From: Paolo Bonzini <pbonzini@redhat.com>
To: Xiaoyao Li <xiaoyao.li@intel.com>
Cc: "Zhao Liu" <zhao1.liu@intel.com>,
"Philippe Mathieu-Daudé" <philmd@linaro.org>,
"Dongli Zhang" <dongli.zhang@oracle.com>,
"Thomas Huth" <thuth@redhat.com>,
qemu-devel <qemu-devel@nongnu.org>,
"Alistair Francis" <alistair.francis@wdc.com>,
"Like Xu" <like.xu.linux@gmail.com>,
"Igor Mammedov" <imammedo@redhat.com>
Subject: Re: [Regression] Re: [PULL 35/35] qom: reverse order of instance_post_init calls
Date: Wed, 2 Jul 2025 08:12:25 -0400 [thread overview]
Message-ID: <CABgObfY-sDqw3kPSgr8b3OycA2wZVYQLcxcavierdbr-U0S_Dw@mail.gmail.com> (raw)
In-Reply-To: <76f8e877-e203-421f-b301-4b321534bd8b@intel.com>
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Il mer 2 lug 2025, 07:42 Xiaoyao Li <xiaoyao.li@intel.com> ha scritto:
> Back to Paolo's example of "a compat property will be set on a device
> *after* the class's post_init callback has run". I think the behavior of
> compat property is applied after the class's post_init callback is also
> what we want. If reversing the order, then compat prop can be
> overwritten by subclass's post_init callback, and doesn't it fail the
> purpose of compat prop?
>
I wrote the patch because of a latent issue with TDX. The issue was roughly
that a compat property was overwriting the TDX-specific modifications to
CPUID. I think this case shows that you *do* want the subclass to overwrite
the compat property—of course the subclass code must be aware that compat
properties exist and limit changes appropriately.
In general I don't see how the reverse order makes sense: the subclass
knows what the superclass does, so it can do the right thing if it runs
last; but the superclass cannot know what all of its subclasses do in
post_init, so it makes less sense to run it last.
Paolo
> So I think we might revert this patch, and document clearly the reverse
> order of .post_instance_init() callback.
>
> > X86 CPUs have the issue (e.g., "vendor" doesn't work) now because
> > they - as leaf class, don't care about the property values of
> > superclass - the DeviceState. If a property is just for initialization,
> > like "vendor", it should be placed in the instance_init() instead of
> > instance_post_init().
> >
> > In addition, if other places handle it similarly, the device's
> > post_init seems pointless. :-(
> >
> > Thanks,
> > Zhao
> >
>
>
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next prev parent reply other threads:[~2025-07-02 12:13 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-05-20 11:04 [PULL 00/35] RISCV, i386, endianness fixes for 2025-05-20 Paolo Bonzini
2025-05-20 11:04 ` [PULL 01/35] i386/tcg: Make CPUID_HT and CPUID_EXT3_CMP_LEG supported Paolo Bonzini
2025-05-20 11:04 ` [PULL 02/35] i386/hvf: Make CPUID_HT supported Paolo Bonzini
2025-05-20 11:04 ` [PULL 03/35] hw/pci-host/gt64120: Fix endianness handling Paolo Bonzini
2025-05-20 11:04 ` [PULL 04/35] hw/pci-host: Remove unused pci_host_data_be_ops Paolo Bonzini
2025-05-20 11:05 ` [PULL 05/35] qapi/misc-target: Rename SGXEPCSection to SgxEpcSection Paolo Bonzini
2025-05-20 11:05 ` [PULL 06/35] qapi/misc-target: Rename SGXInfo to SgxInfo Paolo Bonzini
2025-05-20 11:05 ` [PULL 07/35] qapi/misc-target: Fix the doc related SGXEPCSection Paolo Bonzini
