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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH 2/3] libxc: add xc_gntshr_* functions
These functions and the xc_gntshr device (/dev/xen/gntalloc on linux)
allow applications to create pages shared with other domains.
Signed-off-by: Daniel De Graaf <dgdegra@xxxxxxxxxxxxx>
---
tools/include/xen-sys/Linux/gntalloc.h | 82 +++++++++++++++++++++++++
tools/libxc/xc_gnttab.c | 27 ++++++++
tools/libxc/xc_linux_osdep.c | 102 ++++++++++++++++++++++++++++++++
tools/libxc/xc_private.c | 13 ++++
tools/libxc/xenctrl.h | 48 +++++++++++++++
tools/libxc/xenctrlosdep.h | 10 +++
6 files changed, 282 insertions(+), 0 deletions(-)
create mode 100644 tools/include/xen-sys/Linux/gntalloc.h
diff --git a/tools/include/xen-sys/Linux/gntalloc.h
b/tools/include/xen-sys/Linux/gntalloc.h
new file mode 100644
index 0000000..76bd580
--- /dev/null
+++ b/tools/include/xen-sys/Linux/gntalloc.h
@@ -0,0 +1,82 @@
+/******************************************************************************
+ * gntalloc.h
+ *
+ * Interface to /dev/xen/gntalloc.
+ *
+ * Author: Daniel De Graaf <dgdegra@xxxxxxxxxxxxx>
+ *
+ * This file is in the public domain.
+ */
+
+#ifndef __LINUX_PUBLIC_GNTALLOC_H__
+#define __LINUX_PUBLIC_GNTALLOC_H__
+
+/*
+ * Allocates a new page and creates a new grant reference.
+ */
+#define IOCTL_GNTALLOC_ALLOC_GREF \
+_IOC(_IOC_NONE, 'G', 5, sizeof(struct ioctl_gntalloc_alloc_gref))
+struct ioctl_gntalloc_alloc_gref {
+ /* IN parameters */
+ /* The ID of the domain to be given access to the grants. */
+ uint16_t domid;
+ /* Flags for this mapping */
+ uint16_t flags;
+ /* Number of pages to map */
+ uint32_t count;
+ /* OUT parameters */
+ /* The offset to be used on a subsequent call to mmap(). */
+ uint64_t index;
+ /* The grant references of the newly created grant, one per page */
+ /* Variable size, depending on count */
+ uint32_t gref_ids[1];
+};
+
+#define GNTALLOC_FLAG_WRITABLE 1
+
+/*
+ * Deallocates the grant reference, allowing the associated page to be freed if
+ * no other domains are using it.
+ */
+#define IOCTL_GNTALLOC_DEALLOC_GREF \
+_IOC(_IOC_NONE, 'G', 6, sizeof(struct ioctl_gntalloc_dealloc_gref))
+struct ioctl_gntalloc_dealloc_gref {
+ /* IN parameters */
+ /* The offset returned in the map operation */
+ uint64_t index;
+ /* Number of references to unmap */
+ uint32_t count;
+};
+
+/*
+ * Sets up an unmap notification within the page, so that the other side can do
+ * cleanup if this side crashes. Required to implement cross-domain robust
+ * mutexes or close notification on communication channels.
+ *
+ * Each mapped page only supports one notification; multiple calls referring to
+ * the same page overwrite the previous notification. You must clear the
+ * notification prior to the IOCTL_GNTALLOC_DEALLOC_GREF if you do not want it
+ * to occur.
+ */
+#define IOCTL_GNTALLOC_SET_UNMAP_NOTIFY \
+_IOC(_IOC_NONE, 'G', 7, sizeof(struct ioctl_gntalloc_unmap_notify))
+struct ioctl_gntalloc_unmap_notify {
+ /* IN parameters */
+ /* Offset in the file descriptor for a byte within the page (same as
+ * used in mmap). If using UNMAP_NOTIFY_CLEAR_BYTE, this is the byte to
+ * be cleared. Otherwise, it can be any byte in the page whose
+ * notification we are adjusting.
