Re: [PATCH RFC 00/15] vhost-user: isolated memory

This is an OpenPGP/MIME signed message (RFC 4880 and 3156)
--------------QO0gevjSZi4nSb4i04j50d10
Content-Type: multipart/mixed; boundary="------------4M1ZxfF0mO0jpR8FOg9JRcIn";
 protected-headers="v1"; hp="clear"
Message-ID: <[email protected]>
Date: Fri, 24 Jul 2026 20:15:51 -0400
MIME-Version: 1.0
User-Agent: Mozilla Thunderbird
From: Demi Marie Obenour <[email protected]>
Subject: Re: [PATCH RFC 00/15] vhost-user: isolated memory
To: ConKite <[email protected]>, [email protected]
Cc: "Michael S. Tsirkin" <[email protected]>,
 Stefano Garzarella <[email protected]>,
 =?UTF-8?Q?Alex_Benn=C3=A9e?= <[email protected]>,
 Viresh Kumar <[email protected]>, Gerd Hoffmann <[email protected]>,
 Mathieu Poirier <[email protected]>,
 Manos Pitsidianakis <[email protected]>,
 Haixu Cui <[email protected]>, Raphael Norwitz <[email protected]>,
 Kevin Wolf <[email protected]>, Hanna Reitz <[email protected]>,
 =?UTF-8?Q?Marc-Andr=C3=A9_Lureau?= <[email protected]>,
 Paolo Bonzini <[email protected]>, Fam Zheng <[email protected]>,
 Stefan Hajnoczi <[email protected]>, Milan Zamazal <[email protected]>,
 Akihiko Odaki <[email protected]>,
 Dmitry Osipenko <[email protected]>, [email protected],
 [email protected], "Gonglei (Arei)" <[email protected]>,
 zhenwei pi <[email protected]>, =?UTF-8?Q?Daniel_P=2E_Berrang=C3=A9?=
 <[email protected]>, Eric Blake <[email protected]>,
 Markus Armbruster <[email protected]>, Jason Wang <[email protected]>,
 Peter Xu <[email protected]>, =?UTF-8?Q?Eugenio_P=C3=A9rez?=
 <[email protected]>, Alyssa Ross <[email protected]>
References: <[email protected]>
Content-Language: en-US
In-Reply-To: <[email protected]>
Autocrypt: [email protected]; keydata=
 xsFNBFp+A0oBEADffj6anl9/BHhUSxGTICeVl2tob7hPDdhHNgPR4C8xlYt5q49yB+l2nipd
 aq+4Gk6FZfqC825TKl7eRpUjMriwle4r3R0ydSIGcy4M6eb0IcxmuPYfbWpr/si88QKgyGSV
 Z7GeNW1UnzTdhYHuFlk8dBSmB1fzhEYEk0RcJqg4AKoq6/3/UorR+FaSuVwT7rqzGrTlscnT
 DlPWgRzrQ3jssesI7sZLm82E3pJSgaUoCdCOlL7MMPCJwI8JpPlBedRpe9tfVyfu3euTPLPx
 wcV3L/cfWPGSL4PofBtB8NUU6QwYiQ9Hzx4xOyn67zW73/G0Q2vPPRst8LBDqlxLjbtx/WLR
 6h3nBc3eyuZ+q62HS1pJ5EvUT1vjyJ1ySrqtUXWQ4XlZyoEFUfpJxJoN0A9HCxmHGVckzTRl
 5FMWo8TCniHynNXsBtDQbabt7aNEOaAJdE7to0AH3T/Bvwzcp0ZJtBk0EM6YeMLtotUut7h2
 Bkg1b//r6bTBswMBXVJ5H44Qf0+eKeUg7whSC9qpYOzzrm7+0r9F5u3qF8ZTx55TJc2g656C
 9a1P1MYVysLvkLvS4H+crmxA/i08Tc1h+x9RRvqba4lSzZ6/Tmt60DPM5Sc4R0nSm9BBff0N
