[PATCH v2 1/1] target/s390x: Allow 2G hugepages guest backing

Allow mapping guest with 2G hugepages on hosts that support it.

Add new helper functions to check whether hpages are in effect, and
which size.

Signed-off-by: Claudio Imbrenda <[email protected]>
Reviewed-by: Eric Farman <[email protected]>
Reviewed-by: Hendrik Brueckner <[email protected]>
---
 target/s390x/diag.c          |  2 +-
 target/s390x/kvm/kvm.c       | 40 +++++++++++++++++++++++-------------
 target/s390x/kvm/kvm_s390x.h |  2 ++
 target/s390x/kvm/stubs.c     | 10 +++++++++
 4 files changed, 39 insertions(+), 15 deletions(-)

diff --git a/target/s390x/diag.c b/target/s390x/diag.c
index 80f0958478..46d191b87d 100644
--- a/target/s390x/diag.c
+++ b/target/s390x/diag.c
@@ -185,7 +185,7 @@ out:
             return false;
         }
 
-        if (kvm_enabled() && kvm_s390_get_hpage_1m()) {
+        if (kvm_enabled() && kvm_s390_get_hpage()) {
             error_report("Protected VMs can currently not be backed with "
                          "huge pages");
             env->regs[r1 + 1] = DIAG_308_RC_INVAL_FOR_PV;
diff --git a/target/s390x/kvm/kvm.c b/target/s390x/kvm/kvm.c
index 72031a5714..0d04e940ef 100644
--- a/target/s390x/kvm/kvm.c
+++ b/target/s390x/kvm/kvm.c
@@ -145,7 +145,7 @@ static int cap_mem_op;
 static int cap_mem_op_extension;
 static int cap_s390_irq;
 static int cap_ri;
-static int cap_hpage_1m;
+static int cap_hpage;
 static int cap_vcpu_resets;
 static int cap_protected;
 static int cap_zpci_op;
@@ -231,7 +231,7 @@ static void kvm_s390_enable_cmma(void)
         .attr = KVM_S390_VM_MEM_ENABLE_CMMA,
     };
 
-    if (cap_hpage_1m) {
+    if (cap_hpage) {
         warn_report("CMM will not be enabled because it is not "
                     "compatible with huge memory backings.");
         return;
@@ -298,24 +298,36 @@ void kvm_s390_set_max_pagesize(uint64_t pagesize, Error **errp)
         return;
     }
 
-    if (pagesize != 1 * MiB) {
-        error_setg(errp, "Memory backing with 2G pages was specified, "
-                   "but KVM does not support this memory backing");
-        return;
-    }
-
-    if (kvm_vm_enable_cap(kvm_state, KVM_CAP_S390_HPAGE_1M, 0)) {
-        error_setg(errp, "Memory backing with 1M pages was specified, "
-                   "but KVM does not support this memory backing");
-        return;
+    if (pagesize == 2 * GiB) {
+        if (kvm_vm_enable_cap(kvm_state, KVM_CAP_S390_HPAGE_2G, 0)) {
+            error_setg(errp, "Memory backing with 2G pages was specified, "
+                       "but KVM does not support this memory backing");
+            return;
+        }
+        cap_hpage = 2;
+    } else if (pagesize == MiB) {
+        if (kvm_vm_enable_cap(kvm_state, KVM_CAP_S390_HPAGE_1M, 0)) {
+            error_setg(errp, "Memory backing with 1M pages was specified, "
+                       "but KVM does not support this memory backing");
+            return;
+        }
+        cap_hpage = 1;
     }
+}
 
-    cap_hpage_1m = 1;
+int kvm_s390_get_hpage(void)
+{
+    return cap_hpage;
 }
 
 int kvm_s390_get_hpage_1m(void)
 {
-    return cap_hpage_1m;
+    return cap_hpage == 1;
+}
+
+int kvm_s390_get_hpage_2g(void)
+{
+    return cap_hpage == 2;
 }
 
 static void ccw_machine_class_foreach(ObjectClass *oc, void *opaque)
diff --git a/target/s390x/kvm/kvm_s390x.h b/target/s390x/kvm/kvm_s390x.h
index 7b1cce3e60..ccc615abed 100644
--- a/target/s390x/kvm/kvm_s390x.h
+++ b/target/s390x/kvm/kvm_s390x.h
@@ -25,7 +25,9 @@ void kvm_s390_program_interrupt(S390CPU *cpu, uint16_t code);
 int kvm_s390_set_cpu_state(S390CPU *cpu, uint8_t cpu_state);
 void kvm_s390_vcpu_interrupt_pre_save(S390CPU *cpu);
 int kvm_s390_vcpu_interrupt_post_load(S390CPU *cpu);
+int kvm_s390_get_hpage(void);
 int kvm_s390_get_hpage_1m(void);
+int kvm_s390_get_hpage_2g(void);
 int kvm_s390_get_protected_dump(void);
 int kvm_s390_get_ri(void);
 int kvm_s390_get_zpci_op(void);
diff --git a/target/s390x/kvm/stubs.c b/target/s390x/kvm/stubs.c
index 196127baa5..06e865f806 100644
--- a/target/s390x/kvm/stubs.c
+++ b/target/s390x/kvm/stubs.c
@@ -143,11 +143,21 @@ int kvm_s390_vcpu_interrupt_post_load(S390CPU *cpu)
     g_assert_not_reached();
 }
 
+int kvm_s390_get_hpage(void)
+{
+    g_assert_not_reached();
+}
+
 int kvm_s390_get_hpage_1m(void)
 {
     g_assert_not_reached();
 }
 
+int kvm_s390_get_hpage_2g(void)
+{
+    g_assert_not_reached();
+}
+
 void kvm_s390_enable_css_support(S390CPU *cpu)
 {
     g_assert_not_reached();
-- 
2.55.0