+ */
+ uint64_t index;
+ /* Action(s) to take on unmap */
+ uint32_t action;
+ /* Event channel to notify */
+ uint32_t event_channel_port;
+};
+
+/* Clear (set to zero) the byte specified by index */
+#define UNMAP_NOTIFY_CLEAR_BYTE 0x1
+/* Send an interrupt on the indicated event channel */
+#define UNMAP_NOTIFY_SEND_EVENT 0x2
+
+#endif /* __LINUX_PUBLIC_GNTALLOC_H__ */
diff --git a/tools/libxc/xc_gnttab.c b/tools/libxc/xc_gnttab.c
index 033cc5c..cb5995f 100644
--- a/tools/libxc/xc_gnttab.c
+++ b/tools/libxc/xc_gnttab.c
@@ -203,6 +203,33 @@ int xc_gnttab_set_max_grants(xc_gnttab *xcg, uint32_t
count)
return xcg->ops->u.gnttab.set_max_grants(xcg, xcg->ops_handle, count);
}
+void *xc_gntshr_share_pages(xc_gntshr *xcg, uint32_t domid,
+ int count, uint32_t *refs, int writable)
+{
+ return xcg->ops->u.gntshr.share_pages(xcg, xcg->ops_handle, domid,
+ count, refs, writable, -1, -1);
+}
+
+void *xc_gntshr_share_page_notify(xc_gntshr *xcg, uint32_t domid,
+ uint32_t *ref, int writable,
+ uint32_t notify_offset,
+ evtchn_port_t notify_port)
+{
+ return xcg->ops->u.gntshr.share_pages(xcg, xcg->ops_handle,
+ domid, 1, ref, writable, notify_offset, notify_port);
+}
+
+/*
+ * Unmaps the @count pages starting at @start_address, which were mapped by a
+ * call to xc_gntshr_share_*. Never logs.
+ */
+int xc_gntshr_munmap(xc_gntshr *xcg, void *start_address, uint32_t count)
+{
+ return xcg->ops->u.gntshr.munmap(xcg, xcg->ops_handle,
+ start_address, count);
+}
+
+
/*
* Local variables:
* mode: C
diff --git a/tools/libxc/xc_linux_osdep.c b/tools/libxc/xc_linux_osdep.c
index f760421..04059b8 100644
--- a/tools/libxc/xc_linux_osdep.c
+++ b/tools/libxc/xc_linux_osdep.c
@@ -34,6 +34,7 @@
#include <xen/memory.h>
#include <xen/sys/evtchn.h>
#include <xen/sys/gntdev.h>
+#include <xen/sys/gntalloc.h>
#include "xenctrl.h"
#include "xenctrlosdep.h"
@@ -656,6 +657,105 @@ static struct xc_osdep_ops linux_gnttab_ops = {
},
};
+static xc_osdep_handle linux_gntshr_open(xc_gntshr *xcg)
+{
+ int fd = open(DEVXEN "gntalloc", O_RDWR);
+
+ if ( fd == -1 )
+ return XC_OSDEP_OPEN_ERROR;
+
+ return (xc_osdep_handle)fd;
+}
+
+static int linux_gntshr_close(xc_gntshr *xcg, xc_osdep_handle h)
+{
+ int fd = (int)h;
+ return close(fd);
+}
+
+static void *linux_gntshr_share_pages(xc_gntshr *xch, xc_osdep_handle h,
+ uint32_t domid, int count,
+ uint32_t *refs, int writable,
+ uint32_t notify_offset,
+ evtchn_port_t notify_port)
+{
+ struct ioctl_gntalloc_alloc_gref *gref_info = NULL;
+ struct ioctl_gntalloc_unmap_notify notify;
+ struct ioctl_gntalloc_dealloc_gref gref_drop;
+ int fd = (int)h;
+ int err;
+ void *area = NULL;
+ gref_info = malloc(sizeof(*gref_info) + count * sizeof(uint32_t));
+ if (!gref_info)
+ return NULL;
+ gref_info->domid = domid;
+ gref_info->flags = writable ? GNTALLOC_FLAG_WRITABLE : 0;
+ gref_info->count = count;
+
+ err = ioctl(fd, IOCTL_GNTALLOC_ALLOC_GREF, gref_info);
+ if (err) {
+ PERROR("linux_gntshr_share_pages: ioctl failed");
+ goto out;
+ }
+
+ area = mmap(NULL, count * XC_PAGE_SIZE, PROT_READ | PROT_WRITE,
+ MAP_SHARED, fd, gref_info->index);
