[PULL 17/18] virtio-mem: don't warn about THP sizes on a kernel without THP support

["Michael S. Tsirkin" <mst@redhat.com>]

From: David Hildenbrand <david@redhat.com>

If the config directory in sysfs does not exist at all, we are dealing
with a system that does not support THPs. Simply use 1 MiB block size
then, instead of warning "Could not detect THP size, falling back to
..." and falling back to the default THP size.

Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Gavin Shan <gshan@redhat.com>
Cc: Juraj Marcin <jmarcin@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20240910163433.2100295-1-david@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 hw/virtio/virtio-mem.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/hw/virtio/virtio-mem.c b/hw/virtio/virtio-mem.c
index ef64bf1b4a..4075f3d4ce 100644
--- a/hw/virtio/virtio-mem.c
+++ b/hw/virtio/virtio-mem.c
@@ -88,6 +88,7 @@ static uint32_t virtio_mem_default_thp_size(void)
 static uint32_t thp_size;
 
 #define HPAGE_PMD_SIZE_PATH "/sys/kernel/mm/transparent_hugepage/hpage_pmd_size"
+#define HPAGE_PATH "/sys/kernel/mm/transparent_hugepage/"
 static uint32_t virtio_mem_thp_size(void)
 {
     gchar *content = NULL;
@@ -98,6 +99,12 @@ static uint32_t virtio_mem_thp_size(void)
         return thp_size;
     }
 
+    /* No THP -> no restrictions. */
+    if (!g_file_test(HPAGE_PATH, G_FILE_TEST_EXISTS)) {
+        thp_size = VIRTIO_MEM_MIN_BLOCK_SIZE;
+        return thp_size;
+    }
+
     /*
      * Try to probe the actual THP size, fallback to (sane but eventually
      * incorrect) default sizes.
-- 
MST