Re: [PATCH v2 6/9] 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().
> 
> Signed-off-by: Claudio Imbrenda <[email protected]>

Sashiko has reviewed this patch and found no issues. It looks great!

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