+
+ if (area == MAP_FAILED) {
+ area = NULL;
+ PERROR("linux_gntshr_share_pages: mmap failed");
+ goto out_remove_fdmap;
+ }
+
+ notify.index = gref_info->index;
+ notify.action = 0;
+ if (notify_offset >= 0) {
+ notify.index += notify_offset;
+ notify.action |= UNMAP_NOTIFY_CLEAR_BYTE;
+ }
+ if (notify_port >= 0) {
+ notify.event_channel_port = notify_port;
+ notify.action |= UNMAP_NOTIFY_SEND_EVENT;
+ }
+ if (notify.action)
+ err = ioctl(fd, IOCTL_GNTALLOC_SET_UNMAP_NOTIFY, ¬ify);
+ if (err) {
+ PERROR("linux_gntshr_share_page_notify: ioctl SET_UNMAP_NOTIFY
failed");
+ munmap(area, count * XC_PAGE_SIZE);
+ area = NULL;
+ }
+
+ memcpy(refs, gref_info->gref_ids, count * sizeof(uint32_t));
+
+ out_remove_fdmap:
+ /* Removing the mapping from the file descriptor does not cause the pages
to
+ * be deallocated until the mapping is removed.
+ */
+ gref_drop.index = gref_info->index;
+ gref_drop.count = count;
+ ioctl(fd, IOCTL_GNTALLOC_DEALLOC_GREF, &gref_drop);
+ out:
+ free(gref_info);
+ return area;
+}
+
+static int linux_gntshr_munmap(xc_gntshr *xcg, xc_osdep_handle h,
+ void *start_address, uint32_t count)
+{
+ return munmap(start_address, count);
+}
+
+static struct xc_osdep_ops linux_gntshr_ops = {
+ .open = &linux_gntshr_open,
+ .close = &linux_gntshr_close,
+
+ .u.gntshr = {
+ .share_pages = &linux_gntshr_share_pages,
+ .munmap = &linux_gntshr_munmap,
+ },
+};
+
+
static struct xc_osdep_ops *linux_osdep_init(xc_interface *xch, enum
xc_osdep_type type)
{
switch ( type )
@@ -666,6 +766,8 @@ static struct xc_osdep_ops *linux_osdep_init(xc_interface
*xch, enum xc_osdep_ty
return &linux_evtchn_ops;
case XC_OSDEP_GNTTAB:
return &linux_gnttab_ops;
+ case XC_OSDEP_GNTSHR:
+ return &linux_gntshr_ops;
default:
return NULL;
}
diff --git a/tools/libxc/xc_private.c b/tools/libxc/xc_private.c
index 09c8f23..09a91e7 100644
--- a/tools/libxc/xc_private.c
+++ b/tools/libxc/xc_private.c
@@ -258,6 +258,19 @@ int xc_gnttab_close(xc_gnttab *xcg)
return xc_interface_close_common(xcg);
}
+xc_gntshr *xc_gntshr_open(xentoollog_logger *logger,
+ unsigned open_flags)
+{
+ return xc_interface_open_common(logger, NULL, open_flags,
+ XC_OSDEP_GNTSHR);
+}
+
+int xc_gntshr_close(xc_gntshr *xcg)
+{
+ return xc_interface_close_common(xcg);
+}
+
+
static pthread_key_t errbuf_pkey;
static pthread_once_t errbuf_pkey_once = PTHREAD_ONCE_INIT;
diff --git a/tools/libxc/xenctrl.h b/tools/libxc/xenctrl.h
index 6f3165d..72a7f2d 100644
--- a/tools/libxc/xenctrl.h
+++ b/tools/libxc/xenctrl.h
@@ -115,6 +115,7 @@
typedef struct xc_interface_core xc_interface;
typedef struct xc_interface_core xc_evtchn;
typedef struct xc_interface_core xc_gnttab;
+typedef struct xc_interface_core xc_gntshr;
typedef enum xc_error_code xc_error_code;
@@ -1402,6 +1403,53 @@ grant_entry_v1_t *xc_gnttab_map_table_v1(xc_interface
*xch, int domid, int *gnt_
grant_entry_v2_t *xc_gnttab_map_table_v2(xc_interface *xch, int domid, int
*gnt_num);
/* Sometimes these don't set errno [fixme], and sometimes they don't log. */
+/*
+ * Return an fd onto the grant sharing driver. Logs errors.
