From 1f5552006de96f879ea0bcf342dcf4d9b3b06354 Mon Sep 17 00:00:00 2001 From: Daniel De Graaf Date: Thu, 6 Oct 2011 19:28:53 +0100 Subject: libxc: add xc_gnttab_map_grant_ref_notify Normally, when a userspace process mapping a grant crashes, the domain providing the reference receives no indication that its peer has crashed, possibly leading to unexpected freezes or timeouts. This function provides a notification of the unmap by signalling an event channel and/or clearing a specific byte in the page. This also unifies the 3 very similar grant-mapping osdep interfaces into a single function instead of introducing yet another minor variation. Signed-off-by: Daniel De Graaf Committed-by: Ian Jackson Acked-by: Ian Campbell --- tools/include/xen-sys/Linux/gntdev.h | 33 ++++++++++++++++++++++++++++++++- 1 file changed, 32 insertions(+), 1 deletion(-) (limited to 'tools/include') diff --git a/tools/include/xen-sys/Linux/gntdev.h b/tools/include/xen-sys/Linux/gntdev.h index 8bd1467893..caf6fb47ba 100644 --- a/tools/include/xen-sys/Linux/gntdev.h +++ b/tools/include/xen-sys/Linux/gntdev.h @@ -66,7 +66,7 @@ struct ioctl_gntdev_map_grant_ref { * before this ioctl is called, or an error will result. */ #define IOCTL_GNTDEV_UNMAP_GRANT_REF \ -_IOC(_IOC_NONE, 'G', 1, sizeof(struct ioctl_gntdev_unmap_grant_ref)) +_IOC(_IOC_NONE, 'G', 1, sizeof(struct ioctl_gntdev_unmap_grant_ref)) struct ioctl_gntdev_unmap_grant_ref { /* IN parameters */ /* The offset was returned by the corresponding map operation. */ @@ -116,4 +116,35 @@ struct ioctl_gntdev_set_max_grants { 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_GNTDEV_SET_UNMAP_NOTIFY \ +_IOC(_IOC_NONE, 'G', 7, sizeof(struct ioctl_gntdev_unmap_notify)) +struct ioctl_gntdev_unmap_notify { + /* IN parameters */ + /* Offset in the file descriptor for a byte within the page. This offset + * is the result of the IOCTL_GNTDEV_MAP_GRANT_REF and is the same as + * is used with mmap(). If using UNMAP_NOTIFY_CLEAR_BYTE, this is the byte + * within the page to be cleared. + */ + 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_GNTDEV_H__ */ -- cgit v1.2.3