exec: Introduce qemu_maxrampagesize() and rename qemu_getrampagesize()

Rename qemu_getrampagesize() to qemu_minrampagesize(). While at it,
properly rename find_max_supported_pagesize() to
find_min_backend_pagesize().

s390x is actually interested into the maximum ram pagesize, so
introduce and use qemu_maxrampagesize().

Add a TODO, indicating that looking at any mapped memory backends is not
100% correct in some cases.

Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20190417113143.5551-3-david@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>

exec.c

@@ -1688,7 +1688,7 @@ void ram_block_dump(Monitor *mon)
  * when we actually open and map them.  Iterate over the file
  * descriptors instead, and use qemu_fd_getpagesize().
  */
-static int find_max_supported_pagesize(Object *obj, void *opaque)
+static int find_min_backend_pagesize(Object *obj, void *opaque)
 {
     long *hpsize_min = opaque;
 
@@ -1704,7 +1704,27 @@ static int find_max_supported_pagesize(Object *obj, void *opaque)
     return 0;
 }
 
-long qemu_getrampagesize(void)
+static int find_max_backend_pagesize(Object *obj, void *opaque)
+{
+    long *hpsize_max = opaque;
+
+    if (object_dynamic_cast(obj, TYPE_MEMORY_BACKEND)) {
+        HostMemoryBackend *backend = MEMORY_BACKEND(obj);
+        long hpsize = host_memory_backend_pagesize(backend);
+
+        if (host_memory_backend_is_mapped(backend) && (hpsize > *hpsize_max)) {
+            *hpsize_max = hpsize;
+        }
+    }
+
+    return 0;
+}
+
+/*
+ * TODO: We assume right now that all mapped host memory backends are
+ * used as RAM, however some might be used for different purposes.
+ */
+long qemu_minrampagesize(void)
 {
     long hpsize = LONG_MAX;
     long mainrampagesize;
@@ -1724,7 +1744,7 @@ long qemu_getrampagesize(void)
      */
     memdev_root = object_resolve_path("/objects", NULL);
     if (memdev_root) {
-        object_child_foreach(memdev_root, find_max_supported_pagesize, &hpsize);
+        object_child_foreach(memdev_root, find_min_backend_pagesize, &hpsize);
     }
     if (hpsize == LONG_MAX) {
         /* No additional memory regions found ==> Report main RAM page size */
@@ -1747,8 +1767,24 @@ long qemu_getrampagesize(void)
 
     return hpsize;
 }
+
+long qemu_maxrampagesize(void)
+{
+    long pagesize = qemu_mempath_getpagesize(mem_path);
+    Object *memdev_root = object_resolve_path("/objects", NULL);
+
+    if (memdev_root) {
+        object_child_foreach(memdev_root, find_max_backend_pagesize,
+                             &pagesize);
+    }
+    return pagesize;
+}
 #else
-long qemu_getrampagesize(void)
+long qemu_minrampagesize(void)
+{
+    return getpagesize();
+}
+long qemu_maxrampagesize(void)
 {
     return getpagesize();
 }

hw/ppc/spapr_caps.c

@@ -347,7 +347,7 @@ static void cap_hpt_maxpagesize_apply(SpaprMachineState *spapr,
         warn_report("Many guests require at least 64kiB hpt-max-page-size");
     }
 
-    spapr_check_pagesize(spapr, qemu_getrampagesize(), errp);
+    spapr_check_pagesize(spapr, qemu_minrampagesize(), errp);
 }
 
 static bool spapr_pagesize_cb(void *opaque, uint32_t seg_pshift,
@@ -609,7 +609,7 @@ static SpaprCapabilities default_caps_with_cpu(SpaprMachineState *spapr,
         uint8_t mps;
 
         if (kvmppc_hpt_needs_host_contiguous_pages()) {
-            mps = ctz64(qemu_getrampagesize());
+            mps = ctz64(qemu_minrampagesize());
         } else {
             mps = 34; /* allow everything up to 16GiB, i.e. everything */
         }

hw/s390x/s390-virtio-ccw.c

@@ -188,7 +188,7 @@ static void s390_memory_init(ram_addr_t mem_size)
      * Configure the maximum page size. As no memory devices were created
      * yet, this is the page size of initial memory only.
      */
-    s390_set_max_pagesize(qemu_getrampagesize(), &local_err);
+    s390_set_max_pagesize(qemu_maxrampagesize(), &local_err);
     if (local_err) {
         error_report_err(local_err);
         exit(EXIT_FAILURE);

hw/vfio/spapr.c

@@ -148,7 +148,7 @@ int vfio_spapr_create_window(VFIOContainer *container,
     uint64_t pagesize = memory_region_iommu_get_min_page_size(iommu_mr);
     unsigned entries, bits_total, bits_per_level, max_levels;
     struct vfio_iommu_spapr_tce_create create = { .argsz = sizeof(create) };
-    long rampagesize = qemu_getrampagesize();
+    long rampagesize = qemu_minrampagesize();
 
     /*
      * The host might not support the guest supported IOMMU page size,

include/exec/ram_addr.h

@@ -73,7 +73,8 @@ static inline unsigned long int ramblock_recv_bitmap_offset(void *host_addr,
 
 bool ramblock_is_pmem(RAMBlock *rb);
 
-long qemu_getrampagesize(void);
+long qemu_minrampagesize(void);
+long qemu_maxrampagesize(void);
 
 /**
  * qemu_ram_alloc_from_file,

target/ppc/kvm.c

@@ -2136,7 +2136,7 @@ uint64_t kvmppc_rma_size(uint64_t current_size, unsigned int hash_shift)
     /* Find the largest hardware supported page size that's less than
      * or equal to the (logical) backing page size of guest RAM */
     kvm_get_smmu_info(&info, &error_fatal);
-    rampagesize = qemu_getrampagesize();
+    rampagesize = qemu_minrampagesize();
     best_page_shift = 0;
 
     for (i = 0; i < KVM_PPC_PAGE_SIZES_MAX_SZ; i++) {