[Xen-devel] [PATCH v2 0/4] xen/arm: fix rank/vgic lock inversion bug

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

Hi all,

this patch series fixes a lock inversion bug in Xen on ARM. The locking
order is: first rank lock, then vgic lock. The order is respected
everywhere, except for gic_update_one_lr.

gic_update_one_lr is called with the vgic lock held, but it calls
vgic_get_target_vcpu, which tries to obtain the rank lock. This can
cause deadlocks.

The series fixes the issue by avoiding the rank lock in
gic_update_one_lr. It makes it safe by ensuring that the right vgic lock
is always taken by vgic_migrate_irq.

The first patch is just a fix to a bug I discovered while testing this
series.


Stefano Stabellini (4):
      xen/arm: fix GIC_INVALID_LR
      arm: store vcpu id in struct irq_pending
      arm,vgic_migrate_irq: take the right vgic lock
      The locking order is: first rank lock, then vgic lock. The order is     
respected everywhere, except for gic_update_one_lr.

 xen/arch/arm/gic.c         | 14 ++++++++++--
 xen/arch/arm/vgic-v2.c     | 12 +++-------
 xen/arch/arm/vgic-v3.c     |  6 +----
 xen/arch/arm/vgic.c        | 56 +++++++++++++++++++++++++++++++++++++---------
 xen/include/asm-arm/vgic.h |  8 +++++--
 5 files changed, 68 insertions(+), 28 deletions(-)

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
https://lists.xen.org/xen-devel