shinys000114/linux
1
0
Fork 0
mirror of https://github.com/hardkernel/linux.git synced 2026-06-05 02:21:52 +09:00
Code Issues Packages Projects Releases Wiki Activity

UPSTREAM: KVM: arm64: Ensure vgic_ready() is ordered against MMIO registration

Browse Source 
kvm_vgic_map_resources() prematurely marks the distributor as 'ready',
potentially allowing vCPUs to enter the guest before the distributor's
MMIO registration has been made visible.

Plug the race by marking the distributor as ready only after MMIO
registration is completed. Rely on the implied ordering of
synchronize_srcu() to ensure the MMIO registration is visible before
vgic_dist::ready. This also means that writers to vgic_dist::ready are
now serialized by the slots_lock, which was effectively the case already
as all writers held the slots_lock in addition to the config_lock.

Bug: 254441685
Fixes: 59112e9c39 ("KVM: arm64: vgic: Fix a circular locking issue")
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20241017001947.2707312-3-oliver.upton@linux.dev
Signed-off-by: Marc Zyngier <maz@kernel.org>
(cherry picked from commit 78a00555550042ed77b33ace7423aced228b3b4e)
Signed-off-by: Lee Jones <joneslee@google.com>
Change-Id: I01a7bdc92bbfe8642829c0c8f5e1bb55e1aea18f
This commit is contained in:
Oliver Upton
2024-10-17 00:19:47 +00:00
committed by Treehugger Robot
parent 34f1eb9985
commit 7c2011337f
1 changed files with 11 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

13
arch/arm64/kvm/vgic/vgic-init.c
View File

@@ -482,14 +482,23 @@ int kvm_vgic_map_resources(struct kvm *kvm)
if (ret)
goto out;
dist->ready = true;
dist_base = dist->vgic_dist_base;
mutex_unlock(&kvm->arch.config_lock);
ret = vgic_register_dist_iodev(kvm, dist_base, type);
if (ret)
if (ret) {
kvm_err("Unable to register VGIC dist MMIO regions\n");
goto out_slots;
}
/*
* kvm_io_bus_register_dev() guarantees all readers see the new MMIO
* registration before returning through synchronize_srcu(), which also
* implies a full memory barrier. As such, marking the distributor as
* 'ready' here is guaranteed to be ordered after all vCPUs having seen
* a completely configured distributor.
*/
dist->ready = true;
goto out_slots;
out:
mutex_unlock(&kvm->arch.config_lock);