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KVM: x86: ioapic: Use old_dest_mode consistently in ioapic_write_indirect()

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When reconstructing a temporary IRQ state from the historical/old IOAPIC
redirection table configuration in ioapic_write_indirect(), the code
previously assigned 'irq.dest_id' from 'old_dest_id', but incorrectly
queried the live/new 'e->fields.dest_mode' to populate 'irq.dest_mode'.

Mixing the old destination ID with the new destination mode creates an
inconsistent, hybrid IRQ state. This discrepancy leads to an incorrect
vCPU bitmap calculation via kvm_bitmap_or_dest_vcpus(), causing subsequent
interrupt routing updates (such as RTC interrupt handling) to target the
wrong set of virtual processors if both fields were modified simultaneously.

Fix this by using 'old_dest_mode' consistently alongside 'old_dest_id' to
ensure the historical IRQ structure is reconstructed accurately.

Fixes: c96001c570 ("KVM: X86: Use APIC_DEST_* macros properly in kvm_lapic_irq.dest_mode")
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Link: https://patch.msgid.link/20260528031624.1929-1-lirongqing@baidu.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Li RongQing 2026-05-27 23:16:24 -04:00 committed by Sean Christopherson
parent c3647e582e
commit 555aa0e83b
1 changed files with 1 additions and 1 deletions
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2
arch/x86/kvm/ioapic.c
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@ -441,7 +441,7 @@ static void ioapic_write_indirect(struct kvm_ioapic *ioapic, u32 val)
irq.dest_id = old_dest_id;
irq.dest_mode =
kvm_lapic_irq_dest_mode(
!!e->fields.dest_mode);
!!old_dest_mode);
kvm_bitmap_or_dest_vcpus(ioapic->kvm, &irq,
vcpu_bitmap);
}