linux-kernel - Re: [PATCH v9 1/5] swiotlb: Split size parameter to map/unmap APIs

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Date:   Wed, 11 Sep 2019 14:16:07 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Cc:     baolu.lu@...ux.intel.com, David Woodhouse <dwmw2@...radead.org>,
        Joerg Roedel <joro@...tes.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Christoph Hellwig <hch@....de>, ashok.raj@...el.com,
        jacob.jun.pan@...el.com, alan.cox@...el.com, kevin.tian@...el.com,
        mika.westerberg@...ux.intel.com, Ingo Molnar <mingo@...hat.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        pengfei.xu@...el.com, Marek Szyprowski <m.szyprowski@...sung.com>,
        Robin Murphy <robin.murphy@....com>,
        Jonathan Corbet <corbet@....net>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Juergen Gross <jgross@...e.com>,
        Stefano Stabellini <sstabellini@...nel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v9 1/5] swiotlb: Split size parameter to map/unmap APIs

Hi,

On 9/10/19 11:15 PM, Konrad Rzeszutek Wilk wrote:
> On Fri, Sep 06, 2019 at 02:14:48PM +0800, Lu Baolu wrote:
>> This splits the size parameter to swiotlb_tbl_map_single() and
>> swiotlb_tbl_unmap_single() into an alloc_size and a mapping_size
>> parameter, where the latter one is rounded up to the iommu page
>> size.
> It does a bit more too. You have the WARN_ON. Can you make it be
> more  verbose (as in details of which device requested it) and also use printk_once or so please?

How about this change?

diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index 89066efa3840..22a7848caca3 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -466,8 +466,11 @@ phys_addr_t swiotlb_tbl_map_single(struct device 
*hwdev,
                 pr_warn_once("%s is active and system is using DMA 
bounce buffers\n",
                              sme_active() ? "SME" : "SEV");

-       if (WARN_ON(mapping_size > alloc_size))
+       if (mapping_size > alloc_size) {
+               dev_warn_once(hwdev, "Invalid sizes (mapping: %zd bytes, 
alloc: %zd bytes)",
+                             mapping_size, alloc_size);
                 return (phys_addr_t)DMA_MAPPING_ERROR;
+       }

         mask = dma_get_seg_boundary(hwdev);

@@ -584,9 +587,6 @@ void swiotlb_tbl_unmap_single(struct device *hwdev, 
phys_addr_t tlb_addr,
         int index = (tlb_addr - io_tlb_start) >> IO_TLB_SHIFT;
         phys_addr_t orig_addr = io_tlb_orig_addr[index];

-       if (WARN_ON(mapping_size > alloc_size))
-               return;
-
         /*
          * First, sync the memory before unmapping the entry
          */

Best regards,
Baolu