From: "Philippe Mathieu-Daudé" <philmd@linaro.org>
To: "Cédric Le Goater" <clg@kaod.org>,
"Fabiano Rosas" <farosas@suse.de>,
qemu-devel@nongnu.org, "Juan Quintela" <quintela@redhat.com>
Cc: "Paolo Bonzini" <pbonzini@redhat.com>,
"Tyrone Ting" <kfting@nuvoton.com>,
"Alex Bennée" <alex.bennee@linaro.org>,
"Manos Pitsidianakis" <manos.pitsidianakis@linaro.org>,
"Eduardo Habkost" <eduardo@habkost.net>,
"Joel Stanley" <joel@jms.id.au>,
"Alistair Francis" <alistair@alistair23.me>,
"Anton Johansson" <anjo@rev.ng>,
"Andrey Smirnov" <andrew.smirnov@gmail.com>,
"Peter Maydell" <peter.maydell@linaro.org>,
"Hao Wu" <wuhaotsh@google.com>,
"Jean-Christophe Dubois" <jcd@tribudubois.net>,
"Igor Mitsyanko" <i.mitsyanko@gmail.com>,
"Edgar E. Iglesias" <edgar.iglesias@gmail.com>,
"Andrew Jeffery" <andrew@codeconstruct.com.au>,
"Rob Herring" <robh@kernel.org>,
qemu-arm@nongnu.org,
"Mark Cave-Ayland" <mark.cave-ayland@ilande.co.uk>,
"Peter Xu" <peterx@redhat.com>
Subject: Re: [PATCH 00/33] hw/cpu/arm: Remove one use of qemu_get_cpu() in A7/A15 MPCore priv
Date: Tue, 9 Jan 2024 22:07:07 +0100 [thread overview]
Message-ID: <e2a282a5-b92a-439e-9ecf-3ea1f74deb25@linaro.org> (raw)
In-Reply-To: <d5c0b9fb-8b09-4f68-b3ab-c8adffd484a9@kaod.org>
Hi Cédric,
On 9/1/24 19:06, Cédric Le Goater wrote:
> On 1/9/24 18:40, Fabiano Rosas wrote:
>> Cédric Le Goater <clg@kaod.org> writes:
>>
>>> On 1/3/24 20:53, Fabiano Rosas wrote:
>>>> Philippe Mathieu-Daudé <philmd@linaro.org> writes:
>>>>
>>>>> +Peter/Fabiano
>>>>>
>>>>> On 2/1/24 17:41, Cédric Le Goater wrote:
>>>>>> On 1/2/24 17:15, Philippe Mathieu-Daudé wrote:
>>>>>>> Hi Cédric,
>>>>>>>
>>>>>>> On 2/1/24 15:55, Cédric Le Goater wrote:
>>>>>>>> On 12/12/23 17:29, Philippe Mathieu-Daudé wrote:
>>>>>>>>> Hi,
>>>>>>>>>
>>>>>>>>> When a MPCore cluster is used, the Cortex-A cores belong the the
>>>>>>>>> cluster container, not to the board/soc layer. This series move
>>>>>>>>> the creation of vCPUs to the MPCore private container.
>>>>>>>>>
>>>>>>>>> Doing so we consolidate the QOM model, moving common code in a
>>>>>>>>> central place (abstract MPCore parent).
>>>>>>>>
>>>>>>>> Changing the QOM hierarchy has an impact on the state of the
>>>>>>>> machine
>>>>>>>> and some fixups are then required to maintain migration
>>>>>>>> compatibility.
>>>>>>>> This can become a real headache for KVM machines like virt for
>>>>>>>> which
>>>>>>>> migration compatibility is a feature, less for emulated ones.
>>>>>>>
>>>>>>> All changes are either moving properties (which are not migrated)
>>>>>>> or moving non-migrated QOM members (i.e. pointers of ARMCPU, which
>>>>>>> is still migrated elsewhere). So I don't see any obvious migration
>>>>>>> problem, but I might be missing something, so I Cc'ed Juan :>
>>>>
>>>> FWIW, I didn't spot anything problematic either.
>>>>
>>>> I've ran this through my migration compatibility series [1] and it
>>>> doesn't regress aarch64 migration from/to 8.2. The tests use '-M
>>>> virt -cpu max', so the cortex-a7 and cortex-a15 are not covered. I
>>>> don't
>>>> think we even support migration of anything non-KVM on arm.
>>>
>>> it happens we do.
>>>
>>
>> Oh, sorry, I didn't mean TCG here. Probably meant to say something like
>> non-KVM-capable cpus, as in 32-bit. Nevermind.
>
> Theoretically, we should be able to migrate to a TCG guest. Well, this
> worked in the past for PPC. When I was doing more KVM related changes,
> this was very useful for dev. Also, some machines are partially emulated.
> Anyhow I agree this is not a strong requirement and we often break it.
> Let's focus on KVM only.
