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From: "Thomas Hellström (VMware)" <thomas_os@shipmail.org>
To: Daniel Vetter <daniel@ffwll.ch>
Cc: "Andy Lutomirski" <luto@amacapital.net>,
	"Andy Lutomirski" <luto@kernel.org>,
	"Dave Hansen" <dave.hansen@intel.com>,
	dri-devel <dri-devel@lists.freedesktop.org>,
	pv-drivers@vmware.com,
	"VMware Graphics" <linux-graphics-maintainer@vmware.com>,
	"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
	"Tom Lendacky" <thomas.lendacky@amd.com>,
	"Thomas Hellstrom" <thellstrom@vmware.com>,
	"Peter Zijlstra" <peterz@infradead.org>,
	"Dave Hansen" <dave.hansen@linux.intel.com>,
	"Heiko Carstens" <heiko.carstens@de.ibm.com>,
	"Christian Borntraeger" <borntraeger@de.ibm.com>,
	"Ingo Molnar" <mingo@redhat.com>,
	"Borislav Petkov" <bp@alien8.de>,
	"H. Peter Anvin" <hpa@zytor.com>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Christian König" <christian.koenig@amd.com>
Subject: Re: [PATCH v2 3/4] drm/ttm, drm/vmwgfx: Correctly support support AMD memory encryption
Date: Wed, 4 Sep 2019 12:37:45 +0200	[thread overview]
Message-ID: <0fd10438-5da4-fb69-f40c-c9b4beea1977@shipmail.org> (raw)
In-Reply-To: <CAKMK7uH0jxaWJLxfXfGLyN-Rb=0ZKUFTkrEPdFCuGCh4ORCv9w@mail.gmail.com>

On 9/4/19 9:53 AM, Daniel Vetter wrote:
> On Wed, Sep 4, 2019 at 8:49 AM Thomas Hellström (VMware)
> <thomas_os@shipmail.org> wrote:
>> On 9/4/19 1:15 AM, Andy Lutomirski wrote:
>>> But, reading this, I have more questions:
>>>
>>> Can’t you get rid of cvma by using vmf_insert_pfn_prot()?
>> It looks like that, although there are comments in the code about
>> serious performance problems using VM_PFNMAP / vmf_insert_pfn() with
>> write-combining and PAT, so that would require some serious testing with
>> hardware I don't have. But I guess there is definitely room for
>> improvement here. Ideally we'd like to be able to change the
>> vma->vm_page_prot within fault(). But we can
> Just a quick comment on this: It's the repeated (per-pfn/pte) lookup
> of the PAT tables, which are dead slow. If you have a struct
> io_mapping then that can be done once, and then just blindly inserted.
> See remap_io_mapping in i915.
> -Daniel

Thanks, Daniel.

Indeed looks a lot like remap_pfn_range(), but usable at fault time?

/Thomas



WARNING: multiple messages have this Message-ID (diff)
From: "Thomas Hellström (VMware)" <thomas_os@shipmail.org>
To: Daniel Vetter <daniel@ffwll.ch>
Cc: "Tom Lendacky" <thomas.lendacky@amd.com>,
	"Thomas Hellstrom" <thellstrom@vmware.com>,
	"Christian Borntraeger" <borntraeger@de.ibm.com>,
	pv-drivers@vmware.com,
	"Dave Hansen" <dave.hansen@linux.intel.com>,
	"Heiko Carstens" <heiko.carstens@de.ibm.com>,
	"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
	dri-devel <dri-devel@lists.freedesktop.org>,
	"Andy Lutomirski" <luto@amacapital.net>,
	"Dave Hansen" <dave.hansen@intel.com>,
	"Peter Zijlstra" <peterz@infradead.org>,
	"Ingo Molnar" <mingo@redhat.com>,
	"VMware Graphics" <linux-graphics-maintainer@vmware.com>,
	"Andy Lutomirski" <luto@kernel.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	"Borislav Petkov" <bp@alien8.de>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Christian König" <christian.koenig@amd.com>
Subject: Re: [PATCH v2 3/4] drm/ttm, drm/vmwgfx: Correctly support support AMD memory encryption
Date: Wed, 4 Sep 2019 12:37:45 +0200	[thread overview]
Message-ID: <0fd10438-5da4-fb69-f40c-c9b4beea1977@shipmail.org> (raw)
In-Reply-To: <CAKMK7uH0jxaWJLxfXfGLyN-Rb=0ZKUFTkrEPdFCuGCh4ORCv9w@mail.gmail.com>

