IOMMU Archive on lore.kernel.org
 help / color / Atom feed
From: "Lendacky, Thomas" <Thomas.Lendacky@amd.com>
To: Christoph Hellwig <hch@lst.de>, Halil Pasic <pasic@linux.ibm.com>
Cc: "linux-s390@vger.kernel.org" <linux-s390@vger.kernel.org>,
	Mike Anderson <andmike@linux.ibm.com>,
	Janosch Frank <frankja@linux.ibm.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	Robin Murphy <robin.murphy@arm.com>,
	"x86@kernel.org" <x86@kernel.org>, Ram Pai <linuxram@us.ibm.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"iommu@lists.linux-foundation.org"
	<iommu@lists.linux-foundation.org>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	"H. Peter Anvin" <hpa@zytor.com>,
	"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
	Alexey Dobriyan <adobriyan@gmail.com>
Subject: Re: [PATCH 3/3] fs/core/vmcore: Move sev_active() reference to x86 arch code
Date: Mon, 15 Jul 2019 15:44:45 +0000
Message-ID: <56b79040-257b-3a89-c9d2-5842594cad17@amd.com> (raw)
In-Reply-To: <20190715143039.GA6892@lst.de>

On 7/15/19 9:30 AM, Christoph Hellwig wrote:
> On Mon, Jul 15, 2019 at 04:03:17PM +0200, Halil Pasic wrote:
>>> I thought about that but couldn't put my finger on a general concept.
>>> Is it "guest with memory inaccessible to the host"?
>>>
>>
>> Well, force_dma_unencrypted() is a much better name thatn sev_active():
>> s390 has no AMD SEV, that is sure, but for virtio to work we do need to
>> make our dma accessible to the hypervisor. Yes, your "guest with memory
>> inaccessible to the host" shows into the right direction IMHO.
>> Unfortunately I don't have too many cycles to spend on this right now.
> 
> In x86 it means that we need to remove dma encryption using
> set_memory_decrypted before using it for DMA purposes.  In the SEV
> case that seems to be so that the hypervisor can access it, in the SME
> case that Tom just fixes it is because there is an encrypted bit set
> in the physical address, and if the device doesn't support a large
> enough DMA address the direct mapping code has to encrypt the pages
> used for the contigous allocation.

Just a correction/clarification...

For SME, when a device doesn't support a large enough DMA address to
accommodate the encryption bit as part of the DMA address, the direct
mapping code has to provide un-encrypted pages. For un-encrypted pages,
the DMA address now does not include the encryption bit, making it
acceptable to the device. Since the device is now using a DMA address
without the encryption bit, the physical address in the CPU page table
must match (the call to set_memory_decrypted) so that both the device and
the CPU interact in the same way with the memory.

Thanks,
Tom

> 
>> Being on cc for your patch made me realize that things got broken on
>> s390. Thanks! I've sent out a patch that fixes protvirt, but we are going
>> to benefit from your cleanups. I think with your cleanups and that patch
>> of mine both sev_active() and sme_active() can be removed. Feel free to
>> do so. If not, I can attend to it as well.
> 
> Yes, I think with the dma-mapping fix and this series sme_active and
> sev_active should be gone from common code.  We should also be able
> to remove the exports x86 has for them.
> 
> I'll wait a few days and will then feed the dma-mapping fix to Linus,
> it might make sense to either rebase Thiagos series on top of the
> dma-mapping for-next branch, or wait a few days before reposting.
> 
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu

  reply index

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-12  5:36 [PATCH 0/3] Remove x86-specific code from generic headers Thiago Jung Bauermann
2019-07-12  5:36 ` [PATCH 1/3] x86/Kconfig: Move ARCH_HAS_MEM_ENCRYPT to arch/Kconfig Thiago Jung Bauermann
2019-07-12 16:04   ` Thomas Gleixner
2019-07-12 23:35     ` Thiago Jung Bauermann
2019-07-12  5:36 ` [PATCH 2/3] DMA mapping: Move SME handling to x86-specific files Thiago Jung Bauermann
2019-07-12  7:13   ` Christoph Hellwig
2019-07-12 23:42     ` Thiago Jung Bauermann
2019-07-12 16:09   ` Thomas Gleixner
2019-07-18 19:47     ` Thiago Jung Bauermann
2019-07-19  9:05   ` kbuild test robot
2019-07-20  0:22     ` Thiago Jung Bauermann
2019-07-12  5:36 ` [PATCH 3/3] fs/core/vmcore: Move sev_active() reference to x86 arch code Thiago Jung Bauermann
2019-07-12 13:09   ` Halil Pasic
2019-07-12 14:08     ` Christoph Hellwig
2019-07-12 14:51       ` Halil Pasic
2019-07-12 15:11         ` Christoph Hellwig
2019-07-12 15:42           ` Halil Pasic
2019-07-13  8:08             ` Christoph Hellwig
2019-07-12 21:55     ` Thiago Jung Bauermann
2019-07-15 14:03       ` Halil Pasic
2019-07-15 14:30         ` Christoph Hellwig
2019-07-15 15:44           ` Lendacky, Thomas [this message]
2019-07-15 20:14           ` Thiago Jung Bauermann
2019-07-13  4:45 [PATCH 0/3] Remove x86-specific code from generic headers Thiago Jung Bauermann
2019-07-13  4:45 ` [PATCH 3/3] fs/core/vmcore: Move sev_active() reference to x86 arch code Thiago Jung Bauermann

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=56b79040-257b-3a89-c9d2-5842594cad17@amd.com \
    --to=thomas.lendacky@amd.com \
    --cc=adobriyan@gmail.com \
    --cc=andmike@linux.ibm.com \
    --cc=bp@alien8.de \
    --cc=frankja@linux.ibm.com \
    --cc=hch@lst.de \
    --cc=hpa@zytor.com \
    --cc=iommu@lists.linux-foundation.org \
    --cc=konrad.wilk@oracle.com \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-s390@vger.kernel.org \
    --cc=linuxppc-dev@lists.ozlabs.org \
    --cc=linuxram@us.ibm.com \
    --cc=mingo@redhat.com \
    --cc=pasic@linux.ibm.com \
    --cc=robin.murphy@arm.com \
    --cc=tglx@linutronix.de \
    --cc=x86@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

IOMMU Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-iommu/0 linux-iommu/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-iommu linux-iommu/ https://lore.kernel.org/linux-iommu \
		iommu@lists.linux-foundation.org iommu@archiver.kernel.org
	public-inbox-index linux-iommu

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.linux-foundation.lists.iommu


AGPL code for this site: git clone https://public-inbox.org/ public-inbox