 m0bSNRS8InXdO1Aq3362QKX2NOwcL5YaStwODNyZUqF7izjK4QARAQABzTxEZW1pIE1hcmll
 IE9iZW5vdXIgKGxvdmVyIG9mIGNvZGluZykgPGRlbWlvYmVub3VyQGdtYWlsLmNvbT7CwXgE
 EwECACIFAlp+A0oCGwMGCwkIBwMCBhUIAgkKCwQWAgMBAh4BAheAAAoJELKItV//nCLBhr8Q
 AK/xrb4wyi71xII2hkFBpT59ObLN+32FQT7R3lbZRjVFjc6yMUjOb1H/hJVxx+yo5gsSj5LS
 9AwggioUSrcUKldfA/PKKai2mzTlUDxTcF3vKx6iMXKA6AqwAw4B57ZEJoMM6egm57TV19kz
 PMc879NV2nc6+elaKl+/kbVeD3qvBuEwsTe2Do3HAAdrfUG/j9erwIk6gha/Hp9yZlCnPTX+
 VK+xifQqt8RtMqS5R/S8z0msJMI/ajNU03kFjOpqrYziv6OZLJ5cuKb3bZU5aoaRQRDzkFIR
 6aqtFLTohTo20QywXwRa39uFaOT/0YMpNyel0kdOszFOykTEGI2u+kja35g9TkH90kkBTG+a
 EWttIht0Hy6YFmwjcAxisSakBuHnHuMSOiyRQLu43ej2+mDWgItLZ48Mu0C3IG1seeQDjEYP
 tqvyZ6bGkf2Vj+L6wLoLLIhRZxQOedqArIk/Sb2SzQYuxN44IDRt+3ZcDqsPppoKcxSyd1Ny
 2tpvjYJXlfKmOYLhTWs8nwlAlSHX/c/jz/ywwf7eSvGknToo1Y0VpRtoxMaKW1nvH0OeCSVJ
 itfRP7YbiRVc2aNqWPCSgtqHAuVraBRbAFLKh9d2rKFB3BmynTUpc1BQLJP8+D5oNyb8Ts4x
 Xd3iV/uD8JLGJfYZIR7oGWFLP4uZ3tkneDfYzsFNBFp+A0oBEAC9ynZI9LU+uJkMeEJeJyQ/
 8VFkCJQPQZEsIGzOTlPnwvVna0AS86n2Z+rK7R/usYs5iJCZ55/JISWd8xD57ue0eB47bcJv
 VqGlObI2DEG8TwaW0O0duRhDgzMEL4t1KdRAepIESBEA/iPpI4gfUbVEIEQuqdqQyO4GAe+M
 kD0Hy5JH/0qgFmbaSegNTdQg5iqYjRZ3ttiswalql1/iSyv1WYeC1OAs+2BLOAT2NEggSiVO
 txEfgewsQtCWi8H1SoirakIfo45Hz0tk/Ad9ZWh2PvOGt97Ka85o4TLJxgJJqGEnqcFUZnJJ
 riwoaRIS8N2C8/nEM53jb1sH0gYddMU3QxY7dYNLIUrRKQeNkF30dK7V6JRH7pleRlf+wQcN
 fRAIUrNlatj9TxwivQrKnC9aIFFHEy/0mAgtrQShcMRmMgVlRoOA5B8RTulRLCmkafvwuhs6
 dCxN0GNAORIVVFxjx9Vn7OqYPgwiofZ6SbEl0hgPyWBQvE85klFLZLoj7p+joDY1XNQztmfA
 rnJ9x+YV4igjWImINAZSlmEcYtd+xy3Li/8oeYDAqrsnrOjb+WvGhCykJk4urBog2LNtcyCj
 kTs7F+WeXGUo0NDhbd3Z6AyFfqeF7uJ3D5hlpX2nI9no/ugPrrTVoVZAgrrnNz0iZG2DVx46
 x913pVKHl5mlYQARAQABwsFfBBgBAgAJBQJafgNKAhsMAAoJELKItV//nCLBwNIP/AiIHE8b
 oIqReFQyaMzxq6lE4YZCZNj65B/nkDOvodSiwfwjjVVE2V3iEzxMHbgyTCGA67+Bo/d5aQGj
 gn0TPtsGzelyQHipaUzEyrsceUGWYoKXYyVWKEfyh0cDfnd9diAm3VeNqchtcMpoehETH8fr
 RHnJdBcjf112PzQSdKC6kqU0Q196c4Vp5HDOQfNiDnTf7gZSj0BraHOByy9LEDCLhQiCmr+2
 E0rW4tBtDAn2HkT9uf32ZGqJCn1O+2uVfFhGu6vPE5qkqrbSE8TG+03H8ecU2q50zgHWPdHM
 OBvy3EhzfAh2VmOSTcRK+tSUe/u3wdLRDPwv/DTzGI36Kgky9MsDC5gpIwNbOJP2G/q1wT1o
 Gkw4IXfWv2ufWiXqJ+k7HEi2N1sree7Dy9KBCqb+ca1vFhYPDJfhP75I/VnzHVssZ/rYZ9+5
 1yDoUABoNdJNSGUYl+Yh9Pw9pE3Kt4EFzUlFZWbE4xKL/NPno+z4J9aWemLLszcYz/u3XnbO
 vUSQHSrmfOzX3cV4yfmjM5lewgSstoxGyTx2M8enslgdXhPthZlDnTnOT+C+OTsh8+m5tos8
 HQjaPM01MKBiAqdPgksm1wu2DrrwUi6ChRVTUBcj6+/9IJ81H2P2gJk3Ls3AVIxIffLoY34E
 +MYSfkEjBz0E8CLOcAw7JIwAaeBT

