From: Julien Grall <julien@xen.org>
To: Andrew Cooper <andrew.cooper3@citrix.com>,
Stefano Stabellini <sstabellini@kernel.org>
Cc: "Oleksandr Tyshchenko" <olekstysh@gmail.com>,
xen-devel@lists.xenproject.org,
"Ian Jackson" <iwj@xenproject.org>,
"Oleksandr Tyshchenko" <oleksandr_tyshchenko@epam.com>,
"Paul Durrant" <paul@xen.org>, "Jan Beulich" <jbeulich@suse.com>,
"Roger Pau Monné" <roger.pau@citrix.com>, "Wei Liu" <wl@xen.org>,
"Julien Grall" <julien.grall@arm.com>,
"George Dunlap" <george.dunlap@citrix.com>,
"Jun Nakajima" <jun.nakajima@intel.com>,
"Kevin Tian" <kevin.tian@intel.com>, "Tim Deegan" <tim@xen.org>,
"Daniel De Graaf" <dgdegra@tycho.nsa.gov>,
"Volodymyr Babchuk" <Volodymyr_Babchuk@epam.com>,
"Bertrand Marquis" <bertrand.marquis@arm.com>,
"Wei Chen" <Wei.Chen@arm.com>, "Kaly Xin" <Kaly.Xin@arm.com>,
"Artem Mygaiev" <joculator@gmail.com>,
"Alex Bennée" <alex.bennee@linaro.org>
Subject: Re: [PATCH V5 00/22] IOREQ feature (+ virtio-mmio) on Arm
Date: Thu, 28 Jan 2021 18:21:05 +0000 [thread overview]
Message-ID: <32349c24-dc9b-8c0a-d98e-3fc39eebb9ec@xen.org> (raw)
In-Reply-To: <9d0e2e0a-4409-ee37-636b-a0403e3571fc@xen.org>
On 28/01/2021 18:16, Julien Grall wrote:
> Hi Andrew,
>
> On 28/01/2021 18:10, Andrew Cooper wrote:
>> On 28/01/2021 17:44, Julien Grall wrote:
>>>
>>>
>>> On 28/01/2021 17:24, Stefano Stabellini wrote:
>>>> On Thu, 28 Jan 2021, Julien Grall wrote:
>>>>> On 25/01/2021 19:08, Oleksandr Tyshchenko wrote:
>>>>> > Patch series [8] was rebased on recent "staging branch"
>>>>>> (5e31789 tools/ocaml/libs/xb: Do not crash after xenbus is
>>>>>> unmapped) and
>>>>>> tested on
>>>>>> Renesas Salvator-X board + H3 ES3.0 SoC (Arm64) with virtio-mmio disk
>>>>>> backend [9]
>>>>>> running in driver domain and unmodified Linux Guest running on
>>>>>> existing
>>>>>> virtio-blk driver (frontend). No issues were observed. Guest domain
>>>>>> 'reboot/destroy'
>>>>>> use-cases work properly. Patch series was only build-tested on x86.
>>>>>
>>>>> I have done basic testing with a Linux guest on x86 and I didn't
>>>>> spot any
>>>>> regression.
>>>>>
>>>>> Unfortunately, I don't have a Windows VM in hand, so I can't confirm
>>>>> if there
>>>>> is no regression there. Can anyone give a try?
>>>>>
>>>>> On a separate topic, Andrew expressed on IRC some concern to expose
>>>>> the
>>>>> bufioreq interface to other arch than x86. I will let him explain
>>>>> his view
>>>>> here.
>>>>>
>>>>> Given that IOREQ will be a tech preview on Arm (this implies the
>>>>> interface is
>>>>> not stable) on Arm, I think we can defer the discussion past the
>>>>> freeze.
>>>>
>>>> Yes, I agree that we can defer the discussion.
>>>>
>>>>
>>>>> For now, I would suggest to check if a Device Model is trying to
>>>>> create an
>>>>> IOREQ server with bufioreq is enabled (see ioreq_server_create()).
>>>>> This would
>>>>> not alleviate Andrew's concern, however it would at allow us to
>>>>> judge whether
>>>>> the buffering concept is going to be used on Arm (I can see some use
>>>>> for the
>>>>> Virtio doorbell).
>>>>>
>>>>> What do others think?
>>>>
>>>> Difficult to say. We don't have any uses today but who knows in the
>>>> future.
