Commit 7816e589 authored by Christoph Schlameuss's avatar Christoph Schlameuss Committed by Janosch Frank
Browse files

kvm: s390: Reject memory region operations for ucontrol VMs 



This change rejects the KVM_SET_USER_MEMORY_REGION and
KVM_SET_USER_MEMORY_REGION2 ioctls when called on a ucontrol VM.
This is necessary 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.

Signed-off-by: default avatarChristoph Schlameuss <schlameuss@linux.ibm.com>
Fixes: 27e0393f ("KVM: s390: ucontrol: per vcpu address spaces")
Reviewed-by: default avatarClaudio Imbrenda <imbrenda@linux.ibm.com>
Link: https://lore.kernel.org/r/20240624095902.29375-1-schlameuss@linux.ibm.com


Signed-off-by: default avatarJanosch Frank <frankja@linux.ibm.com>
[frankja@linux.ibm.com: commit message spelling fix, subject prefix fix]
Message-ID: <20240624095902.29375-1-schlameuss@linux.ibm.com>
parent 33a729a1

Documentation/virt/kvm/api.rst

+12 −0
Original line number Diff line number Diff line
@@ -1403,6 +1403,12 @@ Instead, an abort (data abort if the cause of the page-table update 
was a load or a store, instruction abort if it was an instruction

fetch) is injected in the guest.



S390:

^^^^^



Returns -EINVAL if the VM has the KVM_VM_S390_UCONTROL flag set.

Returns -EINVAL if called on a protected VM.



4.36 KVM_SET_TSS_ADDR

---------------------
@@ -6273,6 +6279,12 @@ state. At VM creation time, all memory is shared, i.e. the PRIVATE attribute 
is '0' for all gfns.  Userspace can control whether memory is shared/private by

toggling KVM_MEMORY_ATTRIBUTE_PRIVATE via KVM_SET_MEMORY_ATTRIBUTES as needed.



S390:

^^^^^



Returns -EINVAL if the VM has the KVM_VM_S390_UCONTROL flag set.

Returns -EINVAL if called on a protected VM.



4.141 KVM_SET_MEMORY_ATTRIBUTES

-------------------------------

arch/s390/kvm/kvm-s390.c

+3 −0
Original line number Diff line number Diff line
@@ -5748,6 +5748,9 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm, 
{

	gpa_t size;



	if (kvm_is_ucontrol(kvm))

		return -EINVAL;



	/* When we are protected, we should not change the memory slots */

	if (kvm_s390_pv_get_handle(kvm))

		return -EINVAL;