2025-05-20 11:05 ` [PULL 08/35] qapi/misc-target: Fix the doc to distinguish query-sgx and query-sgx-capabilities Paolo Bonzini
2025-05-20 11:05 ` [PULL 09/35] hw/riscv: acpi: only create RHCT MMU entry for supported types Paolo Bonzini
2025-05-20 11:05 ` [PULL 10/35] target/riscv: assert argument to set_satp_mode_max_supported is valid Paolo Bonzini
2025-05-20 11:05 ` [PULL 11/35] target/riscv: cpu: store max SATP mode as a single integer Paolo Bonzini
2025-05-20 11:05 ` [PULL 12/35] target/riscv: update max_satp_mode based on QOM properties Paolo Bonzini
2025-05-20 11:05 ` [PULL 13/35] target/riscv: remove supported from RISCVSATPMap Paolo Bonzini
2025-05-20 11:05 ` [PULL 14/35] target/riscv: move satp_mode.{map, init} out of CPUConfig Paolo Bonzini via
2025-05-20 11:05 ` [PULL 15/35] target/riscv: introduce RISCVCPUDef Paolo Bonzini
2025-05-20 11:05 ` [PULL 16/35] target/riscv: store RISCVCPUDef struct directly in the class Paolo Bonzini
2025-05-20 11:05 ` [PULL 17/35] target/riscv: merge riscv_cpu_class_init with the class_base function Paolo Bonzini
2025-05-20 11:05 ` [PULL 18/35] target/riscv: move RISCVCPUConfig fields to a header file Paolo Bonzini
2025-05-20 11:05 ` [PULL 19/35] target/riscv: include default value in cpu_cfg_fields.h.inc Paolo Bonzini
2025-05-20 11:05 ` [PULL 20/35] target/riscv: add more RISCVCPUDef fields Paolo Bonzini
2025-05-20 11:05 ` [PULL 21/35] target/riscv: convert abstract CPU classes to RISCVCPUDef Paolo Bonzini
2025-05-20 11:05 ` [PULL 22/35] target/riscv: convert profile CPU models " Paolo Bonzini
2025-05-20 11:05 ` [PULL 23/35] target/riscv: convert bare " Paolo Bonzini
2025-05-20 11:05 ` [PULL 24/35] target/riscv: convert dynamic " Paolo Bonzini
2025-05-20 11:05 ` [PULL 25/35] target/riscv: convert SiFive E " Paolo Bonzini
2025-05-20 11:05 ` [PULL 26/35] target/riscv: convert ibex " Paolo Bonzini
2025-05-20 11:05 ` [PULL 27/35] target/riscv: convert SiFive U " Paolo Bonzini
2025-05-20 11:05 ` [PULL 28/35] target/riscv: th: make CSR insertion test a bit more intuitive Paolo Bonzini
2025-05-20 11:05 ` [PULL 29/35] target/riscv: generalize custom CSR functionality Paolo Bonzini
2025-05-20 11:05 ` [PULL 30/35] target/riscv: convert THead C906 to RISCVCPUDef Paolo Bonzini
2025-05-20 11:05 ` [PULL 31/35] target/riscv: convert TT Ascalon " Paolo Bonzini
2025-05-20 11:05 ` [PULL 32/35] target/riscv: convert Ventana V1 " Paolo Bonzini
2025-05-20 11:05 ` [PULL 33/35] target/riscv: convert Xiangshan Nanhu " Paolo Bonzini
2025-05-20 11:05 ` [PULL 34/35] target/riscv: remove .instance_post_init Paolo Bonzini
2025-05-20 11:05 ` [PULL 35/35] qom: reverse order of instance_post_init calls Paolo Bonzini
2025-06-23 16:56 ` [Regression] " Dongli Zhang
2025-06-24 8:57 ` Zhao Liu
2025-06-30 15:22 ` Zhao Liu
2025-07-01 6:50 ` Xiaoyao Li
2025-07-02 6:54 ` Philippe Mathieu-Daudé
2025-07-02 7:56 ` Zhao Liu
2025-07-02 11:42 ` Xiaoyao Li
2025-07-02 12:12 ` Paolo Bonzini [this message]
2025-07-02 13:24 ` Xiaoyao Li
2025-07-02 18:54 ` Paolo Bonzini
2025-07-03 1:03 ` Xiaoyao Li
2025-07-03 3:08 ` Zhao Liu
2025-07-03 3:36 ` Xiaoyao Li
2025-07-03 4:51 ` Paolo Bonzini
2025-07-07 15:41 ` Paolo Bonzini
2025-07-02 12:06 ` Paolo Bonzini
2025-05-21 14:06 ` [PULL 00/35] RISCV, i386, endianness fixes for 2025-05-20 Stefan Hajnoczi
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