linux-kernel - Re: [PATCH] s390/kvm: Reject memory region operations for ucontrol VMs

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Date: Thu, 27 Jun 2024 13:52:04 +0200
From: Janosch Frank <frankja@...ux.ibm.com>
To: Christoph Schlameuss <schlameuss@...ux.ibm.com>,
        linux-s390@...r.kernel.org
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Christian Borntraeger <borntraeger@...ux.ibm.com>,
        Claudio Imbrenda <imbrenda@...ux.ibm.com>,
        David Hildenbrand <david@...hat.com>,
        Paolo Bonzini <pbonzini@...hat.com>, Jonathan Corbet <corbet@....net>,
        linux-doc@...r.kernel.org
Subject: Re: [PATCH] s390/kvm: Reject memory region operations for ucontrol
 VMs

On 6/24/24 11:59, Christoph Schlameuss wrote:
> This change rejects the KVM_SET_USER_MEMORY_REGION and
> KVM_SET_USER_MEMORY_REGION2 ioctls when called on a ucontrol VM.
> This is neccessary since ucontrol VMs have kvm->arch.gmap set to 0 and
> would thus result in a null pointer dereference further in.
> Memory management needs to be performed in userspace and using the
> ioctls KVM_S390_UCAS_MAP and KVM_S390_UCAS_UNMAP.
> 
> Also improve s390 specific documentation for KVM_SET_USER_MEMORY_REGION
> and KVM_SET_USER_MEMORY_REGION2.
> 

I'll add this tag when picking since it's a fix:
Fixes: 27e0393f15fc ("KVM: s390: ucontrol: per vcpu address spaces")

It's a bit hard to track down the commit that should have contained your 
code to begin with and I think this is the closest we'll get.