CVE-2026-98930

In the Linux kernel, the following vulnerability has been resolved:

KVM: s390: Fix IRQ injection with SIGP Stop and Store Status

When inject sigp stop() is called for a Stop and Store Status operation, if the vCPU is running, the interrupt is marked as pending and the status is stored by the thread performing the KVM RUN IOCTL.

If the vCPU is already stopped, the status is stored immediately.

Storing the status means writing into userspace, which might fault, and inject sigp stop() is called from do inject vcpu() which in turn is always called holding a spinlock, which is obviously an issue.

Fix this by returning -EWOULDBLOCK from inject sigp stop(), and adding a bool flag to indicate whether a store status is needed. The callers of do inject vcpu() are modified to pass the pointer to the bool flag; whenever a Store Status operation is needed, the callers can now perform it outside the spinlock.

Opportunistically refactor kvm s390 set irq state() to use scoped guard() and free().

[ Added Fixes tag while picking -- Claudio ]