Mini-OS: add 9pfs frontend

Add a frontend for the 9pfs PV device. For now add only the code needed
to connect to the backend and the related disconnect functionality. The
9pfs protocol support will be added later.

Due to its nature (ability to access files) the whole code is guarded
by "#ifdef HAVE_LIBC".

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Samuel Thibault <samuel.thibault@ens-lyon.org>

diff --git a/9pfront.c b/9pfront.c
new file mode 100644 (file)
index 0000000..89ecb3a
--- /dev/null
+++ b/9pfront.c
@@ -0,0 +1,286 @@
+/*
+ * Minimal 9pfs PV frontend for Mini-OS.
+ * Copyright (c) 2023 Juergen Gross, SUSE Software Solution GmbH
+ */
+
+#include <mini-os/os.h>
+#include <mini-os/lib.h>
+#include <mini-os/events.h>
+#include <mini-os/gnttab.h>
+#include <mini-os/xenbus.h>
+#include <mini-os/xmalloc.h>
+#include <errno.h>
+#include <xen/io/9pfs.h>
+#include <mini-os/9pfront.h>
+
+#ifdef HAVE_LIBC
+struct dev_9pfs {
+    int id;
+    char nodename[20];
+    unsigned int dom;
+    char *backend;
+
+    char *tag;
+    const char *mnt;
+
+    struct xen_9pfs_data_intf *intf;
+    struct xen_9pfs_data data;
+    RING_IDX prod_pvt_out;
+    RING_IDX cons_pvt_in;
+
+    grant_ref_t ring_ref;
+    evtchn_port_t evtchn;
+    unsigned int ring_order;
+    xenbus_event_queue events;
+};
+
+#define DEFAULT_9PFS_RING_ORDER  4
+
+static unsigned int ftype_9pfs;
+
+static void intr_9pfs(evtchn_port_t port, struct pt_regs *regs, void *data)
+{
+}
+
+static int open_9pfs(struct mount_point *mnt, const char *pathname, int flags,
+                     mode_t mode)
+{
+    errno = ENOSYS;
+
+    return -1;
+}
+
+static void free_9pfront(struct dev_9pfs *dev)
+{
+    unsigned int i;
+
+    if ( dev->data.in && dev->intf )
+    {
+        for ( i = 0; i < (1 << dev->ring_order); i++ )
+            gnttab_end_access(dev->intf->ref[i]);
+        free_pages(dev->data.in, dev->ring_order);
+    }
+    unbind_evtchn(dev->evtchn);
+    gnttab_end_access(dev->ring_ref);
+    free_page(dev->intf);
+    free(dev->backend);
+    free(dev->tag);
+    free(dev);
+}
+
+void *init_9pfront(unsigned int id, const char *mnt)
+{
+    struct dev_9pfs *dev;
+    char *msg;
+    char *reason = "";
+    xenbus_transaction_t xbt;
+    int retry = 1;
+    char bepath[64] = { 0 };
+    XenbusState state;
+    unsigned int i;
+    void *addr;
+    char *version;
+    char *v;
+
+    printk("9pfsfront add %u, for mount at %s\n", id, mnt);
+    dev = malloc(sizeof(*dev));
+    memset(dev, 0, sizeof(*dev));
+    snprintf(dev->nodename, sizeof(dev->nodename), "device/9pfs/%u", id);
+    dev->id = id;
+
+    msg = xenbus_read_unsigned(XBT_NIL, dev->nodename, "backend-id", &dev->dom);
+    if ( msg )
+        goto err;
+    msg = xenbus_read_string(XBT_NIL, dev->nodename, "backend", &dev->backend);
+    if ( msg )
+        goto err;
+    msg = xenbus_read_string(XBT_NIL, dev->nodename, "tag", &dev->tag);
+    if ( msg )
+        goto err;
+
+    snprintf(bepath, sizeof(bepath), "%s/state", dev->backend);
+    free(xenbus_watch_path_token(XBT_NIL, bepath, bepath, &dev->events));
+    state = xenbus_read_integer(bepath);
+    while ( msg == NULL && state < XenbusStateInitWait )
+        msg = xenbus_wait_for_state_change(bepath, &state, &dev->events);
+    if ( msg || state != XenbusStateInitWait )
+    {
+        reason = "illegal backend state";
+        goto err;
+    }
+
+    msg = xenbus_read_unsigned(XBT_NIL, dev->backend, "max-ring-page-order",
+                               &dev->ring_order);
+    if ( msg )
+        goto err;
+    if ( dev->ring_order > DEFAULT_9PFS_RING_ORDER )
+        dev->ring_order = DEFAULT_9PFS_RING_ORDER;
+
+    msg = xenbus_read_string(XBT_NIL, dev->backend, "versions", &version);
+    if ( msg )
+        goto err;
+    for ( v = version; *v; v++ )
+    {
+        if ( strtoul(v, &v, 10) == 1 && (*v == ',' || *v == 0) )
+        {
+            v = NULL;
+            break;
+        }
+        if ( *v != ',' && *v != 0 )
+        {
+            reason = "backend published illegal version string";
+            free(version);
+            goto err;
+        }
+    }
+    free(version);
