Files
linux/arch
Maxim Levitsky fd92bd3b44 KVM: SVM: switch to raw spinlock for svm->ir_list_lock
Use a raw spinlock for vcpu_svm.ir_list_lock as the lock can be taken
during schedule() via kvm_sched_out() => __avic_vcpu_put(), and "normal"
spinlocks are sleepable locks when PREEMPT_RT=y.

This fixes the following lockdep warning:

  =============================
  [ BUG: Invalid wait context ]
  6.12.0-146.1640_2124176644.el10.x86_64+debug #1 Not tainted
  -----------------------------
  qemu-kvm/38299 is trying to lock:
  ff11000239725600 (&svm->ir_list_lock){....}-{3:3}, at: __avic_vcpu_put+0xfd/0x300 [kvm_amd]
  other info that might help us debug this:
  context-{5:5}
  2 locks held by qemu-kvm/38299:
   #0: ff11000239723ba8 (&vcpu->mutex){+.+.}-{4:4}, at: kvm_vcpu_ioctl+0x240/0xe00 [kvm]
   #1: ff11000b906056d8 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2e/0x130
  stack backtrace:
  CPU: 1 UID: 0 PID: 38299 Comm: qemu-kvm Kdump: loaded Not tainted 6.12.0-146.1640_2124176644.el10.x86_64+debug #1 PREEMPT(voluntary)
  Hardware name: AMD Corporation QUARTZ/QUARTZ, BIOS RQZ100AB 09/14/2023
  Call Trace:
   <TASK>
   dump_stack_lvl+0x6f/0xb0
   __lock_acquire+0x921/0xb80
   lock_acquire.part.0+0xbe/0x270
   _raw_spin_lock_irqsave+0x46/0x90
   __avic_vcpu_put+0xfd/0x300 [kvm_amd]
   svm_vcpu_put+0xfa/0x130 [kvm_amd]
   kvm_arch_vcpu_put+0x48c/0x790 [kvm]
   kvm_sched_out+0x161/0x1c0 [kvm]
   prepare_task_switch+0x36b/0xf60
   __schedule+0x4f7/0x1890
   schedule+0xd4/0x260
   xfer_to_guest_mode_handle_work+0x54/0xc0
   vcpu_run+0x69a/0xa70 [kvm]
   kvm_arch_vcpu_ioctl_run+0xdc0/0x17e0 [kvm]
   kvm_vcpu_ioctl+0x39f/0xe00 [kvm]

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Link: https://patch.msgid.link/20251030194130.307900-1-mlevitsk@redhat.com
[sean: massage changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>
2025-11-04 09:14:28 -08:00
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