[Xen-devel] [PATCH] Add tapdisk-ioemu tool

[Kevin Wolf <kwolf@xxxxxxx>]

Currently, tap:ioemu can only be used for domains which have a device
model running. This isn't the case for all domains. The most important
of the missing domains is Dom0 which needs acces e.g. to extract the
kernel from the domain's image.

tapdisk-ioemu is a tool compiled from ioemu source plus a small wrapper
which handles tap:ioemu access for domains without device model
(currently Dom0). You must start tapdisk-ioemu manually before trying to
attach a tap:ioemu disk to Dom0 at the moment. A patch to blktapctrl
will follow to automatically start tapdisk-ioemu when needed.

Signed-off-by: Kevin Wolf <kwolf@xxxxxxx>

diff -r ed6bd8daa82b tools/ioemu/Makefile
--- a/tools/ioemu/Makefile      Tue Apr  1 13:52:44 2008
+++ b/tools/ioemu/Makefile      Tue Apr  8 12:16:55 2008
@@ -16,6 +16,10 @@
 BASE_CFLAGS += -mcpu=ultrasparc
 endif
 CPPFLAGS += -I. -D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE
+CPPFLAGS += -I$(XEN_ROOT)/tools/libxc
+CPPFLAGS += -I$(XEN_ROOT)/tools/blktap/lib
+CPPFLAGS += -I$(XEN_ROOT)/tools/xenstore
+CPPFLAGS += -I$(XEN_ROOT)/tools/include
 LIBS=
 TOOLS=qemu-img$(EXESUF)
 ifdef CONFIG_STATIC
@@ -35,7 +39,7 @@
 endif
 endif
 
-TOOLS=
+TOOLS=tapdisk-ioemu
 
 all: $(TOOLS) $(DOCS) recurse-all
 
@@ -43,6 +47,9 @@
        $(MAKE) -C $(subst subdir-,,$@) all
 
 recurse-all: $(patsubst %,subdir-%, $(TARGET_DIRS))
+
+tapdisk-ioemu: tapdisk-ioemu.c cutils.c block.c block-raw.c block-cow.c 
block-qcow.c aes.c block-vmdk.c block-cloop.c block-dmg.c block-bochs.c 
block-vpc.c block-vvfat.c block-qcow2.c hw/xen_blktap.c
+       $(CC) -DQEMU_TOOL $(CFLAGS) $(CPPFLAGS) $(BASE_CFLAGS) $(LDFLAGS) 
$(BASE_LDFLAGS) -o $@ $^ -lz $(LIBS)
 
 qemu-img$(EXESUF): qemu-img.c cutils.c block.c block-raw.c block-cow.c 
block-qcow.c aes.c block-vmdk.c block-cloop.c block-dmg.c block-bochs.c 
block-vpc.c block-vvfat.c block-qcow2.c
        $(CC) -DQEMU_TOOL $(CFLAGS) $(CPPFLAGS) $(BASE_CFLAGS) $(LDFLAGS) 
$(BASE_LDFLAGS) -o $@ $^ -lz $(LIBS)
@@ -80,7 +87,7 @@
 
 install: all $(if $(BUILD_DOCS),install-doc)
        mkdir -p "$(DESTDIR)$(bindir)"
-#      $(INSTALL) -m 755 -s $(TOOLS) "$(DESTDIR)$(bindir)"
+       $(INSTALL) -m 755 -s $(TOOLS) "$(DESTDIR)$(prefix)/sbin"
 #      mkdir -p "$(DESTDIR)$(datadir)"
 #      for x in bios.bin vgabios.bin vgabios-cirrus.bin ppc_rom.bin \
 #              video.x openbios-sparc32 linux_boot.bin pxe-ne2k_pci.bin \
diff -r ed6bd8daa82b tools/ioemu/cutils.c
--- a/tools/ioemu/cutils.c      Tue Apr  1 13:52:44 2008
+++ b/tools/ioemu/cutils.c      Tue Apr  8 12:16:55 2008
@@ -81,3 +81,38 @@
         *ptr = p;
     return 1;
 }
+
+void *get_mmap_addr(unsigned long size)
+{
+    return NULL;
+}
+
+void qemu_free(void *ptr)
+{
+    free(ptr);
+}
+
+void *qemu_malloc(size_t size)
+{
+    return malloc(size);
+}
+
+void *qemu_mallocz(size_t size)
+{
+    void *ptr;
+    ptr = qemu_malloc(size);
+    if (!ptr)
+        return NULL;
+    memset(ptr, 0, size);
+    return ptr;
+}
+
+char *qemu_strdup(const char *str)
+{
+    char *ptr;
+    ptr = qemu_malloc(strlen(str) + 1);
+    if (!ptr)
+        return NULL;
+    strcpy(ptr, str);
+    return ptr;
+}
diff -r ed6bd8daa82b tools/ioemu/osdep.c
--- a/tools/ioemu/osdep.c       Tue Apr  1 13:52:44 2008
+++ b/tools/ioemu/osdep.c       Tue Apr  8 12:16:55 2008
@@ -44,21 +44,6 @@
 #else
 #include <malloc.h>
 #endif
-
-void *get_mmap_addr(unsigned long size)
-{
-    return NULL;
-}
-
-void qemu_free(void *ptr)
-{
-    free(ptr);
-}
-
-void *qemu_malloc(size_t size)
-{
-    return malloc(size);
-}
 
 #if defined(_WIN32)
 void *qemu_memalign(size_t alignment, size_t size)
@@ -216,23 +201,3 @@
 }
 