+    if ( v )
+    {
+        reason = "backend doesn't support version 1";
+        goto err;
+    }
+
+    dev->ring_ref = gnttab_alloc_and_grant((void **)&dev->intf);
+    memset(dev->intf, 0, PAGE_SIZE);
+    if ( evtchn_alloc_unbound(dev->dom, intr_9pfs, dev, &dev->evtchn) )
+    {
+        reason = "no event channel";
+        goto err;
+    }
+    dev->intf->ring_order = dev->ring_order;
+    dev->data.in = (void *)alloc_pages(dev->ring_order);
+    dev->data.out = dev->data.in + XEN_FLEX_RING_SIZE(dev->ring_order);
+    for ( i = 0; i < (1 << dev->ring_order); i++ )
+    {
+        addr = dev->data.in + i * PAGE_SIZE;
+        dev->intf->ref[i] = gnttab_grant_access(dev->dom, virt_to_mfn(addr), 0);
+    }
+
+    while ( retry )
+    {
+        msg = xenbus_transaction_start(&xbt);
+        if ( msg )
+        {
+            free(msg);
+            msg = NULL;
+            reason = "starting transaction";
+            goto err;
+        }
+
+        msg = xenbus_printf(xbt, dev->nodename, "version", "%u", 1);
+        if ( msg )
+            goto err_tr;
+        msg = xenbus_printf(xbt, dev->nodename, "num-rings", "%u", 1);
+        if ( msg )
+            goto err_tr;
+        msg = xenbus_printf(xbt, dev->nodename, "ring-ref0", "%u",
+                            dev->ring_ref);
+        if ( msg )
+            goto err_tr;
+        msg = xenbus_printf(xbt, dev->nodename, "event-channel-0", "%u",
+                            dev->evtchn);
+        if ( msg )
+            goto err_tr;
+        msg = xenbus_printf(xbt, dev->nodename, "state", "%u",
+                            XenbusStateInitialised);
+        if ( msg )
+            goto err_tr;
+
+        free(xenbus_transaction_end(xbt, 0, &retry));
+    }
+
+    state = xenbus_read_integer(bepath);
+    while ( msg == NULL && state < XenbusStateConnected )
+        msg = xenbus_wait_for_state_change(bepath, &state, &dev->events);
+    if ( msg || state != XenbusStateConnected )
+    {
+        reason = "illegal backend state";
+        goto err;
+    }
+
+    msg = xenbus_printf(XBT_NIL, dev->nodename, "state", "%u",
+                        XenbusStateConnected);
+    if ( msg )
+        goto err;
+
+    unmask_evtchn(dev->evtchn);
+
+    dev->mnt = mnt;
+    if ( mount(dev->mnt, dev, open_9pfs) )
+    {
+        reason = "mount failed";
+        goto err;
+    }
+
+    return dev;
+
+ err_tr:
+    free(xenbus_transaction_end(xbt, 1, &retry));
+
+ err:
+    if ( bepath[0] )
+        free(xenbus_unwatch_path_token(XBT_NIL, bepath, bepath));
+    if ( msg )
+        printk("9pfsfront add %u failed, error %s accessing Xenstore\n",
+               id, msg);
+    else
+        printk("9pfsfront add %u failed, %s\n", id, reason);
+    free_9pfront(dev);
+    free(msg);
+    return NULL;
+}
+
+void shutdown_9pfront(void *dev)
+{
+    struct dev_9pfs *dev9p = dev;
+    char bepath[64];
+    XenbusState state;
+    char *msg;
+    char *reason = "";
+
+    umount(dev9p->mnt);
+    snprintf(bepath, sizeof(bepath), "%s/state", dev9p->backend);
+
+    msg = xenbus_printf(XBT_NIL, dev9p->nodename, "state", "%u",
+                        XenbusStateClosing);
+    if ( msg )
+        goto err;
+
+    state = xenbus_read_integer(bepath);
+    while ( msg == NULL && state < XenbusStateClosing)
+        msg = xenbus_wait_for_state_change(bepath, &state, &dev9p->events);
+    if ( msg || state != XenbusStateClosing )
+    {
+        reason = "illegal backend state";
+        goto err;
+    }
+
+    msg = xenbus_printf(XBT_NIL, dev9p->nodename, "state", "%u",
+                        XenbusStateClosed);
+    if ( msg )
+        goto err;
+
+    free_9pfront(dev9p);
+
+    return;
+
+ err:
+    if ( msg )
+        printk("9pfsfront shutdown %u failed, error %s accessing Xenstore\n",
+               dev9p->id, msg);
+    else
+        printk("9pfsfront shutdown %u failed, %s\n", dev9p->id, reason);
+    free(msg);
+}
+
+static const struct file_ops ops_9pfs = {
+    .name = "9pfs",
+};
+
+__attribute__((constructor))
+static void initialize_9pfs(void)
+{
+    ftype_9pfs = alloc_file_type(&ops_9pfs);
+}
+
+#endif /* HAVE_LIBC */

