[RFC PATCH V3 08/11] swiotlb: Add bounce buffer remap address setting function
From: Tianyu Lan <hidden>
Date: 2021-05-30 15:07:23
Also in:
linux-arch, linux-hyperv, linux-iommu, linux-scsi, lkml, xen-devel
Subsystem:
dma mapping helpers, the rest · Maintainers:
Marek Szyprowski, Linus Torvalds
From: Tianyu Lan <redacted> For Hyper-V isolation VM with AMD SEV SNP, the bounce buffer(shared memory) needs to be accessed via extra address space(e.g address above bit39). Hyper-V code may remap extra address space outside of swiotlb. swiotlb_ bounce() needs to use remap virtual address to copy data from/to bounce buffer. Add new interface swiotlb_set_bounce_remap() to do that. Signed-off-by: Tianyu Lan <redacted> --- include/linux/swiotlb.h | 5 +++++ kernel/dma/swiotlb.c | 14 +++++++++++++- 2 files changed, 18 insertions(+), 1 deletion(-)
diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
index 216854a5e513..43f53cf52f48 100644
--- a/include/linux/swiotlb.h
+++ b/include/linux/swiotlb.h@@ -113,8 +113,13 @@ unsigned int swiotlb_max_segment(void); size_t swiotlb_max_mapping_size(struct device *dev); bool is_swiotlb_active(void); void __init swiotlb_adjust_size(unsigned long size); +void swiotlb_set_bounce_remap(unsigned char *vaddr); #else #define swiotlb_force SWIOTLB_NO_FORCE +static inline void swiotlb_set_bounce_remap(unsigned char *vaddr) +{ +} + static inline bool is_swiotlb_buffer(phys_addr_t paddr) { return false;
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index 8ca7d505d61c..fbc827ab5fb4 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c@@ -70,6 +70,7 @@ struct io_tlb_mem *io_tlb_default_mem; * not be bounced (unless SWIOTLB_FORCE is set). */ static unsigned int max_segment; +static unsigned char *swiotlb_bounce_remap_addr; static unsigned long default_nslabs = IO_TLB_DEFAULT_SIZE >> IO_TLB_SHIFT;
@@ -334,6 +335,11 @@ void __init swiotlb_exit(void) io_tlb_default_mem = NULL; } +void swiotlb_set_bounce_remap(unsigned char *vaddr) +{ + swiotlb_bounce_remap_addr = vaddr; +} + /* * Bounce: copy the swiotlb buffer from or back to the original dma location */
@@ -345,7 +351,13 @@ static void swiotlb_bounce(struct device *dev, phys_addr_t tlb_addr, size_t size phys_addr_t orig_addr = mem->slots[index].orig_addr; size_t alloc_size = mem->slots[index].alloc_size; unsigned long pfn = PFN_DOWN(orig_addr); - unsigned char *vaddr = phys_to_virt(tlb_addr); + unsigned char *vaddr; + + if (swiotlb_bounce_remap_addr) + vaddr = swiotlb_bounce_remap_addr + tlb_addr - + io_tlb_default_mem->start; + else + vaddr = phys_to_virt(tlb_addr); if (orig_addr == INVALID_PHYS_ADDR) return;
--
2.25.1