Hi, On 7/25/19 7:49 PM, Christoph Hellwig wrote:
index 43c88626a1f3..edc84a00b9f9 100644 --- a/kernel/dma/swiotlb.c +++ b/kernel/dma/swiotlb.c @@ -35,6 +35,7 @@ #include <linux/scatterlist.h> #include <linux/mem_encrypt.h> #include <linux/set_memory.h> +#include <linux/pci.h> #ifdef CONFIG_DEBUG_FS #include <linux/debugfs.h> #endif @@ -562,6 +563,11 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev, */ for (i = 0; i < nslots; i++) io_tlb_orig_addr[index+i] = orig_addr + (i << IO_TLB_SHIFT); + + /* Zero out the bounce buffer if the consumer is untrusted. */ + if (dev_is_untrusted(hwdev)) + memset(phys_to_virt(tlb_addr), 0, alloc_size);Hmm. Maybe we need to move the untrusted flag to struct device? Directly poking into the pci_dev from swiotlb is a bit of a layering violation.
Yes. We can consider this. But I tend to think that it's worth of a separated series. That's a reason why I defined dev_is_untrusted(). This helper keeps the caller same when moving the untrusted flag.
+ if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC) && (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL)) swiotlb_bounce(orig_addr, tlb_addr, mapping_size, DMA_TO_DEVICE);Also for the case where we bounce here we only need to zero the padding (if there is any), so I think we could optimize this a bit.
Yes. There's duplication here. Best regards, Baolu
