From: Will Deacon <will.deacon@arm.com>
To: Anup Patel <anup.patel@broadcom.com>
Cc: Robin Murphy <robin.murphy@arm.com>,
Joerg Roedel <joro@8bytes.org>,
Baptiste Reynal <b.reynal@virtualopensystems.com>,
Alex Williamson <alex.williamson@redhat.com>,
Scott Branden <sbranden@broadcom.com>,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
iommu@lists.linux-foundation.org, kvm@vger.kernel.org,
bcm-kernel-feedback-list@broadcom.com
Subject: Re: [PATCH v2 1/2] vfio: Allow No-IOMMU mode without checking iommu_present()
Date: Thu, 20 Jul 2017 10:19:10 +0100 [thread overview]
Message-ID: <20170720091909.GC17837@arm.com> (raw)
In-Reply-To: <1500525154-5200-2-git-send-email-anup.patel@broadcom.com>
On Thu, Jul 20, 2017 at 10:02:33AM +0530, Anup Patel wrote:
> Not allowing No-IOMMU mode for devices already having
> iommu_ops on their bus is very conservative.
>
> We now have IOMMU (such as ARM SMMU) which can bypass
> transcations when IOMMU is not configured for a given
> device. In addition, it is not necessary to have all
> devices on bus to be upstream to an IOMMU on that bus.
How does the SMMU know to bypass in these cases? As I explained before, the
driver-specific command line option is the wrong way to go about arranging
this.
Will
WARNING: multiple messages have this Message-ID (diff)
From: will.deacon@arm.com (Will Deacon)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 1/2] vfio: Allow No-IOMMU mode without checking iommu_present()
Date: Thu, 20 Jul 2017 10:19:10 +0100 [thread overview]
Message-ID: <20170720091909.GC17837@arm.com> (raw)
In-Reply-To: <1500525154-5200-2-git-send-email-anup.patel@broadcom.com>
On Thu, Jul 20, 2017 at 10:02:33AM +0530, Anup Patel wrote:
> Not allowing No-IOMMU mode for devices already having
> iommu_ops on their bus is very conservative.
>
> We now have IOMMU (such as ARM SMMU) which can bypass
> transcations when IOMMU is not configured for a given
> device. In addition, it is not necessary to have all
> devices on bus to be upstream to an IOMMU on that bus.
How does the SMMU know to bypass in these cases? As I explained before, the
driver-specific command line option is the wrong way to go about arranging
this.
Will
next prev parent reply other threads:[~2017-07-20 9:19 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-20 4:32 [PATCH v2 0/2] FlexRM support in VFIO platform Anup Patel
2017-07-20 4:32 ` Anup Patel
[not found] ` <1500525154-5200-1-git-send-email-anup.patel-dY08KVG/lbpWk0Htik3J/w@public.gmane.org>
2017-07-20 4:32 ` [PATCH v2 1/2] vfio: Allow No-IOMMU mode without checking iommu_present() Anup Patel via iommu
2017-07-20 4:32 ` Anup Patel
2017-07-20 4:32 ` Anup Patel
2017-07-20 9:19 ` Will Deacon [this message]
2017-07-20 9:19 ` Will Deacon
[not found] ` <1500525154-5200-2-git-send-email-anup.patel-dY08KVG/lbpWk0Htik3J/w@public.gmane.org>
2017-07-24 17:24 ` Alex Williamson
2017-07-24 17:24 ` Alex Williamson
2017-07-24 17:24 ` Alex Williamson
2017-07-20 4:32 ` [PATCH v2 2/2] vfio: platform: reset: Add Broadcom FlexRM reset module Anup Patel via iommu
2017-07-20 4:32 ` Anup Patel
2017-07-20 4:32 ` Anup Patel
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