No no, we want the same for TCG.
>>>> 1- https://gitlab.com/farosas/qemu/-/jobs/5853599533
>>>
>>> yes it depends on the QOM hierarchy and virt seems immune to the
>>> changes.
>>> Good.
>>>
>>> However, changing the QOM topology clearly breaks migration compat,
>>
>> Well, "clearly" is relative =) You've mentioned pseries and aspeed
>> already, do you have a pointer to one of those cases were we broke
>> migration
>
> Regarding pseries, migration compat broke because of 5bc8d26de20c
> ("spapr: allocate the ICPState object from under sPAPRCPUCore") which
> is similar to the changes proposed by this series, it impacts the QOM
> hierarchy. Here is the workaround/fix from Greg : 46f7afa37096
> ("spapr: fix migration of ICPState objects from/to older QEMU") which
> is quite an headache and this turned out to raise another problem some
> months ago ... :/ That's why I sent [1] to prepare removal of old
> machines and workarounds becoming a burden.
>
> Regarding aspeed, this series breaks compat.
Can you write down the steps to reproduce please? I'll debug it.
We need to understand this.
> Not that we care much
> but this caught my attention because of my past experience on pseries.
> Same kind of QOM change which could impact other machines, like virt.
> Since you checked that migration compat is preserved on virt, we should
> be fine.
>
> Thanks,
>
> C.
>
> [1]
> https://lore.kernel.org/qemu-devel/20231214181723.1520854-1-clg@kaod.org/
>
next prev parent reply other threads:[~2024-01-09 21:08 UTC|newest]
Thread overview: 76+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-12 16:29 [PATCH 00/33] hw/cpu/arm: Remove one use of qemu_get_cpu() in A7/A15 MPCore priv Philippe Mathieu-Daudé
2023-12-12 16:29 ` [PATCH 01/33] hw/arm/boot: Propagate vCPU to arm_load_dtb() Philippe Mathieu-Daudé
2024-01-02 13:51 ` Cédric Le Goater
2023-12-12 16:29 ` [PATCH 02/33] hw/arm/fsl-imx6: Add a local 'gic' variable Philippe Mathieu-Daudé
2024-01-02 13:52 ` Cédric Le Goater
2023-12-12 16:29 ` [PATCH 03/33] hw/arm/fsl-imx6ul: " Philippe Mathieu-Daudé
2024-01-02 13:52 ` Cédric Le Goater
2023-12-12 16:29 ` [PATCH 04/33] hw/arm/fsl-imx7: " Philippe Mathieu-Daudé
2024-01-02 13:53 ` Cédric Le Goater
2023-12-12 16:29 ` [PATCH 05/33] hw/cpu: Remove dead Kconfig Philippe Mathieu-Daudé
2024-01-02 13:53 ` Cédric Le Goater
2023-12-12 16:29 ` [PATCH 06/33] hw/cpu/arm: Rename 'busdev' -> 'gicsbd' in a15mp_priv_realize() Philippe Mathieu-Daudé
2024-01-02 13:54 ` Cédric Le Goater
2023-12-12 16:29 ` [PATCH 07/33] hw/cpu/arm: Alias 'num-cpu' property on TYPE_REALVIEW_MPCORE Philippe Mathieu-Daudé
2024-01-02 13:57 ` Cédric Le Goater
2023-12-12 16:29 ` [PATCH 08/33] hw/cpu/arm: Declare CPU QOM types using DEFINE_TYPES() macro Philippe Mathieu-Daudé
2024-01-02 13:57 ` Cédric Le Goater
2023-12-12 16:29 ` [PATCH 09/33] hw/cpu/arm: Merge {a9mpcore.h, a15mpcore.h} as cortex_mpcore.h Philippe Mathieu-Daudé
2024-01-02 14:00 ` Cédric Le Goater
2023-12-12 16:29 ` [PATCH 10/33] hw/cpu/arm: Introduce abstract CORTEX_MPCORE_PRIV QOM type Philippe Mathieu-Daudé
2024-01-02 14:23 ` Cédric Le Goater
2023-12-12 16:29 ` [PATCH 11/33] hw/cpu/arm: Have A9MPCORE/A15MPCORE inheritate common CORTEX_MPCORE_PRIV Philippe Mathieu-Daudé
2024-01-02 14:23 ` Cédric Le Goater
2023-12-12 16:29 ` [PATCH 12/33] hw/cpu/arm: Create MPCore container in QOM parent Philippe Mathieu-Daudé
