From 9087c37584fb7d8315877bb55f85e4268cc0b4f4 Mon Sep 17 00:00:00 2001 From: Tom Lendacky Date: Wed, 10 Jul 2019 19:01:19 +0000 Subject: 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 Signed-off-by: Tom Lendacky Acked-by: Thomas Gleixner [hch: moved the force_dma_unencrypted declaration to dma-mapping.h, fold the s390 fix from Halil Pasic] Signed-off-by: Christoph Hellwig --- include/linux/dma-direct.h | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'include') diff --git a/include/linux/dma-direct.h b/include/linux/dma-direct.h index b7338702592a..adf993a3bd58 100644 --- a/include/linux/dma-direct.h +++ b/include/linux/dma-direct.h @@ -32,6 +32,15 @@ static inline bool dma_capable(struct device *dev, dma_addr_t addr, size_t size) } #endif /* !CONFIG_ARCH_HAS_PHYS_TO_DMA */ +#ifdef CONFIG_ARCH_HAS_FORCE_DMA_UNENCRYPTED +bool force_dma_unencrypted(struct device *dev); +#else +static inline bool force_dma_unencrypted(struct device *dev) +{ + return false; +} +#endif /* CONFIG_ARCH_HAS_FORCE_DMA_UNENCRYPTED */ + /* * If memory encryption is supported, phys_to_dma will set the memory encryption * bit in the DMA address, and dma_to_phys will clear it. The raw __phys_to_dma -- cgit v1.2.3 From b866455423e040813f113d8b87e8297778ee2014 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Tue, 16 Jul 2019 21:59:11 +0200 Subject: dma-mapping: add a dma_addressing_limited helper This helper returns if the device has issues addressing all present memory in the system. Signed-off-by: Christoph Hellwig --- include/linux/dma-mapping.h | 14 ++++++++++++++ 1 file changed, 14 insertions(+) (limited to 'include') diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index 8d13e28a8e07..e11b115dd0e4 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -679,6 +679,20 @@ static inline int dma_coerce_mask_and_coherent(struct device *dev, u64 mask) return dma_set_mask_and_coherent(dev, mask); } +/** + * dma_addressing_limited - return if the device is addressing limited + * @dev: device to check + * + * Return %true if the devices DMA mask is too small to address all memory in + * the system, else %false. Lack of addressing bits is the prime reason for + * bounce buffering, but might not be the only one. + */ +static inline bool dma_addressing_limited(struct device *dev) +{ + return min_not_zero(*dev->dma_mask, dev->bus_dma_mask) < + dma_get_required_mask(dev); +} + #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); -- cgit v1.2.3