diff --git a/Config.mk b/Config.mk
index 1a24b30eccd3a1c2cc7dd14017abae73860f6fc5..677e93df43faf306671cd401d47daba647e89cb9 100644 (file)
--- a/Config.mk
+++ b/Config.mk
@@ -187,6 +187,7 @@ CONFIG-n += CONFIG_QEMU_XS_ARGS
 CONFIG-n += CONFIG_TEST
 CONFIG-n += CONFIG_PCIFRONT
 CONFIG-n += CONFIG_TPMFRONT
+CONFIG-n += CONFIG_9PFRONT
 CONFIG-n += CONFIG_TPM_TIS
 CONFIG-n += CONFIG_TPMBACK
 CONFIG-n += CONFIG_BALLOON

diff --git a/Makefile b/Makefile
index 747c7c011e37f6e3610cf63b439d84b1da55da66..7ee181a2dda632afad318a5d62b63fbadbe6e620 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -39,6 +39,7 @@ SUBDIRS := lib
 src-$(CONFIG_BLKFRONT) += blkfront.c
 src-$(CONFIG_CONSFRONT) += consfront.c
 src-$(CONFIG_TPMFRONT) += tpmfront.c
+src-$(CONFIG_9PFRONT) += 9pfront.c
 src-$(CONFIG_TPM_TIS) += tpm_tis.c
 src-$(CONFIG_TPMBACK) += tpmback.c
 src-y += console.c

diff --git a/arch/x86/testbuild/all-no b/arch/x86/testbuild/all-no
index f79a10123c3454e9a172966934dcb80dcfed45dc..5b3e99ede5201c2c6463f43706b41bc5bad23235 100644 (file)
--- a/arch/x86/testbuild/all-no
+++ b/arch/x86/testbuild/all-no
@@ -12,6 +12,7 @@ CONFIG_NETFRONT = n
 CONFIG_FBFRONT = n
 CONFIG_KBDFRONT = n
 CONFIG_CONSFRONT = n
+CONFIG_9PFRONT = n
 CONFIG_XENBUS = n
 CONFIG_LIBXS = n
 CONFIG_LWIP = n

diff --git a/arch/x86/testbuild/all-yes b/arch/x86/testbuild/all-yes
index faa3af32c6f1186bca7f6f278e8d18fe4a97adcd..8ae489a4e7da7cdd58bb205e6bcb2264fb2775eb 100644 (file)
--- a/arch/x86/testbuild/all-yes
+++ b/arch/x86/testbuild/all-yes
@@ -12,6 +12,7 @@ CONFIG_NETFRONT = y
 CONFIG_FBFRONT = y
 CONFIG_KBDFRONT = y
 CONFIG_CONSFRONT = y
+CONFIG_9PFRONT = y
 CONFIG_XENBUS = y
 CONFIG_LIBXS = y
 CONFIG_BALLOON = y

diff --git a/arch/x86/testbuild/newxen-yes b/arch/x86/testbuild/newxen-yes
index dc83e67049f55fb6a47658816e56da2962e6734b..ee27a3288f309676e6cb2cf2cfc2661d2d228402 100644 (file)
--- a/arch/x86/testbuild/newxen-yes
+++ b/arch/x86/testbuild/newxen-yes
@@ -12,6 +12,7 @@ CONFIG_NETFRONT = y
 CONFIG_FBFRONT = y
 CONFIG_KBDFRONT = y
 CONFIG_CONSFRONT = y
+CONFIG_9PFRONT = y
 CONFIG_XENBUS = y
 CONFIG_LIBXS = y
 CONFIG_BALLOON = y

diff --git a/include/9pfront.h b/include/9pfront.h
new file mode 100644 (file)
index 0000000..722ec56
--- /dev/null
+++ b/include/9pfront.h
@@ -0,0 +1,7 @@
+#ifndef __9PFRONT_H__
+#define __9PFRONT_H__
+
+void *init_9pfront(unsigned int id, const char *mnt);
+void shutdown_9pfront(void *dev);
+
+#endif /* __9PFRONT_H__ */