61 lines
2.3 KiB
Diff
61 lines
2.3 KiB
Diff
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From: Greg Kurz <groug@kaod.org>
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Date: Fri, 9 Apr 2021 18:03:39 +0200
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Subject: cpu/core: Fix "help" of CPU core device types
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Git-commit: 0b47ec4b95ad1952e55e639711d442f8ec6e1345
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Calling qdev_get_machine() from a QOM instance_init function is
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fragile because we can't be sure the machine object actually
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exists. And this happens to break when passing ",help" on the
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command line to get the list of properties for a CPU core
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device types :
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$ ./qemu-system-ppc64 -device power8_v2.0-spapr-cpu-core,help
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qemu-system-ppc64: ../../hw/core/machine.c:1290:
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qdev_get_machine: Assertion `machine != NULL' failed.
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Aborted (core dumped)
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This used to work before QEMU 5.0, but commit 3df261b6676b
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unwillingly introduced a subtle regression : the above command
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line needs to create an instance but the instance_init function
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of the base class calls qdev_get_machine() before
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qemu_create_machine() has been called, which is a programming bug.
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Use current_machine instead. It is okay to skip the setting of
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nr_thread in this case since only its type is displayed.
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Fixes: 3df261b6676b ("softmmu/vl.c: Handle '-cpu help' and '-device help' before 'no default machine'")
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Reported-by: Thomas Huth <thuth@redhat.com>
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Signed-off-by: Greg Kurz <groug@kaod.org>
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Cc: peter.maydell@linaro.org
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Message-Id: <20210409160339.500167-3-groug@kaod.org>
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Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
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Signed-off-by: Bruce Rogers <brogers@suse.com>
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---
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hw/cpu/core.c | 10 ++++++++--
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1 file changed, 8 insertions(+), 2 deletions(-)
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diff --git a/hw/cpu/core.c b/hw/cpu/core.c
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index 92d3b2fbad62cc3dd7656f148bfd..9876075155743d8966a8383412fd 100644
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--- a/hw/cpu/core.c
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+++ b/hw/cpu/core.c
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@@ -66,10 +66,16 @@ static void core_prop_set_nr_threads(Object *obj, Visitor *v, const char *name,
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static void cpu_core_instance_init(Object *obj)
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{
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- MachineState *ms = MACHINE(qdev_get_machine());
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CPUCore *core = CPU_CORE(obj);
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- core->nr_threads = ms->smp.threads;
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+ /*
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+ * Only '-device something-cpu-core,help' can get us there before
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+ * the machine has been created. We don't care to set nr_threads
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+ * in this case since it isn't used afterwards.
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+ */
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+ if (current_machine) {
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+ core->nr_threads = current_machine->smp.threads;
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+ }
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}
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static void cpu_core_class_init(ObjectClass *oc, void *data)
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