 #endif
-
-void *qemu_mallocz(size_t size)
-{
-    void *ptr;
-    ptr = qemu_malloc(size);
-    if (!ptr)
-        return NULL;
-    memset(ptr, 0, size);
-    return ptr;
-}
-
-char *qemu_strdup(const char *str)
-{
-    char *ptr;
-    ptr = qemu_malloc(strlen(str) + 1);
-    if (!ptr)
-        return NULL;
-    strcpy(ptr, str);
-    return ptr;
-}
diff -r ed6bd8daa82b tools/ioemu/vl.h
--- a/tools/ioemu/vl.h  Tue Apr  1 13:52:44 2008
+++ b/tools/ioemu/vl.h  Tue Apr  8 12:16:55 2008
@@ -159,7 +159,7 @@
 extern FILE *logfile;
 
 
-#if defined(__i386__) || defined(__x86_64__)
+#if (defined(__i386__) || defined(__x86_64__)) && !defined(QEMU_TOOL)
 #define MAPCACHE
 uint8_t *qemu_map_cache(target_phys_addr_t phys_addr);
 void     qemu_invalidate_map_cache(void);
@@ -1552,7 +1552,9 @@
 void timeoffset_get(void);
 
 /* xen_platform.c */
+#ifndef QEMU_TOOL
 void pci_xen_platform_init(PCIBus *bus);
+#endif
 
 
 void kqemu_record_dump(void);
diff -r ed6bd8daa82b tools/ioemu/tapdisk-ioemu.c
--- /dev/null   Tue Apr  1 13:52:44 2008
+++ b/tools/ioemu/tapdisk-ioemu.c       Tue Apr  8 12:16:55 2008
@@ -0,0 +1,141 @@
+#include <stdlib.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdint.h>
+#include <signal.h>
+
+#include <assert.h>
+
+extern int init_blktap(void);
+extern void qemu_aio_init(void);
+extern void qemu_aio_poll(void);
+extern void bdrv_init(void);
+
+extern void *qemu_mallocz(size_t size);
+extern void qemu_free(void *ptr);
+
+int domid = 0;
+FILE* logfile;
+
+void term_printf(const char *fmt, ...)
+{
+    va_list ap;
+    va_start(ap, fmt);
+    vprintf(fmt, ap);
+    va_end(ap);
+}
+
+void term_print_filename(const char *filename)
+{
+    term_printf(filename);
+}
+
+
+typedef void IOReadHandler(void *opaque, const uint8_t *buf, int size);
+typedef int IOCanRWHandler(void *opaque);
+typedef void IOHandler(void *opaque);
+
+typedef struct IOHandlerRecord {
+    int fd;
+    IOCanRWHandler *fd_read_poll;
+    IOHandler *fd_read;
+    IOHandler *fd_write;
+    int deleted;
+    void *opaque;
+    /* temporary data */
+    struct pollfd *ufd;
+    struct IOHandlerRecord *next;
+} IOHandlerRecord;
+
+static IOHandlerRecord *first_io_handler;
+
+int qemu_set_fd_handler2(int fd, 
+                         IOCanRWHandler *fd_read_poll, 
+                         IOHandler *fd_read, 
+                         IOHandler *fd_write, 
+                         void *opaque)
+{
+    IOHandlerRecord *ioh;
+
+    /* This is a stripped down version of fd handling */
+    assert(fd_read_poll == NULL);
+    assert(fd_write == NULL);
+
+    for(ioh = first_io_handler; ioh != NULL; ioh = ioh->next)
+        if (ioh->fd == fd)
+            goto found;
+    
+    if (!fd_read && !fd_write)
+        return 0;
+        
+    ioh = qemu_mallocz(sizeof(IOHandlerRecord));
+    if (!ioh)
+        return -1;
+    ioh->next = first_io_handler;
+    first_io_handler = ioh;
+
+found:
+    if (!fd_read && !fd_write) {
+        ioh->deleted = 1;
+    } else {
+        ioh->fd = fd;
+        ioh->fd_read = fd_read;
+        ioh->opaque = opaque;
+        ioh->deleted = 0;
+    }
+
+    return 0;
+}
+
+int main(void) 
+{
+    IOHandlerRecord *ioh, **pioh;
+    int max_fd;
+    fd_set rfds;
+    struct timeval tv;
+
+    logfile = stderr;
+    
+    bdrv_init();
+    qemu_aio_init();
+    init_blktap();
+   
+    /* 
+     * Main loop: Pass events to the corrsponding handlers and check for
+     * completed aio operations.
+     */
+    while (1) {
+        qemu_aio_poll();
+
+        max_fd = -1;
+        FD_ZERO(&rfds);
+        for(ioh = first_io_handler; ioh != NULL; ioh = ioh->next)
+            if (!ioh->deleted) {
+                FD_SET(ioh->fd, &rfds);
+                max_fd = max_fd > ioh->fd ? max_fd : ioh->fd;
+            }
+
+        tv.tv_sec = 0;
+        tv.tv_usec = 10000;
+        if (select(max_fd + 1, &rfds, NULL, NULL, &tv) <= 0)
+            continue;
+            
+        /* Call handlers */
+        for(ioh = first_io_handler; ioh != NULL; ioh = ioh->next)
+            if (FD_ISSET(ioh->fd, &rfds))
+                ioh->fd_read(ioh->opaque);
+
+        /* Remove deleted IO handlers */
+        pioh = &first_io_handler;
+        while (*pioh) {
+            ioh = *pioh;
+            if (ioh->deleted) {
+                *pioh = ioh->next;
+                qemu_free(ioh);
+            } else 
+                pioh = &ioh->next;
+        }
+    }
+    return 0;
+}

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