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 02/10] iommu/vt-d: Use per-device dma_ops
Date: Thu, 25 Jul 2019 15:18:03 +0800 [thread overview]
Message-ID: <bc831f88-5b19-7531-00aa-a7577dd5c1ac@linux.intel.com> (raw)
In-Reply-To: <20190725054413.GC24527@lst.de>
Hi Christoph,
On 7/25/19 1:44 PM, Christoph Hellwig wrote:
>> /* Check if the dev needs to go through non-identity map and unmap process.*/
>> static bool iommu_need_mapping(struct device *dev)
>> {
>> - int ret;
>> -
>> if (iommu_dummy(dev))
>> return false;
>>
>> - ret = identity_mapping(dev);
>> - if (ret) {
>> - u64 dma_mask = *dev->dma_mask;
>> -
>> - if (dev->coherent_dma_mask && dev->coherent_dma_mask < dma_mask)
>> - dma_mask = dev->coherent_dma_mask;
>> -
>> - if (dma_mask >= dma_get_required_mask(dev))
>> - return false;
>
> Don't we need to keep this bit so that we still allow the IOMMU
> to act if the device has a too small DMA mask to address all memory in
> the system, even if if it should otherwise be identity mapped?
>
This checking happens only when device is using an identity mapped
domain. If the device has a small DMA mask, swiotlb will be used for
high memory access.
This is supposed to be handled in dma_direct_map_page():
if (unlikely(!dma_direct_possible(dev, dma_addr, size)) &&
!swiotlb_map(dev, &phys, &dma_addr, size, dir, attrs)) {
report_addr(dev, dma_addr, size);
return DMA_MAPPING_ERROR;
}
Best regards,
Baolu
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next prev parent reply other threads:[~2019-07-25 7:18 UTC|newest]
Thread overview: 28+ 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 ` [PATCH v5 01/10] iommu/vt-d: Don't switch off swiotlb if use direct dma Lu Baolu
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 5:44 ` Christoph Hellwig
2019-07-25 7:18 ` Lu Baolu [this message]
2019-07-25 11:43 ` Christoph Hellwig
2019-07-26 1:56 ` Lu Baolu
2019-11-12 7:16 ` Christoph Hellwig
2019-11-13 2:50 ` Lu Baolu
2019-11-13 7:03 ` Christoph Hellwig
2019-11-13 9:53 ` Christoph Hellwig
2019-11-14 5:14 ` Lu Baolu
2019-11-14 8:14 ` 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 ` [PATCH v5 04/10] PCI: Add dev_is_untrusted helper Lu Baolu
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 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 11:49 ` Christoph Hellwig
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 ` [PATCH v5 08/10] iommu/vt-d: Check whether device requires bounce buffer 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 12:26 ` Steven Rostedt
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
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