb pool for coherent allocations") modified the coherent allocation support in SWIOTLB to use the DMA direct coherent allocation support. When an IOMMU is not active, this resulted in dma_alloc_coherent() failing for devices that didn't support DMA addresses that included the encryption bit. Addressing this requires changes to the force_dma_unencrypted() function in kernel/dma/direct.c. Since the function is now non-trivial and SME/SEV specific, update the DMA direct support to add an arch override for the force_dma_unencrypted() function. The arch override is selected when CONFIG_AMD_MEM_ENCRYPT is set. The arch override function resides in the arch/x86/mm/mem_encrypt.c file and forces unencrypted DMA when either SEV is active or SME is active and the device does not support DMA to physical addresses that include the encryption bit. Fixes: fafadcd16595 ("swiotlb: don't dip into swiotlb pool for coherent allocations") Suggested-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com> Acked-by: Thomas Gleixner <tglx@linutronix.de> [hch: moved the force_dma_unencrypted declaration to dma-mapping.h, fold the s390 fix from Halil Pasic] Signed-off-by: Christoph Hellwig <hch@lst.de>
Diffstat (limited to 'arch/s390')
-rw-r--r--arch/s390/Kconfig1
-rw-r--r--arch/s390/mm/init.c7
2 files changed, 7 insertions, 1 deletions
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 5d8570ed6cab..a4ad2733eedf 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -189,6 +189,7 @@ config S390
select VIRT_CPU_ACCOUNTING
select ARCH_HAS_SCALED_CPUTIME
select HAVE_NMI
+ select ARCH_HAS_FORCE_DMA_UNENCRYPTED
select SWIOTLB
select GENERIC_ALLOCATOR
diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
index f0bee6af3960..78c319c5ce48 100644
--- a/arch/s390/mm/init.c
+++ b/arch/s390/mm/init.c
@@ -30,7 +30,7 @@
#include <linux/export.h>
#include <linux/cma.h>
#include <linux/gfp.h>
-#include <linux/dma-mapping.h>
+#include <linux/dma-direct.h>
#include <asm/processor.h>
#include <linux/uaccess.h>
#include <asm/pgtable.h>
@@ -161,6 +161,11 @@ bool sev_active(void)
return is_prot_virt_guest();
}
+bool force_dma_unencrypted(struct device *dev)
+{
+ return sev_active();
+}
+
/* protected virtualization */
static void pv_init(void)
{