accel/tcg: Use interval tree for user-only page tracking

Finish weaning user-only away from PageDesc.

Using an interval tree to track page permissions means that
we can represent very large regions efficiently.

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/290
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/967
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1214
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

1 files changed, 22 insertions, 0 deletions

diff --git a/tests/tcg/multiarch/test-vma.c b/tests/tcg/multiarch/test-vma.c
new file mode 100644
index 0000000000..2893d60334
--- /dev/null
+++ b/tests/tcg/multiarch/test-vma.c
@@ -0,0 +1,22 @@
+/*
+ * Test very large vma allocations.
+ * The qemu out-of-memory condition was within the mmap syscall itself.
+ * If the syscall actually returns with MAP_FAILED, the test succeeded.
+ */
+#include <sys/mman.h>
+
+int main()
+{
+    int n = sizeof(size_t) == 4 ? 32 : 45;
+
+    for (int i = 28; i < n; i++) {
+        size_t l = (size_t)1 << i;
+        void *p = mmap(0, l, PROT_NONE,
+                       MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE, -1, 0);
+        if (p == MAP_FAILED) {
+            break;
+        }
+        munmap(p, l);
+    }
+    return 0;
+}