diff options
| author | Ulrich Weigand <Ulrich.Weigand@de.ibm.com> | 2020-02-04 08:51:58 -0500 |
|---|---|---|
| committer | Christian Borntraeger <borntraeger@de.ibm.com> | 2020-02-27 19:47:10 +0100 |
| commit | f65470661f3648fe6d3d13475d01a744bb14f8b4 (patch) | |
| tree | 2407431e6ff7813b5c8e1c6e8948a666aff064f9 /Documentation/virt/kvm/devices/s390_flic.rst | |
| parent | f15587c83460e4be92f0a5d7ae73e26eab13254d (diff) | |
KVM: s390/interrupt: do not pin adapter interrupt pages
The adapter interrupt page containing the indicator bits is currently
pinned. That means that a guest with many devices can pin a lot of
memory pages in the host. This also complicates the reference tracking
which is needed for memory management handling of protected virtual
machines. It might also have some strange side effects for madvise
MADV_DONTNEED and other things.
We can simply try to get the userspace page set the bits and free the
page. By storing the userspace address in the irq routing entry instead
of the guest address we can actually avoid many lookups and list walks
so that this variant is very likely not slower.
If userspace messes around with the memory slots the worst thing that
can happen is that we write to some other memory within that process.
As we get the the page with FOLL_WRITE this can also not be used to
write to shared read-only pages.
Signed-off-by: Ulrich Weigand <Ulrich.Weigand@de.ibm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
[borntraeger@de.ibm.com: patch simplification]
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Diffstat (limited to 'Documentation/virt/kvm/devices/s390_flic.rst')
| -rw-r--r-- | Documentation/virt/kvm/devices/s390_flic.rst | 11 |
1 files changed, 2 insertions, 9 deletions
diff --git a/Documentation/virt/kvm/devices/s390_flic.rst b/Documentation/virt/kvm/devices/s390_flic.rst index 954190da7d04..ea96559ba501 100644 --- a/Documentation/virt/kvm/devices/s390_flic.rst +++ b/Documentation/virt/kvm/devices/s390_flic.rst @@ -108,16 +108,9 @@ Groups: mask or unmask the adapter, as specified in mask KVM_S390_IO_ADAPTER_MAP - perform a gmap translation for the guest address provided in addr, - pin a userspace page for the translated address and add it to the - list of mappings - - .. note:: A new mapping will be created unconditionally; therefore, - the calling code should avoid making duplicate mappings. - + This is now a no-op. The mapping is purely done by the irq route. KVM_S390_IO_ADAPTER_UNMAP - release a userspace page for the translated address specified in addr - from the list of mappings + This is now a no-op. The mapping is purely done by the irq route. KVM_DEV_FLIC_AISM modify the adapter-interruption-suppression mode for a given isc if the |