2024-01-02 14:23 ` Cédric Le Goater
2023-12-12 16:29 ` [PATCH 13/33] hw/cpu/arm: Handle 'num_cores' property once in MPCore parent Philippe Mathieu-Daudé
2023-12-12 16:29 ` [PATCH 14/33] hw/cpu/arm: Handle 'has_el2/3' properties " Philippe Mathieu-Daudé
2024-01-12 21:33 ` Fabiano Rosas
2024-01-16 16:25 ` Philippe Mathieu-Daudé
2023-12-12 16:29 ` [PATCH 15/33] hw/cpu/arm: Handle 'gic-irq' property " Philippe Mathieu-Daudé
2023-12-12 16:29 ` [PATCH 16/33] hw/cpu/arm: Handle GIC " Philippe Mathieu-Daudé
2023-12-12 16:29 ` [PATCH 17/33] hw/cpu/arm: Document more properties of CORTEX_MPCORE_PRIV QOM type Philippe Mathieu-Daudé
2023-12-12 16:29 ` [PATCH 18/33] hw/cpu/arm: Replace A15MPPrivState by CortexMPPrivState Philippe Mathieu-Daudé
2023-12-12 16:29 ` [PATCH 19/33] hw/cpu/arm: Introduce TYPE_A7MPCORE_PRIV for Cortex-A7 MPCore Philippe Mathieu-Daudé
2023-12-12 16:29 ` [PATCH 20/33] hw/cpu/arm: Consolidate check on max GIC spi supported Philippe Mathieu-Daudé
2023-12-12 16:29 ` [PATCH 21/33] hw/cpu/arm: Create CPUs once in MPCore parent Philippe Mathieu-Daudé
2023-12-12 16:29 ` [PATCH 22/33] hw/arm/aspeed_ast2600: Let the A7MPcore create/wire the CPU cores Philippe Mathieu-Daudé
2024-01-02 0:11 ` Andrew Jeffery
2023-12-12 16:29 ` [PATCH 23/33] hw/arm/exynos4210: Let the A9MPcore " Philippe Mathieu-Daudé
2023-12-12 16:29 ` [PATCH 24/33] hw/arm/fsl-imx6: " Philippe Mathieu-Daudé
2023-12-12 16:29 ` [PATCH 25/33] hw/arm/fsl-imx6ul: Let the A7MPcore " Philippe Mathieu-Daudé
2023-12-12 16:29 ` [PATCH 26/33] hw/arm/fsl-imx7: " Philippe Mathieu-Daudé
2023-12-12 16:29 ` [PATCH 27/33] hw/arm/highbank: Let the A9/A15MPcore " Philippe Mathieu-Daudé
2023-12-12 16:29 ` [PATCH 28/33] hw/arm/vexpress: " Philippe Mathieu-Daudé
2023-12-12 16:29 ` [PATCH 29/33] hw/arm/xilinx_zynq: Let the A9MPcore " Philippe Mathieu-Daudé
2023-12-12 16:29 ` [PATCH 30/33] hw/arm/npcm7xx: " Philippe Mathieu-Daudé
2023-12-12 16:29 ` [PATCH 31/33] hw/cpu/a9mpcore: Remove legacy code Philippe Mathieu-Daudé
2023-12-12 16:29 ` [PATCH 32/33] hw/cpu/arm: Remove 'num-cpu' property alias Philippe Mathieu-Daudé
2023-12-12 16:29 ` [PATCH 33/33] hw/cpu/arm: Remove use of qemu_get_cpu() in A7/A15 realize() Philippe Mathieu-Daudé
2023-12-26 11:17 ` [PATCH 00/33] hw/cpu/arm: Remove one use of qemu_get_cpu() in A7/A15 MPCore priv Philippe Mathieu-Daudé
2024-01-02 14:55 ` Cédric Le Goater
2024-01-02 16:15 ` Philippe Mathieu-Daudé
2024-01-02 16:41 ` Cédric Le Goater
2024-01-03 9:19 ` Philippe Mathieu-Daudé
2024-01-03 19:53 ` Fabiano Rosas
2024-01-09 15:02 ` Cédric Le Goater
2024-01-09 17:40 ` Fabiano Rosas
2024-01-09 18:06 ` Cédric Le Goater
2024-01-09 20:21 ` Fabiano Rosas
2024-01-09 21:22 ` Philippe Mathieu-Daudé
2024-01-10 3:36 ` Peter Xu
2024-01-10 6:03 ` Markus Armbruster
2024-01-10 6:26 ` Peter Xu
2024-01-10 8:09 ` Markus Armbruster
2024-01-10 8:44 ` Peter Xu
2024-01-12 9:03 ` Cédric Le Goater
2024-01-10 13:19 ` Fabiano Rosas
2024-01-10 13:54 ` Markus Armbruster
2024-01-12 10:26 ` Cédric Le Goater
2024-01-12 19:54 ` Fabiano Rosas
2024-01-15 9:04 ` Cédric Le Goater
2024-01-12 8:41 ` Cédric Le Goater
2024-01-09 21:07 ` Philippe Mathieu-Daudé [this message]
2024-01-09 21:09 ` Philippe Mathieu-Daudé
2024-01-12 8:00 ` Cédric Le Goater
2024-01-12 7:29 ` Cédric Le Goater
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