[PATCH v5 0/3] LoongArch: KVM: irqchip fixes

[Tao Cui <cui.tao@linux.dev>]

From: Tao Cui <cuitao@kylinos.cn>

Hi,

Three fixes for the LoongArch KVM irqchip code:

- Patch 1 clears the device pointer in the destroy callbacks: when
  KVM_CREATE_DEVICE succeeds but the following fd allocation fails
  (e.g. under RLIMIT_NOFILE), ops->destroy() frees the irqchip while
  kvm->arch.* still points to it.

- Patch 2 aligns kvm_pch_pic_create() with kvm_eiointc_create() by
  propagating the real error code; the kvm_ipi_create() counterpart is
  being fixed separately (Chaithanya Lagisetty).

- Patch 3 rejects repeated PCH-PIC CTRL_INIT with -EEXIST, using the
  initialized state of the kvm_io_device as the indicator.  The check,
  the MMIO base update and the bus registration are serialized by
  slots_lock; on a registration failure the state is rolled back so
  that a retry can start over.

All patches carry Fixes tags.

Changes in v5:

- Patch 3: roll back the base and the device state on registration
  failure, as suggested by Bibo.

Changes in v4:

- Patch 3: update pch_pic_base unconditionally, as suggested by
  Huacai.

Changes in v3:

- Drop "Load dmsintc pointer once in pch_msi_set_irq" (v2 patch 2),
  suggested by Bibo and Huacai.

- Patch 3 (v2 patch 4): reject repeated CTRL_INIT by checking the
  kvm_io_device state instead of a separate has_init flag, also
  suggested by Huacai; the check stays under slots_lock.

Changes in v2:

- Drop "Guard against NULL irqchip in irq injection" (v1 patch 2) and
  "Rebase steal time counter in vcpu context" (v1 patch 4) after
  review discussion: their trigger scenarios are not reachable
  through real VMM behaviour.

- Use the one-line destroy style in dmsintc suggested by Bibo.

- Track repeated PCH-PIC CTRL_INIT with a has_init flag and return
  -EEXIST instead of -EBUSY, also suggested by Bibo; move the check
  and base update under slots_lock so they are atomic.

- Add READ_ONCE() to the dmsintc pointer loads so the compiler
  keeps each of them a single load.

Tao Cui (3):
  LoongArch: KVM: Clear device pointer in irqchip destroy callbacks
  LoongArch: KVM: Propagate real error code in kvm_pch_pic_create
  LoongArch: KVM: Reject repeated PCH-PIC CTRL_INIT

 arch/loongarch/kvm/intc/dmsintc.c |  1 +
 arch/loongarch/kvm/intc/eiointc.c |  1 +
 arch/loongarch/kvm/intc/ipi.c     |  1 +
 arch/loongarch/kvm/intc/pch_pic.c | 19 +++++++++++++++----
 4 files changed, 18 insertions(+), 4 deletions(-)

-- 
2.43.0