On 9/4/19 9:53 AM, Daniel Vetter wrote:
> On Wed, Sep 4, 2019 at 8:49 AM Thomas Hellström (VMware)
> <thomas_os@shipmail.org> wrote:
>> On 9/4/19 1:15 AM, Andy Lutomirski wrote:
>>> But, reading this, I have more questions:
>>>
>>> Can’t you get rid of cvma by using vmf_insert_pfn_prot()?
>> It looks like that, although there are comments in the code about
>> serious performance problems using VM_PFNMAP / vmf_insert_pfn() with
>> write-combining and PAT, so that would require some serious testing with
>> hardware I don't have. But I guess there is definitely room for
>> improvement here. Ideally we'd like to be able to change the
>> vma->vm_page_prot within fault(). But we can
> Just a quick comment on this: It's the repeated (per-pfn/pte) lookup
> of the PAT tables, which are dead slow. If you have a struct
> io_mapping then that can be done once, and then just blindly inserted.
> See remap_io_mapping in i915.
> -Daniel

Thanks, Daniel.

Indeed looks a lot like remap_pfn_range(), but usable at fault time?

/Thomas


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  reply	other threads:[~2019-09-04 10:38 UTC|newest]

Thread overview: 53+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-03 13:15 [PATCH v2 0/4] Have TTM support SEV encryption with coherent memory Thomas Hellström (VMware)
2019-09-03 13:15 ` [PATCH v2 1/4] x86/mm: Export force_dma_unencrypted Thomas Hellström (VMware)
2019-09-03 13:46   ` Christoph Hellwig
2019-09-03 14:32     ` Thomas Hellström (VMware)
2019-09-03 16:22       ` Christoph Hellwig
2019-09-03 16:22         ` Christoph Hellwig
2019-09-03 20:46         ` Thomas Hellström (VMware)
2019-09-03 20:46           ` Thomas Hellström (VMware)
2019-09-03 21:41           ` Andy Lutomirski
2019-09-04  6:58           ` Christoph Hellwig
2019-09-04  7:32             ` Thomas Hellström (VMware)
2019-09-04 12:22               ` Christoph Hellwig
2019-09-04 17:28                 ` Thomas Hellström (VMware)
2019-09-03 15:14   ` Dave Hansen
2019-09-03 15:14     ` Dave Hansen
2019-09-03 18:50     ` Thomas Hellström (VMware)
2019-09-03 18:50       ` Thomas Hellström (VMware)
2019-09-03 13:15 ` [PATCH v2 2/4] s390/mm: " Thomas Hellström (VMware)
2019-09-03 13:46   ` Christoph Hellwig
2019-09-03 13:15 ` [PATCH v2 3/4] drm/ttm, drm/vmwgfx: Correctly support support AMD memory encryption Thomas Hellström (VMware)
2019-09-03 19:38   ` Dave Hansen
2019-09-03 19:51     ` Daniel Vetter
2019-09-03 19:51       ` Daniel Vetter
2019-09-03 19:55       ` Dave Hansen
2019-09-03 20:36         ` Thomas Hellström (VMware)
2019-09-03 20:51           ` Dave Hansen
2019-09-03 21:05             ` Thomas Hellström (VMware)
2019-09-03 21:46               ` Andy Lutomirski
2019-09-03 22:08                 ` Thomas Hellström (VMware)
2019-09-03 22:15                   ` Thomas Hellström (VMware)
2019-09-03 22:15                     ` Thomas Hellström (VMware)
2019-09-03 23:10                     ` Dave Hansen
2019-09-04  8:34                       ` Thomas Hellström (VMware)
2019-09-03 23:15                     ` Andy Lutomirski
2019-09-04  6:49                       ` Thomas Hellström (VMware)
2019-09-04  7:53                         ` Daniel Vetter
2019-09-04 10:37                           ` Thomas Hellström (VMware) [this message]
2019-09-04 10:37                             ` Thomas Hellström (VMware)
2019-09-04 11:43                             ` Daniel Vetter
2019-09-04 18:16                         ` Christoph Hellwig
2019-09-04 18:16                           ` Christoph Hellwig
2019-09-04  7:33               ` Koenig, Christian
2019-09-04  8:19                 ` Thomas Hellström (VMware)
2019-09-04  8:42                   ` Thomas Hellström (VMware)
2019-09-04  8:42                     ` Thomas Hellström (VMware)
2019-09-04 11:10                   ` Koenig, Christian
2019-09-04 11:10                     ` Koenig, Christian
2019-09-04 12:35                     ` Thomas Hellström (VMware)
2019-09-04 12:35                       ` Thomas Hellström (VMware)
2019-09-04 13:05                       ` Thomas Hellström (VMware)
2019-09-03 13:15 ` [PATCH v2 4/4] drm/ttm: Cache dma pool decrypted pages when AMD SEV is active Thomas Hellström (VMware)
2019-09-03 15:18 ` [PATCH v2 0/4] Have TTM support SEV encryption with coherent memory Daniel Vetter
2019-09-05 10:43 ` Thomas Hellström (VMware)

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