Messages in this thread | ![/](/images/icornerl.gif) | | Subject | Re: [PATCH v5 06/10] swiotlb: Zero out bounce buffer for untrusted device | From | Lu Baolu <> | Date | Fri, 26 Jul 2019 10:21:36 +0800 |
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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
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