From: Auger Eric <eric.auger@redhat.com>
To: Will Deacon <will@kernel.org>,
Vennila Megavannan <vemegava@linux.microsoft.com>
Cc: jean-philippe@linaro.org, linux-kernel@vger.kernel.org,
iommu@lists.linux-foundation.org, tyhicks@linux.microsoft.com,
srinath.mannam@broadcom.com,
bcm-kernel-feedback-list@broadcom.com, robin.murphy@arm.com,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2] iommu/arm: Add module parameter to set msi iova address
Date: Wed, 23 Sep 2020 08:32:43 +0200 [thread overview]
Message-ID: <85f7d1ae-71a9-4e95-8a30-03cc699d4794@redhat.com> (raw)
In-Reply-To: <20200921204545.GA3811@willie-the-truck>
Hi Will,
On 9/21/20 10:45 PM, Will Deacon wrote:
> On Mon, Sep 14, 2020 at 11:13:07AM -0700, Vennila Megavannan wrote:
>> From: Srinath Mannam <srinath.mannam@broadcom.com>
>>
>> Add provision to change default value of MSI IOVA base to platform's
>> suitable IOVA using module parameter. The present hardcoded MSI IOVA base
>> may not be the accessible IOVA ranges of platform.
>>
>> If any platform has the limitaion to access default MSI IOVA, then it can
>> be changed using "arm-smmu.msi_iova_base=0xa0000000" command line argument.
>>
>> Signed-off-by: Srinath Mannam <srinath.mannam@broadcom.com>
>> Co-developed-by: Vennila Megavannan <vemegava@linux.microsoft.com>
>> Signed-off-by: Vennila Megavannan <vemegava@linux.microsoft.com>
>> ---
>> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 5 ++++-
>> drivers/iommu/arm/arm-smmu/arm-smmu.c | 5 ++++-
>> 2 files changed, 8 insertions(+), 2 deletions(-)
>
> This feels pretty fragile. Wouldn't it be better to realise that there's
> a region conflict with iommu_dma_get_resv_regions() and move the MSI window
> accordingly at runtime?
Since cd2c9fcf5c66 ("iommu/dma: Move PCI window region reservation back
into dma specific path"), the PCI host bridge windows are not exposed by
iommu_dma_get_resv_regions() anymore. If I understood correctly, what is
attempted here is to avoid the collision between such PCI host bridge
window and the MSI IOVA range.
Thanks
Eric
>
> Will
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>
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next prev parent reply other threads:[~2020-09-23 6:32 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-14 18:13 [PATCH v2] iommu/arm: Add module parameter to set msi iova address Vennila Megavannan
2020-09-21 20:45 ` Will Deacon
2020-09-22 22:37 ` Vennila Megavannan
2020-09-23 6:32 ` Auger Eric [this message]
2020-09-28 20:56 ` Will Deacon
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