>>>
>>> I have some ideas, but Andrew so far objects on using the existing
>>> bufioreq interface for good reasons. It is using guest_cmpxchg() which
>>> is really expensive.
>>
>> Worse. Patch 5 needs to switch cmpxchg() to guest_cmpxchg() to avoid
>> reintroducing XSA-295, but doesn't.
>
> The memory is only shared with the emulator (we don't allow the legacy
> interface on Arm). So why do you think it is re-introducing XSA-295?
Just for clarification, the swithc to guest_cmpxchg() is done as part of
patch #13.
Cheers,
--
Julien Grall
next prev parent reply other threads:[~2021-01-28 18:21 UTC|newest]
Thread overview: 103+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-25 19:08 [PATCH V5 00/22] IOREQ feature (+ virtio-mmio) on Arm Oleksandr Tyshchenko
2021-01-25 19:08 ` [PATCH V5 01/22] x86/ioreq: Prepare IOREQ feature for making it common Oleksandr Tyshchenko
2021-01-27 16:48 ` Jan Beulich
2021-01-25 19:08 ` [PATCH V5 02/22] x86/ioreq: Add IOREQ_STATUS_* #define-s and update code for moving Oleksandr Tyshchenko
2021-01-25 19:08 ` [PATCH V5 03/22] x86/ioreq: Provide out-of-line wrapper for the handle_mmio() Oleksandr Tyshchenko
2021-01-25 19:08 ` [PATCH V5 04/22] xen/ioreq: Make x86's IOREQ feature common Oleksandr Tyshchenko
2021-01-25 23:13 ` Julien Grall
2021-01-25 23:40 ` Oleksandr
2021-01-27 18:43 ` Julien Grall
2021-01-27 20:22 ` Oleksandr
2021-01-27 20:46 ` Stefano Stabellini
2021-01-28 11:01 ` Oleksandr
2021-01-28 11:21 ` Jan Beulich
2021-01-28 12:49 ` Oleksandr
2021-01-28 17:13 ` Stefano Stabellini
2021-01-27 16:58 ` Jan Beulich
2021-01-27 20:14 ` Oleksandr
2021-01-28 8:06 ` Jan Beulich
2021-01-28 11:16 ` Oleksandr
2021-01-28 11:24 ` Jan Beulich
2021-01-25 19:08 ` [PATCH V5 05/22] xen/ioreq: Make x86's hvm_ioreq_needs_completion() common Oleksandr Tyshchenko
2021-01-25 19:08 ` [PATCH V5 06/22] xen/ioreq: Make x86's hvm_mmio_first(last)_byte() common Oleksandr Tyshchenko
2021-01-25 19:08 ` [PATCH V5 07/22] xen/ioreq: Make x86's hvm_ioreq_(page/vcpu/server) structs common Oleksandr Tyshchenko
2021-01-25 19:08 ` [PATCH V5 08/22] xen/ioreq: Move x86's ioreq_server to struct domain Oleksandr Tyshchenko
2021-01-25 19:08 ` [PATCH V5 09/22] xen/ioreq: Make x86's IOREQ related dm-op handling common Oleksandr Tyshchenko
2021-01-26 13:31 ` Paul Durrant
2021-01-28 10:52 ` Jan Beulich
2021-01-28 12:06 ` Oleksandr
2021-01-28 13:18 ` Jan Beulich
2021-01-28 20:01 ` Oleksandr
2021-01-25 19:08 ` [PATCH V5 10/22] xen/ioreq: Move x86's io_completion/io_req fields to struct vcpu Oleksandr Tyshchenko
2021-01-28 13:41 ` Julien Grall
2021-01-28 13:53 ` Jan Beulich
2021-01-28 14:21 ` Julien Grall
2021-01-28 14:36 ` Jan Beulich
2021-01-28 14:49 ` Andrew Cooper
2021-01-28 14:51 ` Ian Jackson
2021-01-28 14:54 ` Jan Beulich
2021-01-28 16:15 ` Andrew Cooper
2021-01-28 15:01 ` Julien Grall
2021-01-28 14:05 ` Oleksandr
2021-01-25 19:08 ` [PATCH V5 11/22] xen/mm: Make x86's XENMEM_resource_ioreq_server handling common Oleksandr Tyshchenko
