From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
To: Dave Hansen <dave.hansen@intel.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>,
Kai Huang <kai.huang@intel.com>,
Sathyanarayanan Kuppuswamy
<sathyanarayanan.kuppuswamy@linux.intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, "H . Peter Anvin" <hpa@zytor.com>,
Tony Luck <tony.luck@intel.com>, Andi Kleen <ak@linux.intel.com>,
Wander Lairson Costa <wander@redhat.com>,
Isaku Yamahata <isaku.yamahata@gmail.com>,
marcelo.cerri@canonical.com, tim.gardner@canonical.com,
khalid.elmously@canonical.com, philip.cox@canonical.com,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 3/3] x86/tdx: Add Quote generation support
Date: Mon, 9 May 2022 18:35:34 +0300 [thread overview]
Message-ID: <20220509153534.i6v4xcb2g24ia2i4@black.fi.intel.com> (raw)
In-Reply-To: <4506e2c2-af4b-623d-5618-48269e65c295@intel.com>
On Mon, May 09, 2022 at 07:14:20AM -0700, Dave Hansen wrote:
> On 5/9/22 05:09, Kirill A. Shutemov wrote:
> > Private->Shared conversion is destructive. You have to split SEPT, flush
> > TLB. Backward conversion even more costly.
> >
> > Rule of thumb is avoid conversion where possible. DMA API is there for
> > you.
>
> Kirill, I understand that the DMA API is a quick fix today. But is it
> _really_ the right long-term interface?
Yes, I think so.
> There will surely come a time when TDX I/O devices won't be using fixed
> bounce buffers. What will the quote generation code do then? How will
> we know to come back around and fix this up?
VirtIO will not go away with TDX I/O in picture. TDX I/O will be addition
to existing stuff, not replacement.
And we have hooks in place to accommodate this: force_dma_unencrypted()
will return false for devices capable of TDX I/O. While the rest of
devices, including VirtIO and attestation, keep using existing paths with
swiotlb.
> Does SEV or the s390 ultravisor need anything like this?
At quick glance sev-guest.c uses set_memory_decrypted()/encrypted() for
allocation and freeing shared memory. I consider it inferior to using DMA
API.
--
Kirill A. Shutemov
next prev parent reply other threads:[~2022-05-09 15:35 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-01 18:34 [PATCH v5 0/3] Add TDX Guest Attestation support Kuppuswamy Sathyanarayanan
2022-05-01 18:34 ` [PATCH v5 1/3] x86/tdx: Add TDX Guest attestation interface driver Kuppuswamy Sathyanarayanan
2022-05-02 2:31 ` Kai Huang
2022-05-02 15:52 ` Sathyanarayanan Kuppuswamy
2022-05-02 22:30 ` Kai Huang
2022-05-02 23:17 ` Sathyanarayanan Kuppuswamy
2022-05-02 23:37 ` Kai Huang
2022-05-03 14:38 ` Wander Costa
2022-05-03 15:09 ` Sathyanarayanan Kuppuswamy
2022-05-03 22:08 ` Kai Huang
2022-05-02 12:18 ` Wander Lairson Costa
2022-05-02 16:06 ` Sathyanarayanan Kuppuswamy
2022-05-01 18:34 ` [PATCH v5 2/3] x86/tdx: Add TDX Guest event notify interrupt support Kuppuswamy Sathyanarayanan
2022-05-02 12:44 ` Wander Lairson Costa
2022-05-01 18:35 ` [PATCH v5 3/3] x86/tdx: Add Quote generation support Kuppuswamy Sathyanarayanan
2022-05-02 2:40 ` Kai Huang
2022-05-03 1:27 ` Kirill A. Shutemov
2022-05-03 2:18 ` Kai Huang
2022-05-03 2:39 ` Sathyanarayanan Kuppuswamy
2022-05-03 22:13 ` Kai Huang
2022-05-03 2:45 ` Kirill A. Shutemov
2022-05-03 3:36 ` Kai Huang
2022-05-03 22:24 ` Dave Hansen
2022-05-03 22:28 ` Sathyanarayanan Kuppuswamy
2022-05-03 22:30 ` Sathyanarayanan Kuppuswamy
2022-05-04 22:49 ` Sathyanarayanan Kuppuswamy
2022-05-04 23:28 ` Kai Huang
2022-05-05 20:53 ` Sathyanarayanan Kuppuswamy
2022-05-05 22:15 ` Kai Huang
2022-05-05 22:38 ` Sathyanarayanan Kuppuswamy
2022-05-05 23:06 ` Dave Hansen
2022-05-06 0:11 ` Kai Huang
2022-05-06 1:55 ` Sathyanarayanan Kuppuswamy
2022-05-07 0:42 ` Kirill A. Shutemov
2022-05-09 3:37 ` Kai Huang
2022-05-09 12:09 ` Kirill A. Shutemov
2022-05-09 14:14 ` Dave Hansen
2022-05-09 15:35 ` Kirill A. Shutemov [this message]
2022-05-09 15:43 ` Sathyanarayanan Kuppuswamy
2022-05-09 23:54 ` Kai Huang
2022-05-10 0:17 ` Sathyanarayanan Kuppuswamy
2022-05-10 1:30 ` Kirill A. Shutemov
2022-05-10 1:40 ` Kai Huang
2022-05-10 10:42 ` Kai Huang
2022-05-16 17:39 ` Sathyanarayanan Kuppuswamy
2022-05-06 11:00 ` Kai Huang
2022-05-06 15:47 ` Dave Hansen
2022-05-07 1:00 ` Kirill A. Shutemov
2022-05-05 10:50 ` Kai Huang
2022-05-05 19:03 ` Sathyanarayanan Kuppuswamy
2022-05-05 22:25 ` Kai Huang
2022-05-02 5:01 ` Kai Huang
2022-05-02 16:02 ` Sathyanarayanan Kuppuswamy
2022-05-02 23:02 ` Kai Huang
2022-05-02 13:16 ` Wander Lairson Costa
2022-05-02 16:05 ` Sathyanarayanan Kuppuswamy
Reply instructions:
You may reply publicly 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=20220509153534.i6v4xcb2g24ia2i4@black.fi.intel.com \
--to=kirill.shutemov@linux.intel.com \
--cc=ak@linux.intel.com \
--cc=bp@alien8.de \
--cc=dave.hansen@intel.com \
--cc=dave.hansen@linux.intel.com \
--cc=hpa@zytor.com \
--cc=isaku.yamahata@gmail.com \
--cc=kai.huang@intel.com \
--cc=khalid.elmously@canonical.com \
--cc=kirill@shutemov.name \
--cc=linux-kernel@vger.kernel.org \
--cc=marcelo.cerri@canonical.com \
--cc=mingo@redhat.com \
--cc=philip.cox@canonical.com \
--cc=sathyanarayanan.kuppuswamy@linux.intel.com \
--cc=tglx@linutronix.de \
--cc=tim.gardner@canonical.com \
--cc=tony.luck@intel.com \
--cc=wander@redhat.com \
--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
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).