In case the guest doesn't have any LPI, we previously relied on the
iterator setting
'intid = nr_spis + VGIC_NR_PRIVATE_IRQS' && 'lpi_idx = 1'
to exit the iterator. But it was broken with commit 85d3ccc8b7 ("KVM:
arm64: vgic-debug: Use an xarray mark for debug iterator") -- the intid
remains at 'nr_spis + VGIC_NR_PRIVATE_IRQS - 1', and we end up endlessly
printing the last SPI's state.
Consider that it's meaningless to search the LPI xarray and populate
lpi_idx when there is no LPI, let's just skip the process for that case.
The result is that
* If there's no LPI, we focus on the intid and exit the iterator when it
runs out of the valid SPI range.
* Otherwise we keep the current logic and let the xarray drive the
iterator.
Fixes: 85d3ccc8b7 ("KVM: arm64: vgic-debug: Use an xarray mark for debug iterator")
Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20240807052024.2084-1-yuzenghui@huawei.com
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
The vgic debug iterator is the final user of vgic_copy_lpi_list(), but
is a bit more complicated to transition to something else. Use a mark
in the LPI xarray to record the indices 'known' to the debug iterator.
Protect against the LPIs from being freed by associating an additional
reference with the xarray mark.
Rework iter_next() to let the xarray walk 'drive' the iteration after
visiting all of the SGIs, PPIs, and SPIs.
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20240422200158.2606761-6-oliver.upton@linux.dev
Signed-off-by: Marc Zyngier <maz@kernel.org>
Almost all of the vgic state is VM-scoped but accessed from the context
of a vCPU. These accesses were serialized on the kvm->lock which cannot
be nested within a vcpu->mutex critical section.
Move over the vgic state to using the config_lock. Tweak the lock
ordering where necessary to ensure that the config_lock is acquired
after the vcpu->mutex. Acquire the config_lock in kvm_vgic_create() to
avoid a race between the converted flows and GIC creation. Where
necessary, continue to acquire kvm->lock to avoid a race with vCPU
creation (i.e. flows that use lock_all_vcpus()).
Finally, promote the locking expectations in comments to lockdep
assertions and update the locking documentation for the config_lock as
well as vcpu->mutex.
Cc: stable@vger.kernel.org
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230327164747.2466958-5-oliver.upton@linux.dev
