[PATCH v3 00/10] KVM: arm64: Avoid serializing LPI get() / put()

Oliver Upton
2024-02-16T18:42:07Z

As discussed, here is a slimmed-down series for addressing lock
serialization in the vgic_get_irq() / vgic_put_irq() path for LPIs. The
bulk of it is using an xarray to represent LPIs and leveraging RCU to
avoid serializing readers of the LPI configuration state.

There's a lot of potential for clean-up, but this is intentionally
deferred until after we fix up the LPI translation cache.

v2: https://lore.kernel.org/kvmarm/20240213093250.3960069-1-oliver.upton@linux.dev/

v2 -> v3:
- Fix the stupid lock imbalance once and for all (Dan)
- Drop the tracepoints / stats I used for debugging my own crap (Marc)

Oliver Upton (10):
KVM: arm64: vgic: Store LPIs in an xarray
KVM: arm64: vgic: Use xarray to find LPI in vgic_get_lpi()
KVM: arm64: vgic-v3: Iterate the xarray to find pending LPIs
KVM: arm64: vgic-its: Walk the LPI xarray in vgic_copy_lpi_list()
KVM: arm64: vgic: Get rid of the LPI linked-list
KVM: arm64: vgic: Use atomics to count LPIs
KVM: arm64: vgic: Free LPI vgic_irq structs in an RCU-safe manner
KVM: arm64: vgic: Rely on RCU protection in vgic_get_lpi()
KVM: arm64: vgic: Ensure the irq refcount is nonzero when taking a ref
KVM: arm64: vgic: Don't acquire the lpi_list_lock in vgic_put_irq()

arch/arm64/kvm/vgic/vgic-debug.c | 2 +-
arch/arm64/kvm/vgic/vgic-init.c | 4 ++-
arch/arm64/kvm/vgic/vgic-its.c | 53 +++++++++++++++++++-----------
arch/arm64/kvm/vgic/vgic-v3.c | 3 +-
arch/arm64/kvm/vgic/vgic.c | 56 ++++++++++----------------------
arch/arm64/kvm/vgic/vgic.h | 15 ++++++---
include/kvm/arm_vgic.h | 9 ++---
7 files changed, 73 insertions(+), 69 deletions(-)

base-commit: 6613476e225e090cc9aad49be7fa504e290dd33d
--
2.44.0.rc0.258.g7320e95886-goog