mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2025-12-27 13:30:45 -05:00
cd4178d194
When unmapping a vLPI, WARN if nullifying vCPU affinity fails, not just if
failure occurs when freeing an ITE. If undoing vCPU affinity fails, then
odds are very good that vLPI state tracking has has gotten out of whack,
i.e. that KVM and the GIC disagree on the state of an IRQ/vLPI. At best,
inconsistent state means there is a lurking bug/flaw somewhere. At worst,
the inconsistency could eventually be fatal to the host, e.g. if an ITS
command fails because KVM's view of things doesn't match reality/hardware.
Note, only the call from kvm_arch_irq_bypass_del_producer() by way of
kvm_vgic_v4_unset_forwarding() doesn't already WARN. Common KVM's
kvm_irq_routing_update() WARNs if kvm_arch_update_irqfd_routing() fails.
For that path, if its_unmap_vlpi() fails in kvm_vgic_v4_unset_forwarding(),
the only possible causes are that the GIC doesn't have a v4 ITS (from
its_irq_set_vcpu_affinity()):
/* Need a v4 ITS */
if (!is_v4(its_dev->its))
return -EINVAL;
guard(raw_spinlock)(&its_dev->event_map.vlpi_lock);
/* Unmap request? */
if (!info)
return its_vlpi_unmap(d);
or that KVM has gotten out of sync with the GIC/ITS (from its_vlpi_unmap()):
if (!its_dev->event_map.vm || !irqd_is_forwarded_to_vcpu(d))
return -EINVAL;
All of the above failure scenarios are warnable offences, as they should
never occur absent a kernel/KVM bug.
Acked-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/all/aFWY2LTVIxz5rfhh@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.