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acpi: mark PMTIMER as unlocked

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Reading QEMU_CLOCK_VIRTUAL is thread-safe, write access is NOP.

This makes possible to boot Windows with large vCPUs count when
hv-time is not used.

Reproducer:
  -M q35,hpet=off -cpu host -enable-kvm -smp 240,sockets=4 -m 8G WS2025.img
fails to boot within 30min.

With this fix it boots within 2-1min.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Link: https://lore.kernel.org/r/20250814160600.2327672-3-imammedo@redhat.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Igor Mammedov 2025-08-14 18:05:54 +02:00 • committed by Paolo Bonzini
parent 73c520b088
commit 4ae5e2b2bf
1 changed files with 1 additions and 0 deletions
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1
hw/acpi/core.c
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@ -547,6 +547,7 @@ void acpi_pm_tmr_init(ACPIREGS *ar, acpi_update_sci_fn update_sci,
ar->tmr.timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, acpi_pm_tmr_timer, ar);
memory_region_init_io(&ar->tmr.io, memory_region_owner(parent),
&acpi_pm_tmr_ops, ar, "acpi-tmr", 4);
memory_region_enable_lockless_io(&ar->tmr.io);
memory_region_add_subregion(parent, 8, &ar->tmr.io);
}