[Resend RFC PATCH V2 09/12] swiotlb: Add bounce buffer remap address setting function
From: Tianyu Lan <hidden>
Date: 2021-04-14 14:51:21
Also in:
linux-arch, linux-iommu, linux-scsi, lkml, netdev
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 | 13 ++++++++++++- 2 files changed, 17 insertions(+), 1 deletion(-)
diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
index d9c9fc9ca5d2..3ccd08116683 100644
--- a/include/linux/swiotlb.h
+++ b/include/linux/swiotlb.h@@ -82,8 +82,13 @@ 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 new_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 7c42df6e6100..5fd2db6aa149 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c@@ -94,6 +94,7 @@ static unsigned int io_tlb_index; * not be bounced (unless SWIOTLB_FORCE is set). */ static unsigned int max_segment; +static unsigned char *swiotlb_bounce_remap_addr; /* * We need to save away the original address corresponding to a mapped entry
@@ -421,6 +422,11 @@ void __init swiotlb_exit(void) swiotlb_cleanup(); } +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 */
@@ -428,7 +434,12 @@ static void swiotlb_bounce(phys_addr_t orig_addr, phys_addr_t tlb_addr, size_t size, enum dma_data_direction dir) { 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_start; + else + vaddr = phys_to_virt(tlb_addr); if (PageHighMem(pfn_to_page(pfn))) { /* The buffer does not have a mapping. Map it in and copy */
--
2.25.1