From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joerg Roedel Subject: [PATCH 2/5] swiotlb: Add is_swiotlb_active() function Date: Thu, 31 Jan 2019 17:34:00 +0100 Message-ID: <20190131163403.11363-3-joro@8bytes.org> References: <20190131163403.11363-1-joro@8bytes.org> Return-path: In-Reply-To: <20190131163403.11363-1-joro@8bytes.org> Sender: linux-kernel-owner@vger.kernel.org To: "Michael S . Tsirkin" , Jason Wang , Konrad Rzeszutek Wilk , Christoph Hellwig Cc: Jens Axboe , virtualization@lists.linux-foundation.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, jfehlig@suse.com, jon.grimm@amd.com, brijesh.singh@amd.com, joro@8bytes.org, jroedel@suse.de, Thomas.Lendacky@amd.com List-Id: iommu@lists.linux-foundation.org From: Joerg Roedel This function will be used from dma_direct code to determine the maximum segment size of a dma mapping. Reviewed-by: Konrad Rzeszutek Wilk Reviewed-by: Christoph Hellwig Signed-off-by: Joerg Roedel --- include/linux/swiotlb.h | 6 ++++++ kernel/dma/swiotlb.c | 9 +++++++++ 2 files changed, 15 insertions(+) diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h index 1c22d96e1742..e9e786b4b598 100644 --- a/include/linux/swiotlb.h +++ b/include/linux/swiotlb.h @@ -63,6 +63,7 @@ extern void swiotlb_tbl_sync_single(struct device *hwdev, extern int swiotlb_dma_supported(struct device *hwdev, u64 mask); size_t swiotlb_max_mapping_size(struct device *dev); +bool is_swiotlb_active(void); #ifdef CONFIG_SWIOTLB extern enum swiotlb_force swiotlb_force; @@ -100,6 +101,11 @@ static inline size_t swiotlb_max_mapping_size(struct device *dev) { return SIZE_MAX; } + +static inline bool is_swiotlb_active(void) +{ + return false; +} #endif /* CONFIG_SWIOTLB */ extern void swiotlb_print_info(void); diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c index 9cb21259cb0b..c873f9cc2146 100644 --- a/kernel/dma/swiotlb.c +++ b/kernel/dma/swiotlb.c @@ -667,3 +667,12 @@ size_t swiotlb_max_mapping_size(struct device *dev) { return ((size_t)1 << IO_TLB_SHIFT) * IO_TLB_SEGSIZE; } + +bool is_swiotlb_active(void) +{ + /* + * When SWIOTLB is initialized, even if io_tlb_start points to physical + * address zero, io_tlb_end surely doesn't. + */ + return io_tlb_end != 0; +} -- 2.17.1