console/win32: allocate shareable display surface

Introduce qemu_win32_map_alloc() and qemu_win32_map_free() to allocate
shared memory mapping. The handle can be used to share the mapping with
another process.

Teach qemu_create_displaysurface() to allocate shared memory. Following
patches will introduce other places for shared memory allocation.

Other patches for -display dbus will share the memory when possible with
the client, to avoid expensive memory copy between the processes.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20230606115658.677673-10-marcandre.lureau@redhat.com>

include/sysemu/os-win32.h

@@ -263,6 +263,9 @@ EXCEPTION_DISPOSITION
 win32_close_exception_handler(struct _EXCEPTION_RECORD*, void*,
                               struct _CONTEXT*, void*);
 
+void *qemu_win32_map_alloc(size_t size, HANDLE *h, Error **errp);
+void qemu_win32_map_free(void *ptr, HANDLE h, Error **errp);
+
 #ifdef __cplusplus
 }
 #endif

include/ui/console.h

@@ -143,6 +143,10 @@ typedef struct DisplaySurface {
     GLenum gltype;
     GLuint texture;
 #endif
+#ifdef WIN32
+    HANDLE handle;
+    uint32_t handle_offset;
+#endif
 } DisplaySurface;
 
 typedef struct QemuUIInfo {
@@ -329,6 +333,10 @@ DisplaySurface *qemu_create_displaysurface_from(int width, int height,
 DisplaySurface *qemu_create_displaysurface_pixman(pixman_image_t *image);
 DisplaySurface *qemu_create_placeholder_surface(int w, int h,
                                                 const char *msg);
+#ifdef WIN32
+void qemu_displaysurface_win32_set_handle(DisplaySurface *surface,
+                                          HANDLE h, uint32_t offset);
+#endif
 PixelFormat qemu_default_pixelformat(int bpp);
 
 DisplaySurface *qemu_create_displaysurface(int width, int height);

ui/console.c

@@ -1513,18 +1513,59 @@ static QemuConsole *new_console(DisplayState *ds, console_type_t console_type,
     return s;
 }
 
+#ifdef WIN32
+void qemu_displaysurface_win32_set_handle(DisplaySurface *surface,
+                                          HANDLE h, uint32_t offset)
+{
+    assert(!surface->handle);
+
+    surface->handle = h;
+    surface->handle_offset = offset;
+}
+
+static void
+win32_pixman_image_destroy(pixman_image_t *image, void *data)
+{
+    DisplaySurface *surface = data;
+
+    if (!surface->handle) {
+        return;
+    }
+
+    assert(surface->handle_offset == 0);
+
+    qemu_win32_map_free(
+        pixman_image_get_data(surface->image),
+        surface->handle,
+        &error_warn
+    );
+}
+#endif
+
 DisplaySurface *qemu_create_displaysurface(int width, int height)
 {
-    DisplaySurface *surface = g_new0(DisplaySurface, 1);
+    DisplaySurface *surface;
+    void *bits = NULL;
+#ifdef WIN32
+    HANDLE handle = NULL;
+#endif
 
-    trace_displaysurface_create(surface, width, height);
-    surface->format = PIXMAN_x8r8g8b8;
-    surface->image = pixman_image_create_bits(surface->format,
-                                              width, height,
-                                              NULL, width * 4);
-    assert(surface->image != NULL);
+    trace_displaysurface_create(width, height);
+
+#ifdef WIN32
+    bits = qemu_win32_map_alloc(width * height * 4, &handle, &error_abort);
+#endif
+
+    surface = qemu_create_displaysurface_from(
+        width, height,
+        PIXMAN_x8r8g8b8,
+        width * 4, bits
+    );
     surface->flags = QEMU_ALLOCATED_FLAG;
 
+#ifdef WIN32
+    qemu_displaysurface_win32_set_handle(surface, handle, 0);
+#endif
     return surface;
 }
 
@@ -1540,6 +1581,10 @@ DisplaySurface *qemu_create_displaysurface_from(int width, int height,
                                               width, height,
                                               (void *)data, linesize);
     assert(surface->image != NULL);
+#ifdef WIN32
+    pixman_image_set_destroy_function(surface->image,
+                                      win32_pixman_image_destroy, surface);
+#endif
 
     return surface;
 }

ui/qemu-pixman.c

@@ -6,6 +6,7 @@
 #include "qemu/osdep.h"
 #include "ui/console.h"
 #include "standard-headers/drm/drm_fourcc.h"
+#include "trace.h"
 
 PixelFormat qemu_pixelformat_from_pixman(pixman_format_code_t format)
 {

ui/trace-events

@@ -9,7 +9,7 @@ console_putchar_unhandled(int ch) "unhandled escape character '%c'"
 console_txt_new(int w, int h) "%dx%d"
 console_select(int nr) "%d"
 console_refresh(int interval) "interval %d ms"
-displaysurface_create(void *display_surface, int w, int h) "surface=%p, %dx%d"
+displaysurface_create(int w, int h) "%dx%d"
 displaysurface_create_from(void *display_surface, int w, int h, uint32_t format) "surface=%p, %dx%d, format 0x%x"
 displaysurface_create_pixman(void *display_surface) "surface=%p"
 displaysurface_free(void *display_surface) "surface=%p"

util/oslib-win32.c

@@ -835,3 +835,36 @@ int qemu_msync(void *addr, size_t length, int fd)
      */
     return qemu_fdatasync(fd);
 }
+
+void *qemu_win32_map_alloc(size_t size, HANDLE *h, Error **errp)
+{
+    void *bits;
+
+    trace_win32_map_alloc(size);
+
+    *h = CreateFileMapping(INVALID_HANDLE_VALUE, NULL, PAGE_READWRITE, 0,
+                          size, NULL);
+    if (*h == NULL) {
+        error_setg_win32(errp, GetLastError(), "Failed to CreateFileMapping");
+        return NULL;
+    }
+
+    bits = MapViewOfFile(*h, FILE_MAP_ALL_ACCESS, 0, 0, size);
+    if (bits == NULL) {
+        error_setg_win32(errp, GetLastError(), "Failed to MapViewOfFile");
+        CloseHandle(*h);
+        return NULL;
+    }
+
+    return bits;
+}
+
+void qemu_win32_map_free(void *ptr, HANDLE h, Error **errp)
+{
+    trace_win32_map_free(ptr, h);
+
+    if (UnmapViewOfFile(ptr) == 0) {
+        error_setg_win32(errp, GetLastError(), "Failed to UnmapViewOfFile");
+    }
+    CloseHandle(h);
+}

util/trace-events

@@ -52,6 +52,10 @@ qemu_anon_ram_alloc(size_t size, void *ptr) "size %zu ptr %p"
 qemu_vfree(void *ptr) "ptr %p"
 qemu_anon_ram_free(void *ptr, size_t size) "ptr %p size %zu"
 
+# oslib-win32.c
+win32_map_alloc(size_t size) "size:%zd"
+win32_map_free(void *ptr, void *h) "ptr:%p handle:%p"
+
 # hbitmap.c
 hbitmap_iter_skip_words(const void *hb, void *hbi, uint64_t pos, unsigned long cur) "hb %p hbi %p pos %"PRId64" cur 0x%lx"
 hbitmap_reset(void *hb, uint64_t start, uint64_t count, uint64_t sbit, uint64_t ebit) "hb %p items %"PRIu64",%"PRIu64" bits %"PRIu64"..%"PRIu64