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From: Christoph Hellwig <hch@lst.de>
To: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Christoph Hellwig <hch@lst.de>, Halil Pasic <pasic@linux.ibm.com>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Jason Wang <jasowang@redhat.com>,
	Marek Szyprowski <m.szyprowski@samsung.com>,
	Robin Murphy <robin.murphy@arm.com>,
	linux-s390@vger.kernel.org,
	virtualization@lists.linux-foundation.org,
	linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
	Janosch Frank <frankja@linux.ibm.com>,
	Viktor Mihajlovski <mihajlov@linux.ibm.com>,
	Cornelia Huck <cohuck@redhat.com>, Ram Pai <linuxram@us.ibm.com>,
	Thiago Jung Bauermann <bauerman@linux.ibm.com>,
	David Gibson <david@gibson.dropbear.id.au>,
	"Lendacky, Thomas" <Thomas.Lendacky@amd.com>,
	Michael Mueller <mimu@linux.ibm.com>
Subject: Re: [PATCH 1/2] mm: move force_dma_unencrypted() to mem_encrypt.h
Date: Thu, 20 Feb 2020 17:31:35 +0100	[thread overview]
Message-ID: <20200220163135.GA13192@lst.de> (raw)
In-Reply-To: <4369f099-e4e4-4a58-b38b-642cf53ccca6@de.ibm.com>

On Thu, Feb 20, 2020 at 05:23:20PM +0100, Christian Borntraeger wrote:
> >From a users perspective it makes absolutely perfect sense to use the
> bounce buffers when they are NEEDED. 
> Forcing the user to specify iommu_platform just because you need bounce buffers
> really feels wrong. And obviously we have a severe performance issue
> because of the indirections.

The point is that the user should not have to specify iommu_platform.
We need to make sure any new hypervisor (especially one that might require
bounce buffering) always sets it, as was a rather bogus legacy hack
that isn't extensibe for cases that for example require bounce buffering.

WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: linux-s390@vger.kernel.org, Janosch Frank <frankja@linux.ibm.com>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Jason Wang <jasowang@redhat.com>,
	Cornelia Huck <cohuck@redhat.com>, Ram Pai <linuxram@us.ibm.com>,
	linux-kernel@vger.kernel.org,
	virtualization@lists.linux-foundation.org,
	Halil Pasic <pasic@linux.ibm.com>,
	iommu@lists.linux-foundation.org,
	David Gibson <david@gibson.dropbear.id.au>,
	Michael Mueller <mimu@linux.ibm.com>,
	"Lendacky, Thomas" <Thomas.Lendacky@amd.com>,
	Viktor Mihajlovski <mihajlov@linux.ibm.com>,
	Robin Murphy <robin.murphy@arm.com>,
	Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH 1/2] mm: move force_dma_unencrypted() to mem_encrypt.h
Date: Thu, 20 Feb 2020 17:31:35 +0100	[thread overview]
Message-ID: <20200220163135.GA13192@lst.de> (raw)
In-Reply-To: <4369f099-e4e4-4a58-b38b-642cf53ccca6@de.ibm.com>

On Thu, Feb 20, 2020 at 05:23:20PM +0100, Christian Borntraeger wrote:
> >From a users perspective it makes absolutely perfect sense to use the
> bounce buffers when they are NEEDED. 
> Forcing the user to specify iommu_platform just because you need bounce buffers
> really feels wrong. And obviously we have a severe performance issue
> because of the indirections.

The point is that the user should not have to specify iommu_platform.
We need to make sure any new hypervisor (especially one that might require
bounce buffering) always sets it, as was a rather bogus legacy hack
that isn't extensibe for cases that for example require bounce buffering.
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu

WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: linux-s390@vger.kernel.org, Janosch Frank <frankja@linux.ibm.com>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Cornelia Huck <cohuck@redhat.com>, Ram Pai <linuxram@us.ibm.com>,
	linux-kernel@vger.kernel.org,
	virtualization@lists.linux-foundation.org,
	Halil Pasic <pasic@linux.ibm.com>,
	iommu@lists.linux-foundation.org,
	David Gibson <david@gibson.dropbear.id.au>,
	Michael Mueller <mimu@linux.ibm.com>,
	"Lendacky, Thomas" <Thomas.Lendacky@amd.com>,
	Viktor Mihajlovski <mihajlov@linux.ibm.com>,
	Robin Murphy <robin.murphy@arm.com>,
	Christoph Hellwig <hch@lst.de>,
	Marek Szyprowski <m.szyprowski@samsung.com>
Subject: Re: [PATCH 1/2] mm: move force_dma_unencrypted() to mem_encrypt.h
Date: Thu, 20 Feb 2020 17:31:35 +0100	[thread overview]
Message-ID: <20200220163135.GA13192@lst.de> (raw)
In-Reply-To: <4369f099-e4e4-4a58-b38b-642cf53ccca6@de.ibm.com>

On Thu, Feb 20, 2020 at 05:23:20PM +0100, Christian Borntraeger wrote:
> >From a users perspective it makes absolutely perfect sense to use the
> bounce buffers when they are NEEDED. 
> Forcing the user to specify iommu_platform just because you need bounce buffers
> really feels wrong. And obviously we have a severe performance issue
> because of the indirections.

The point is that the user should not have to specify iommu_platform.
We need to make sure any new hypervisor (especially one that might require
bounce buffering) always sets it, as was a rather bogus legacy hack
that isn't extensibe for cases that for example require bounce buffering.

  reply	other threads:[~2020-02-20 16:32 UTC|newest]

