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From: Lu Baolu <baolu.lu@linux.intel.com>
To: Christoph Hellwig <hch@lst.de>
Cc: alan.cox@intel.com, Stefano Stabellini <sstabellini@kernel.org>,
	ashok.raj@intel.com, Jonathan Corbet <corbet@lwn.net>,
	pengfei.xu@intel.com, Ingo Molnar <mingo@redhat.com>,
	David Woodhouse <dwmw2@infradead.org>,
	kevin.tian@intel.com,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	mika.westerberg@linux.intel.com, Juergen Gross <jgross@suse.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
	jacob.jun.pan@intel.com, Robin Murphy <robin.murphy@arm.com>
Subject: Re: [PATCH v5 06/10] swiotlb: Zero out bounce buffer for untrusted device
Date: Fri, 26 Jul 2019 10:21:36 +0800	[thread overview]
Message-ID: <ed113403-6ae6-6730-0567-4c2eb8df94de@linux.intel.com> (raw)
In-Reply-To: <20190725114903.GB31065@lst.de>

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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WARNING: multiple messages have this Message-ID (diff)
From: Lu Baolu <baolu.lu@linux.intel.com>
To: Christoph Hellwig <hch@lst.de>
Cc: baolu.lu@linux.intel.com, David Woodhouse <dwmw2@infradead.org>,
	Joerg Roedel <joro@8bytes.org>,
	Bjorn Helgaas <bhelgaas@google.com>,
	ashok.raj@intel.com, jacob.jun.pan@intel.com, alan.cox@intel.com,
	kevin.tian@intel.com, mika.westerberg@linux.intel.com,
	Ingo Molnar <mingo@redhat.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	pengfei.xu@intel.com,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	Marek Szyprowski <m.szyprowski@samsung.com>,
	Robin Murphy <robin.murphy@arm.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	Juergen Gross <jgross@suse.com>,
	Stefano Stabellini <sstabellini@kernel.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 06/10] swiotlb: Zero out bounce buffer for untrusted device
Date: Fri, 26 Jul 2019 10:21:36 +0800	[thread overview]
Message-ID: <ed113403-6ae6-6730-0567-4c2eb8df94de@linux.intel.com> (raw)
In-Reply-To: <20190725114903.GB31065@lst.de>

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

  reply	other threads:[~2019-07-26  2:22 UTC|newest]

Thread overview: 58+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-25  3:17 [PATCH v5 00/10] iommu: Bounce page for untrusted devices Lu Baolu
2019-07-25  3:17 ` Lu Baolu
2019-07-25  3:17 ` [PATCH v5 01/10] iommu/vt-d: Don't switch off swiotlb if use direct dma Lu Baolu
2019-07-25  3:17   ` Lu Baolu
2019-07-25  5:41   ` Christoph Hellwig
2019-07-25  5:41     ` Christoph Hellwig
2019-07-25  3:17 ` [PATCH v5 02/10] iommu/vt-d: Use per-device dma_ops Lu Baolu
2019-07-25  3:17   ` Lu Baolu
2019-07-25  5:44   ` Christoph Hellwig
2019-07-25  5:44     ` Christoph Hellwig
2019-07-25  7:18     ` Lu Baolu
2019-07-25  7:18       ` Lu Baolu
2019-07-25 11:43       ` Christoph Hellwig
2019-07-25 11:43         ` Christoph Hellwig
2019-07-26  1:56         ` Lu Baolu
2019-07-26  1:56           ` Lu Baolu
2019-11-12  7:16           ` Christoph Hellwig
2019-11-12  7:16             ` Christoph Hellwig
2019-11-13  2:50             ` Lu Baolu
2019-11-13  2:50               ` Lu Baolu
2019-11-13  7:03               ` Christoph Hellwig
2019-11-13  7:03                 ` Christoph Hellwig
2019-11-13  9:53                 ` Christoph Hellwig
2019-11-13  9:53                   ` Christoph Hellwig
2019-11-14  5:14                   ` Lu Baolu
2019-11-14  5:14                     ` Lu Baolu
2019-11-14  8:14                     ` Christoph Hellwig
2019-11-14  8:14                       ` Christoph Hellwig
2019-11-15  0:57                       ` Lu Baolu
2019-11-20 10:44                         ` Christoph Hellwig
2019-07-25  3:17 ` [PATCH v5 03/10] iommu/vt-d: Cleanup after use per-device dma ops Lu Baolu
2019-07-25  3:17   ` Lu Baolu
2019-07-25  3:17 ` [PATCH v5 04/10] PCI: Add dev_is_untrusted helper Lu Baolu
2019-07-25  3:17   ` Lu Baolu
2019-07-25  5:44   ` Christoph Hellwig
2019-07-25  5:44     ` Christoph Hellwig
2019-07-25  3:17 ` [PATCH v5 05/10] swiotlb: Split size parameter to map/unmap APIs Lu Baolu
2019-07-25  3:17   ` Lu Baolu
2019-07-25 11:47   ` Christoph Hellwig
2019-07-25 11:47     ` Christoph Hellwig
2019-07-25  3:17 ` [PATCH v5 06/10] swiotlb: Zero out bounce buffer for untrusted device Lu Baolu
2019-07-25  3:17   ` Lu Baolu
2019-07-25 11:49   ` Christoph Hellwig
2019-07-25 11:49     ` Christoph Hellwig
2019-07-26  2:21     ` Lu Baolu [this message]
2019-07-26  2:21       ` Lu Baolu
2019-07-25  3:17 ` [PATCH v5 07/10] iommu: Add bounce page APIs Lu Baolu
2019-07-25  3:17   ` Lu Baolu
2019-07-25  3:17 ` [PATCH v5 08/10] iommu/vt-d: Check whether device requires bounce buffer Lu Baolu
2019-07-25  3:17   ` Lu Baolu
2019-07-25  3:17 ` [PATCH v5 09/10] iommu/vt-d: Add trace events for device dma map/unmap Lu Baolu
2019-07-25  3:17   ` Lu Baolu
2019-07-25 12:26   ` Steven Rostedt
2019-07-25 12:26     ` Steven Rostedt
2019-07-26  2:24     ` Lu Baolu
2019-07-26  2:24       ` Lu Baolu
2019-07-25  3:17 ` [PATCH v5 10/10] iommu/vt-d: Use bounce buffer for untrusted devices Lu Baolu
2019-07-25  3:17   ` Lu Baolu

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