[PATCH v4 0/5] KVM: lockdep improvements

Maxim Levitsky
2025-04-30T20:30:32Z

This is a continuation of my 'extract lock_all_vcpus/unlock_all_vcpus'
patch series.

Implement the suggestion of using lockdep's "nest_lock" feature
when locking all KVM vCPUs by adding mutex_trylock_nest_lock() and
mutex_lock_killable_nest_lock() and use these functions in the
implementation of the
kvm_trylock_all_vcpus()/kvm_lock_all_vcpus()/kvm_unlock_all_vcpus().

Those changes allow removal of a custom workaround that was needed to
silence the lockdep warning in the SEV code and also stop lockdep from
complaining in case of ARM and RISC-V code which doesn't include the above
mentioned workaround.

Finally, it's worth noting that this patch series removes a fair
amount of duplicate code by implementing the logic in one place.

Best regards,
Maxim Levitsky

Maxim Levitsky (5):
locking/mutex: implement mutex_trylock_nested
arm64: KVM: use mutex_trylock_nest_lock when locking all vCPUs
RISC-V: KVM: switch to kvm_trylock/unlock_all_vcpus
locking/mutex: implement mutex_lock_killable_nest_lock
x86: KVM: SEV: implement kvm_lock_all_vcpus and use it

arch/arm64/include/asm/kvm_host.h | 3 --
arch/arm64/kvm/arch_timer.c | 4 +-
arch/arm64/kvm/arm.c | 43 ----------------
arch/arm64/kvm/vgic/vgic-init.c | 4 +-
arch/arm64/kvm/vgic/vgic-its.c | 8 +--
arch/arm64/kvm/vgic/vgic-kvm-device.c | 12 ++---
arch/riscv/kvm/aia_device.c | 34 +------------
arch/x86/kvm/svm/sev.c | 72 ++-------------------------
include/linux/kvm_host.h | 4 ++
include/linux/mutex.h | 32 ++++++++++--
kernel/locking/mutex.c | 21 +++++---
virt/kvm/kvm_main.c | 59 ++++++++++++++++++++++
12 files changed, 126 insertions(+), 170 deletions(-)

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2.46.0