--------------4M1ZxfF0mO0jpR8FOg9JRcIn
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: quoted-printable

On 7/23/26 18:29, ConKite wrote:
> This patch series implements a memory isolation mode in vhost-user. The=

> purpose of this mode is to provide the option of additional security by=

> eliminating direct access of guest memory by vhost-user devices.
> At a high level this works by:
>=20
> 1. Adding qdev and qapi properties required to enable isolation mode fo=
r
>    various devices.
> 2. Allocating an isolation memory region in an anonymous file and mappi=
ng it
>    to host memory.  This isolation region will hold the bounce buffers =
and
>    vrings necessary to move data.
> 3. Using a vhost-iova-tree to allocate and track the mapping between
>    guest regions and their corresponding bounce buffers in the isolatio=
n
>    memory.
> 4. Creating shadow virtqueues to intercept request notifications.  As
>    kick and call events are received by an svq, it copies buffer
>    contents and descriptors between isolation and guest memory before
>    notifying the backend or guest.  =20
>=20
> Note: This project is currently in a partially functional state. For
> example, in testing vhost-user-input and a keyboard, keystrokes may
> register correctly or be double counted depending on the combination
> of backend daemon and guest OS used. However, the desire is to make
> this work public at this stage for comment on the overall
> approach.

Thank you so much for the work!  I'm very excited about it.

I do have a few questions:

1. Is this dependent on the specific vhost-user device type?  In other
   words, does this code need to be specific to vhost-user-blk/net/etc
   devices?

2. What kind of performance penalty is there for isolation?  The use
   of shadow virtqueues seems relatively complex.

3. Does it make sense to have device-type-specific code to validate
   data sent back by the server?  This could protect drivers that
   trust virtio devices.=20
--=20
Sincerely,
Demi Marie Obenour (she/her/hers)


--------------4M1ZxfF0mO0jpR8FOg9JRcIn--

--------------QO0gevjSZi4nSb4i04j50d10
Content-Type: application/pgp-signature; name="OpenPGP_signature.asc"
Content-Description: OpenPGP digital signature
Content-Disposition: attachment; filename="OpenPGP_signature.asc"

-----BEGIN PGP SIGNATURE-----
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=iiNx
-----END PGP SIGNATURE-----

--------------QO0gevjSZi4nSb4i04j50d10--