KVM: s390: Document the KVM_CAP_S390_HPAGE_2G capability

Document the KVM_CAP_S390_HPAGE_2G capability, which behaves very
similarly to the existing KVM_CAP_S390_HPAGE_1M.

Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Message-ID: <20260609150930.665370-5-imbrenda@linux.ibm.com>

diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index e7998feaa940b735d1eb164c5d1c634a4ac2377d..dfde0bfcbce612785dfcd9b1ef6ef0768a0dc2b6 100644 (file)
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -8905,6 +8905,21 @@ helpful if user space wants to emulate instructions which are not
 This capability can be enabled dynamically even if VCPUs were already
 created and are running.
 
+7.47 KVM_CAP_S390_HPAGE_2G
+--------------------------
+
+:Architectures: s390
+:Parameters: none
+:Returns: 0 on success; -EINVAL if hpage_2g module parameter was not set,
+          cmma is enabled, or the VM has the KVM_VM_S390_UCONTROL
+          flag set; -EBUSY if vCPUs were already created for the VM.
+
+With this capability the KVM support for memory backing with 2g pages
+through hugetlbfs can be enabled for a VM. After the capability is
+enabled, cmma can't be enabled anymore and pfmfi and the storage key
+interpretation are disabled. If cmma has already been enabled or the
+hpage_2g module parameter is not set to 1, -EINVAL is returned.
+
 8. Other capabilities.
 ======================