+ */
+xc_gntshr *xc_gntshr_open(xentoollog_logger *logger,
+ unsigned open_flags);
+
+/*
+ * Close a handle previously allocated with xc_gntshr_open().
+ * Never logs errors.
+ */
+int xc_gntshr_close(xc_gntshr *xcg);
+
+/*
+ * Creates and shares pages with another domain.
+ *
+ * @parm xcg a handle to an open grant sharing instance
+ * @parm domid the domain to share memory with
+ * @parm count the number of pages to share
+ * @parm refs the grant references of the pages (output)
+ * @parm writable true if the other domain can write to the pages
+ * @return local mapping of the pages
+ */
+void *xc_gntshr_share_pages(xc_gntshr *xcg, uint32_t domid,
+ int count, uint32_t *refs, int writable);
+
+/*
+ * Creates and shares a page with another domain, with unmap notification.
+ *
+ * @parm xcg a handle to an open grant sharing instance
+ * @parm domid the domain to share memory with
+ * @parm refs the grant reference of the pages (output)
+ * @parm writable true if the other domain can write to the page
+ * @parm notify_offset The byte offset in the page to use for unmap
+ * notification; -1 for none.
+ * @parm notify_port The event channel port to use for unmap notify, or -1
+ * @return local mapping of the page
+ */
+void *xc_gntshr_share_page_notify(xc_gntshr *xcg, uint32_t domid,
+ uint32_t *ref, int writable,
+ uint32_t notify_offset,
+ evtchn_port_t notify_port);
+/*
+ * Unmaps the @count pages starting at @start_address, which were mapped by a
+ * call to xc_gntshr_share_*. Never logs.
+ */
+int xc_gntshr_munmap(xc_gntshr *xcg, void *start_address, uint32_t count);
+
int xc_physdev_map_pirq(xc_interface *xch,
int domid,
int index,
diff --git a/tools/libxc/xenctrlosdep.h b/tools/libxc/xenctrlosdep.h
index 1c6317e..a36c4aa 100644
--- a/tools/libxc/xenctrlosdep.h
+++ b/tools/libxc/xenctrlosdep.h
@@ -54,6 +54,7 @@ enum xc_osdep_type {
XC_OSDEP_PRIVCMD,
XC_OSDEP_EVTCHN,
XC_OSDEP_GNTTAB,
+ XC_OSDEP_GNTSHR,
};
/* Opaque handle internal to the backend */
@@ -116,6 +117,15 @@ struct xc_osdep_ops
uint32_t count);
int (*set_max_grants)(xc_gnttab *xcg, xc_osdep_handle h, uint32_t
count);
} gnttab;
+ struct {
+ void *(*share_pages)(xc_gntshr *xcg, xc_osdep_handle h,
+ uint32_t domid, int count,
+ uint32_t *refs, int writable,
+ uint32_t notify_offset,
+ evtchn_port_t notify_port);
+ int (*munmap)(xc_gntshr *xcg, xc_osdep_handle h,
+ void *start_address, uint32_t count);
+ } gntshr;
} u;
};
typedef struct xc_osdep_ops xc_osdep_ops;
--
1.7.6.2
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