2021-01-25 19:08 ` [PATCH V5 12/22] xen/ioreq: Remove "hvm" prefixes from involved function names Oleksandr Tyshchenko
2021-01-25 19:08 ` [PATCH V5 13/22] xen/ioreq: Use guest_cmpxchg64() instead of cmpxchg() Oleksandr Tyshchenko
2021-01-25 19:08 ` [PATCH V5 14/22] arm/ioreq: Introduce arch specific bits for IOREQ/DM features Oleksandr Tyshchenko
2021-01-25 20:19 ` Stefano Stabellini
2021-01-26 9:15 ` Jan Beulich
2021-01-27 9:54 ` Oleksandr
2021-01-27 10:15 ` Jan Beulich
2021-01-27 17:01 ` Julien Grall
2021-01-27 17:04 ` Jan Beulich
2021-01-27 18:33 ` Julien Grall
2021-01-27 19:20 ` Oleksandr
2021-01-28 9:40 ` Julien Grall
2021-01-28 11:33 ` Oleksandr
2021-01-28 13:39 ` Oleksandr
2021-01-28 14:29 ` Oleksandr
2021-01-28 14:41 ` Julien Grall
2021-01-28 14:52 ` Oleksandr
2021-01-28 15:08 ` Julien Grall
2021-01-28 17:50 ` Oleksandr
2021-01-25 19:08 ` [PATCH V5 15/22] xen/arm: Call vcpu_ioreq_handle_completion() in check_for_vcpu_work() Oleksandr Tyshchenko
2021-01-27 14:49 ` Julien Grall
2021-01-27 15:56 ` Oleksandr
2021-01-27 20:34 ` Stefano Stabellini
2021-01-25 19:08 ` [PATCH V5 16/22] xen/mm: Handle properly reference in set_foreign_p2m_entry() on Arm Oleksandr Tyshchenko
2021-01-25 19:08 ` [PATCH V5 17/22] xen/ioreq: Introduce domain_has_ioreq_server() Oleksandr Tyshchenko
2021-01-25 19:08 ` [PATCH V5 18/22] xen/dm: Introduce xendevicemodel_set_irq_level DM op Oleksandr Tyshchenko
2021-01-25 19:08 ` [PATCH V5 19/22] xen/arm: io: Abstract sign-extension Oleksandr Tyshchenko
2021-01-25 19:08 ` [PATCH V5 20/22] xen/arm: io: Harden sign extension check Oleksandr Tyshchenko
2021-01-25 19:08 ` [PATCH V5 21/22] xen/ioreq: Make x86's send_invalidate_req() common Oleksandr Tyshchenko
2021-01-25 19:08 ` [PATCH V5 22/22] xen/arm: Add mapcache invalidation handling Oleksandr Tyshchenko
2021-01-28 9:55 ` Julien Grall
2021-01-28 13:12 ` Oleksandr
2021-01-27 16:43 ` [PATCH V5 00/22] IOREQ feature (+ virtio-mmio) on Arm Julien Grall
2021-01-27 16:50 ` Oleksandr
2021-01-27 17:33 ` Julien Grall
2021-01-27 17:37 ` Oleksandr
2021-01-27 17:42 ` Julien Grall
2021-01-27 17:45 ` Oleksandr
2021-01-28 14:37 ` Oleksandr
2021-01-28 15:14 ` Julien Grall
2021-01-28 17:55 ` Oleksandr
2021-01-28 16:11 ` Julien Grall
2021-01-28 17:24 ` Stefano Stabellini
2021-01-28 17:44 ` Julien Grall
2021-01-28 18:10 ` Andrew Cooper
2021-01-28 18:16 ` Julien Grall
2021-01-28 18:21 ` Julien Grall [this message]
2021-01-28 20:10 ` Andrew Cooper
2021-01-28 21:19 ` Julien Grall
2021-01-28 19:44 ` Oleksandr
2021-01-29 1:15 ` Oleksandr
[not found] <161160798888.13183.15031685460985886988@c667a6b167f6>
2021-01-25 20:56 ` Stefano Stabellini
2021-01-25 23:20 ` Julien Grall
2021-01-26 0:14 ` Oleksandr
2021-01-27 10:13 ` Oleksandr
2021-01-27 10:51 ` Jan Beulich
2021-01-27 11:15 ` Oleksandr
2021-01-27 11:22 ` Jan Beulich
2021-01-27 11:29 ` Oleksandr
2021-01-27 15:29 ` Julien Grall
2021-01-27 15:46 ` Jan Beulich
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