linux-toradex.git/arch/s390/kvm, branch master

Merge tag 'kvm-s390-next-7.1-1' of https://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux into HEAD

2026-04-13T17:01:15+00:00

- ESA nesting support
- 4k memslots
- LPSW/E fix

KVM: s390: vsie: Fix races with partial gmap invalidations

2026-04-07T16:20:58+00:00

Introduce a new boolean flag, used for shadow gmaps, to keep track of
whether the gmap has been invalidated, either partially or totally.

Use the new flag to check whether shadow gmap invalidations happened
during shadowing. In such cases, abort whatever was going on, return
-EAGAIN and let the caller try again.

Fixes: 19d6c5b80443 ("KVM: s390: vsie: Fix unshadowing while shadowing")
Signed-off-by: Claudio Imbrenda 
Message-ID: <20260407161721.247044-1-imbrenda@linux.ibm.com>

KVM: s390: ucontrol: Fix memslot handling

2026-04-07T15:20:42+00:00

Fix memslots handling for UCONTROL guests. Attempts to delete user
memslots will fail, as they should, without the risk of a NULL pointer
dereference.

Fixes: 413c98f24c63 ("KVM: s390: fake memslot for ucontrol VMs")
Reviewed-by: Steffen Eiden 
Signed-off-by: Claudio Imbrenda

KVM: s390: Allow 4k granularity for memslots

2026-04-07T15:07:22+00:00

Until now memslots on s390 needed to have 1M granularity and be 1M
aligned. Since the new gmap code can handle memslots with 4k
granularity and alignment, remove the restrictions.

Reviewed-by: Christian Borntraeger 
Reviewed-by: Steffen Eiden 
Signed-off-by: Claudio Imbrenda

KVM: s390: Add alignment checks for hugepages

2026-04-07T15:07:19+00:00

When backing a guest page with a large page, check that the alignment
of the guest page matches the alignment of the host physical page
backing it within the large page.

Also check that the memslot is large enough to fit the large page.

Those checks are currently not needed, because memslots are guaranteed
to be 1m-aligned, but this will change.

Reviewed-by: Steffen Eiden 
Signed-off-by: Claudio Imbrenda

KVM: s390: Add some useful mask macros

2026-04-07T15:07:14+00:00

Add _{SEGMENT,REGION3}_FR_MASK, similar to _{SEGMENT,REGION3}_MASK, but
working on gfn/pfn instead of addresses. Use them in gaccess.c instead
of using the normal masks plus gpa_to_gfn().

Also add _PAGES_PER_{SEGMENT,REGION3} to make future code more readable.

Reviewed-by: Steffen Eiden 
Signed-off-by: Claudio Imbrenda

KVM: s390: Add KVM capability for ESA mode guests

2026-04-02T13:37:02+00:00

Now that all the bits are properly addressed, provide a mechanism
for testing ESA mode guests in nested configurations.

Signed-off-by: Hendrik Brueckner 
[farman@us.ibm.com: Updated commit message]
Reviewed-by: Janosch Frank 
Signed-off-by: Eric Farman 
Signed-off-by: Janosch Frank

KVM: s390: vsie: Accommodate ESA prefix pages

2026-04-02T13:37:01+00:00

The prefix page address occupies a different number
of bits for z/Architecture versus ESA mode. Adjust the
definition to cover both, and permit an ESA mode
address within the nested codepath.

Signed-off-by: Eric Farman 
Reviewed-by: Hendrik Brueckner 
Signed-off-by: Janosch Frank

KVM: s390: vsie: Disable some bits when in ESA mode

2026-04-02T13:37:01+00:00

In the event that a nested guest is put in ESA mode,
ensure that some bits are scrubbed from the shadow SCB.

Reviewed-by: Christian Borntraeger 
Signed-off-by: Eric Farman 
Reviewed-by: Hendrik Brueckner 
Signed-off-by: Janosch Frank

KVM: s390: vsie: Allow non-zarch guests

2026-04-02T13:37:01+00:00

Linux/KVM runs in z/Architecture-only mode. Although z/Architecture
is built upon a long history of hardware refinements, any other
CPU mode is not permitted.

Allow a userspace to explicitly enable the use of ESA mode for
nested guests, otherwise usage will be rejected.

Reviewed-by: Janosch Frank 
Signed-off-by: Eric Farman 
Reviewed-by: Hendrik Brueckner 
Reviewed-by: Christian Borntraeger 
Signed-off-by: Janosch Frank