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Message-ID: <383509cb-ae33-e0c4-1c06-8b162acdb555@codeaurora.org>
Date: Thu, 13 Apr 2017 09:29:37 -0500
From: Shanker Donthineni <shankerd@...eaurora.org>
To: Robin Murphy <robin.murphy@....com>,
Nate Watterson <nwatters@...eaurora.org>,
Joerg Roedel <joro@...tes.org>,
iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] iommu/dma: Setup iova_domain granule for IOMMU_DMA_MSI
cookies
Hi Robin,
I tested your changes and the device pass-through feature works fine on QDF2400 server platform. Maybe Nate comments on the patch contents but it fixes the problem.
@@ -317,13 +317,13 @@ static void iommu_dma_free_iova(struct iommu_dma_cookie *cookie,
dma_addr_t iova, size_t size)
{
struct iova_domain *iovad = &cookie->iovad;
- unsigned long shift = iova_shift(iovad);
/* The MSI case is only ever cleaning up its most recent allocation */
if (cookie->type == IOMMU_DMA_MSI_COOKIE)
cookie->msi_iova -= size;
else
- free_iova_fast(iovad, iova >> shift, size >> shift);
+ free_iova_fast(iovad, iova_pfn(iovad, iova),
+ size >> iova_shift(iovad));
}
static void __iommu_dma_unmap(struct iommu_domain *domain, dma_addr_t dma_addr,
@@ -538,11 +538,14 @@ static dma_addr_t __iommu_dma_map(struct device *dev, phys_addr_t phys,
{
struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
struct iommu_dma_cookie *cookie = domain->iova_cookie;
- struct iova_domain *iovad = &cookie->iovad;
- size_t iova_off = iova_offset(iovad, phys);
+ size_t iova_off = 0;
dma_addr_t iova;
- size = iova_align(iovad, size + iova_off);
+ if (cookie->type == IOMMU_DMA_IOVA_COOKIE) {
+ iova_off = iova_offset(&cookie->iovad, phys);
+ size = iova_align(&cookie->iovad, size + iova_off);
+ }
On 04/13/2017 06:21 AM, Robin Murphy wrote:
> Hi Nate,
>
> On 13/04/17 09:55, Nate Watterson wrote:
>> Currently, the __iommu_dma_{map/free} functions call iova_{offset/align}
>> making them unsuitable for use with iommu_domains having an IOMMU_DMA_MSI
>> cookie since the cookie's iova_domain member, iovad, is uninitialized.
>>
>> Now that iommu_dma_get_msi_page() calls __iommu_dma_map() regardless
>> of cookie type, failures are being seen when mapping MSI target
>> addresses for devices attached to UNMANAGED domains. To work around
>> this issue, the iova_domain granule for IOMMU_DMA_MSI cookies is
>> initialized to the value returned by cookie_msi_granule().
> Oh bum. Thanks for the report.
>
> However, I really don't like bodging around it with deliberate undefined
> behaviour. Fixing things properly doesn't seem too hard:
>
> ----->8-----
> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
> index 8348f366ddd1..62618e77bedc 100644
> --- a/drivers/iommu/dma-iommu.c
> +++ b/drivers/iommu/dma-iommu.c
> @@ -396,13 +396,13 @@ static void iommu_dma_free_iova(struct
> iommu_dma_cookie *cookie,
> dma_addr_t iova, size_t size)
> {
> struct iova_domain *iovad = &cookie->iovad;
> - unsigned long shift = iova_shift(iovad);
>
> /* The MSI case is only ever cleaning up its most recent
> allocation */
> if (cookie->type == IOMMU_DMA_MSI_COOKIE)
> cookie->msi_iova -= size;
> else
> - free_iova_fast(iovad, iova >> shift, size >> shift);
> + free_iova_fast(iovad, iova_pfn(iovad, iova),
> + size >> iova_shift(iovad));
> }
>
> static void __iommu_dma_unmap(struct iommu_domain *domain, dma_addr_t
> dma_addr,
> @@ -617,11 +617,14 @@ static dma_addr_t __iommu_dma_map(struct device
> *dev, phys_addr_t phys,
> {
> struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
> struct iommu_dma_cookie *cookie = domain->iova_cookie;
> - struct iova_domain *iovad = &cookie->iovad;
> - size_t iova_off = iova_offset(iovad, phys);
> + size_t iova_off = 0;
> dma_addr_t iova;
>
> - size = iova_align(iovad, size + iova_off);
> + if (cookie->type == IOMMU_DMA_IOVA_COOKIE) {
> + iova_off = iova_offset(&cookie->iovad, phys);
> + size = iova_align(&cookie->iovad, size + iova_off);
> + }
> +
> iova = iommu_dma_alloc_iova(domain, size, dma_get_mask(dev), dev);
> if (!iova)
> return DMA_ERROR_CODE;
> -----8<-----
>
> Untested, and you'll probably want to double-check it anyway given that
> the original oversight was mine in the first place ;)
>
> Robin.
>
>> Fixes: a44e6657585b ("iommu/dma: Clean up MSI IOVA allocation")
>> Signed-off-by: Nate Watterson <nwatters@...eaurora.org>
>> ---
>> drivers/iommu/dma-iommu.c | 10 ++++++++++
>> 1 file changed, 10 insertions(+)
>>
>> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
>> index 8348f366..d7b0816 100644
>> --- a/drivers/iommu/dma-iommu.c
>> +++ b/drivers/iommu/dma-iommu.c
>> @@ -127,6 +127,16 @@ int iommu_get_msi_cookie(struct iommu_domain *domain, dma_addr_t base)
>>
>> cookie->msi_iova = base;
>> domain->iova_cookie = cookie;
>> +
>> + /*
>> + * Setup granule for compatibility with __iommu_dma_{alloc/free} and
>> + * add a compile time check to ensure that writing granule won't
>> + * clobber msi_iova.
>> + */
>> + cookie->iovad.granule = cookie_msi_granule(cookie);
>> + BUILD_BUG_ON(offsetof(struct iova_domain, granule) <
>> + sizeof(cookie->msi_iova));
>> +
>> return 0;
>> }
>> EXPORT_SYMBOL(iommu_get_msi_cookie);
>>
--
Shanker Donthineni
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.
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