linux-kernel - Re: [PATCH v6 2/3] iommu/pci: reserve IOVA for PCI masters

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Message-ID: <20170517171154.GF31462@bhelgaas-glaptop.roam.corp.google.com>
Date:   Wed, 17 May 2017 12:11:54 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Oza Pawandeep <oza.oza@...adcom.com>
Cc:     Joerg Roedel <joro@...tes.org>,
        Robin Murphy <robin.murphy@....com>,
        iommu@...ts.linux-foundation.org, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        devicetree@...r.kernel.org, bcm-kernel-feedback-list@...adcom.com,
        Oza Pawandeep <oza.pawandeep@...il.com>
Subject: Re: [PATCH v6 2/3] iommu/pci: reserve IOVA for PCI masters

On Tue, May 16, 2017 at 10:52:06AM +0530, Oza Pawandeep wrote:
> this patch reserves the IOVA for PCI masters.
> ARM64 based SOCs may have scattered memory banks.
> such as iproc based SOC has
> 
> <0x00000000 0x80000000 0x0 0x80000000>, /* 2G @ 2G */
> <0x00000008 0x80000000 0x3 0x80000000>, /* 14G @ 34G */
> <0x00000090 0x00000000 0x4 0x00000000>, /* 16G @ 576G */
> <0x000000a0 0x00000000 0x4 0x00000000>; /* 16G @ 640G */
> 
> but incoming PCI transcation addressing capability is limited

s/transcation/transaction/

> by host bridge, for example if max incoming window capability
> is 512 GB, then 0x00000090 and 0x000000a0 will fall beyond it.
> 
> to address this problem, iommu has to avoid allocating IOVA which

s/iommu/IOMMU/

> are reserved. which inturn does not allocate IOVA if it falls into hole.

s/inturn/in turn/