From: "Lendacky, Thomas" <Thomas.Lendacky@amd.com>
To: Christoph Hellwig <hch@lst.de>, Halil Pasic <pasic@linux.ibm.com>
Cc: Thiago Jung Bauermann <bauerman@linux.ibm.com>,
Janosch Frank <frankja@linux.ibm.com>,
"x86@kernel.org" <x86@kernel.org>,
"iommu@lists.linux-foundation.org"
<iommu@lists.linux-foundation.org>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
"linux-s390@vger.kernel.org" <linux-s390@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"H. Peter Anvin" <hpa@zytor.com>,
Marek Szyprowski <m.szyprowski@samsung.com>,
Robin Murphy <robin.murphy@arm.com>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
Alexey Dobriyan <adobriyan@gmail.com>,
Mike Anderson <andmike@linux.ibm.com>,
Ram Pai <linuxram@us.ibm.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 [thread overview]
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.
>
next prev parent reply other threads:[~2019-07-15 15:45 UTC|newest]
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
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