[PATCH kernel 5/5] vfio/spapr_tce: Advertise and allow a huge DMA windows at 4GB
From: Alexey Kardashevskiy <hidden>
Date: 2020-02-18 07:49:40
Subsystem:
ibm power vfio support, the rest, vfio driver · Maintainers:
Timothy Pearson, Linus Torvalds, Alex Williamson
So far the only option for a big 64big DMA window was a window located at 0x800.0000.0000.0000 (1<<59) which creates problems for devices supporting smaller DMA masks. This exploits a POWER9 PHB option to allow the second DMA window to map at 0 and advertises it with a 4GB offset to avoid overlap with the default 32bit window. Signed-off-by: Alexey Kardashevskiy <redacted> --- include/uapi/linux/vfio.h | 2 ++ drivers/vfio/vfio_iommu_spapr_tce.c | 10 ++++++++-- 2 files changed, 10 insertions(+), 2 deletions(-)
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 9e843a147ead..c7f89d47335a 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h@@ -831,9 +831,11 @@ struct vfio_iommu_spapr_tce_info { __u32 argsz; __u32 flags; #define VFIO_IOMMU_SPAPR_INFO_DDW (1 << 0) /* DDW supported */ +#define VFIO_IOMMU_SPAPR_INFO_DDW_START (1 << 1) /* DDW offset */ __u32 dma32_window_start; /* 32 bit window start (bytes) */ __u32 dma32_window_size; /* 32 bit window size (bytes) */ struct vfio_iommu_spapr_tce_ddw_info ddw; + __u64 dma64_window_start; }; #define VFIO_IOMMU_SPAPR_TCE_GET_INFO _IO(VFIO_TYPE, VFIO_BASE + 12)
diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c
index 16b3adc508db..4f22be3c4aa2 100644
--- a/drivers/vfio/vfio_iommu_spapr_tce.c
+++ b/drivers/vfio/vfio_iommu_spapr_tce.c@@ -691,7 +691,7 @@ static long tce_iommu_create_window(struct tce_container *container, container->tables[num] = tbl; /* Return start address assigned by platform in create_table() */ - *start_addr = tbl->it_offset << tbl->it_page_shift; + *start_addr = tbl->it_dmaoff << tbl->it_page_shift; return 0;
@@ -842,7 +842,13 @@ static long tce_iommu_ioctl(void *iommu_data, info.ddw.levels = table_group->max_levels; } - ddwsz = offsetofend(struct vfio_iommu_spapr_tce_info, ddw); + ddwsz = offsetofend(struct vfio_iommu_spapr_tce_info, + dma64_window_start); + + if (info.argsz >= ddwsz) { + info.flags |= VFIO_IOMMU_SPAPR_INFO_DDW_START; + info.dma64_window_start = table_group->tce64_start; + } if (info.argsz >= ddwsz) minsz = ddwsz;
--
2.17.1