Thread overview: 124+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-20 16:06 [PATCH 0/2] virtio: decouple protected guest RAM form VIRTIO_F_IOMMU_PLATFORM Halil Pasic
2020-02-20 16:06 ` Halil Pasic
2020-02-20 16:06 ` [PATCH 1/2] mm: move force_dma_unencrypted() to mem_encrypt.h Halil Pasic
2020-02-20 16:06   ` Halil Pasic
2020-02-20 16:11   ` Christoph Hellwig
2020-02-20 16:11     ` Christoph Hellwig
2020-02-20 16:23     ` Christian Borntraeger
2020-02-20 16:23       ` Christian Borntraeger
2020-02-20 16:31       ` Christoph Hellwig [this message]
2020-02-20 16:31         ` Christoph Hellwig
2020-02-20 16:31         ` Christoph Hellwig
2020-02-20 17:00         ` Christian Borntraeger
2020-02-20 17:00           ` Christian Borntraeger
2020-02-21  3:27         ` David Gibson
2020-02-21  3:27           ` David Gibson
2020-02-21 13:06           ` Halil Pasic
2020-02-21 13:06             ` Halil Pasic
2020-02-21 15:48             ` Michael S. Tsirkin
2020-02-21 15:48               ` Michael S. Tsirkin
2020-02-21 18:07               ` Halil Pasic
2020-02-21 18:07                 ` Halil Pasic
2020-02-24  3:33                 ` David Gibson
2020-02-24  3:33                   ` David Gibson
2020-02-24 18:49                   ` Halil Pasic
2020-02-24 18:49                     ` Halil Pasic
2020-02-25 18:08                     ` Cornelia Huck
2020-02-25 18:08                       ` Cornelia Huck
2020-02-28  0:23                       ` David Gibson
2020-02-28  0:23                         ` David Gibson
2020-02-20 16:06 ` [PATCH 2/2] virtio: let virtio use DMA API when guest RAM is protected Halil Pasic
2020-02-20 16:06   ` Halil Pasic
2020-02-20 16:13   ` Christoph Hellwig
2020-02-20 16:13     ` Christoph Hellwig
2020-02-21  2:59     ` David Gibson
2020-02-21  2:59       ` David Gibson
2020-02-21  3:41       ` Jason Wang
2020-02-21  3:41         ` Jason Wang
2020-02-21 13:31         ` Halil Pasic
2020-02-21 13:31           ` Halil Pasic
2020-02-21 13:27       ` Halil Pasic
2020-02-21 13:27         ` Halil Pasic
2020-02-21 16:36       ` Christoph Hellwig
2020-02-21 16:36         ` Christoph Hellwig
2020-02-24  6:50         ` David Gibson
2020-02-24  6:50           ` David Gibson
2020-02-24 18:59         ` Halil Pasic
2020-02-24 18:59           ` Halil Pasic
2020-02-24 18:59           ` Halil Pasic
2020-02-21 14:33     ` Halil Pasic
2020-02-21 14:33       ` Halil Pasic
2020-02-21 16:39       ` Christoph Hellwig
2020-02-21 16:39         ` Christoph Hellwig
2020-02-21 18:16         ` Halil Pasic
2020-02-21 18:16           ` Halil Pasic
2020-02-21 18:16           ` Halil Pasic
2020-02-22 19:07       ` Michael S. Tsirkin
2020-02-22 19:07         ` Michael S. Tsirkin
2020-02-24 17:16         ` Christoph Hellwig
2020-02-24 17:16           ` Christoph Hellwig
2020-10-28 14:24           ` Alexander Graf via iommu
2020-10-28 18:01             ` Michael S. Tsirkin
2020-10-28 18:01               ` Michael S. Tsirkin
2020-10-28 18:01               ` Michael S. Tsirkin
2020-02-20 20:55   ` Michael S. Tsirkin
2020-02-20 20:55     ` Michael S. Tsirkin
2020-02-21  1:17     ` Ram Pai
2020-02-21  1:17       ` Ram Pai
2020-02-21  1:17       ` Ram Pai
2020-02-21  3:29       ` David Gibson
2020-02-21  3:29         ` David Gibson
2020-02-21 13:12     ` Halil Pasic
2020-02-21 13:12       ` Halil Pasic
2020-02-21 15:39       ` Tom Lendacky
2020-02-21 15:39         ` Tom Lendacky
2020-02-24  6:40         ` David Gibson
2020-02-24  6:40           ` David Gibson
2020-02-24  6:40           ` David Gibson
2020-02-21 15:56       ` Michael S. Tsirkin
2020-02-21 15:56         ` Michael S. Tsirkin
2020-02-21 16:35         ` Christoph Hellwig
2020-02-21 16:35           ` Christoph Hellwig
2020-02-21 18:03         ` Halil Pasic
2020-02-21 18:03           ` Halil Pasic
2020-02-20 20:48 ` [PATCH 0/2] virtio: decouple protected guest RAM form VIRTIO_F_IOMMU_PLATFORM Michael S. Tsirkin
2020-02-20 20:48   ` Michael S. Tsirkin
2020-02-20 21:29 ` Michael S. Tsirkin
2020-02-20 21:29   ` Michael S. Tsirkin
2020-02-21 13:37   ` Halil Pasic
2020-02-21 13:37     ` Halil Pasic
2020-02-20 21:33 ` Michael S. Tsirkin
2020-02-20 21:33   ` Michael S. Tsirkin
2020-02-21 13:49   ` Halil Pasic
2020-02-21 13:49     ` Halil Pasic
2020-02-21 16:41   ` Christoph Hellwig
2020-02-21 16:41     ` Christoph Hellwig
2020-02-24  5:44     ` David Gibson
2020-02-24  5:44       ` David Gibson
2020-02-24  5:44       ` David Gibson
2020-02-21  6:22 ` Jason Wang
2020-02-21  6:22   ` Jason Wang
2020-02-21 14:56   ` Halil Pasic
2020-02-21 14:56     ` Halil Pasic
2020-02-24  3:38     ` David Gibson
2020-02-24  3:38       ` David Gibson
2020-02-24  4:01     ` Jason Wang
2020-02-24  4:01       ` Jason Wang
2020-02-24  4:01       ` Jason Wang
2020-02-24  6:06       ` Michael S. Tsirkin
2020-02-24  6:06         ` Michael S. Tsirkin
2020-02-24  6:45         ` Jason Wang
2020-02-24  6:45           ` Jason Wang
2020-02-24  7:48           ` Michael S. Tsirkin
2020-02-24  7:48             ` Michael S. Tsirkin
2020-02-24  9:26             ` Jason Wang
2020-02-24  9:26               ` Jason Wang
2020-02-24 13:40               ` Michael S. Tsirkin
2020-02-24 13:40                 ` Michael S. Tsirkin
2020-02-25  3:38                 ` Jason Wang
2020-02-25  3:38                   ` Jason Wang
2020-02-24 13:56               ` Halil Pasic
2020-02-24 13:56                 ` Halil Pasic
2020-02-25  3:30                 ` Jason Wang
2020-02-25  3:30                   ` Jason Wang
2020-02-25  3:30                   ` Jason Wang

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