From 65e5c77022c9e2723de437a931e0783920422f1a Mon Sep 17 00:00:00 2001 From: Alex Zeffertt Date: Thu, 9 Feb 2012 18:33:32 +0000 Subject: xenstored: use grant references instead of map_foreign_range make xenstored use grantref rather than map_foreign_range (which can only be used by privileged domains) This patch modifies the xenstore daemon to use xc_gnttab_map_grant_ref instead of xc_map_foreign_range where available. Previous versions of this patch have been sent to xen-devel. See http://lists.xensource.com/archives/html/xen-devel/2008-07/msg00610.html http://lists.xensource.com/archives/html/xen-devel/2009-03/msg01492.html Signed-off-by: Diego Ongaro Signed-off-by: Alex Zeffertt Signed-off-by: Daniel De Graaf Acked-by: Ian Campbell Cc: Ian Jackson Cc: Stefano Stabellini Committed-by: Ian Jackson --- tools/xenstore/xenstored_domain.c | 54 ++++++++++++++++++++++++++++++++++----- 1 file changed, 48 insertions(+), 6 deletions(-) (limited to 'tools/xenstore') diff --git a/tools/xenstore/xenstored_domain.c b/tools/xenstore/xenstored_domain.c index 443af8250a..c521e527a4 100644 --- a/tools/xenstore/xenstored_domain.c +++ b/tools/xenstore/xenstored_domain.c @@ -32,8 +32,10 @@ #include "xenstored_watch.h" #include +#include static xc_interface **xc_handle; +static xc_gnttab **xcg_handle; static evtchn_port_t virq_port; xc_evtchn *xce_handle = NULL; @@ -163,6 +165,26 @@ static int readchn(struct connection *conn, void *data, unsigned int len) return len; } +static void *map_interface(domid_t domid, unsigned long mfn) +{ + if (*xcg_handle >= 0) { + /* this is the preferred method */ + return xc_gnttab_map_grant_ref(*xcg_handle, domid, + GNTTAB_RESERVED_XENSTORE, PROT_READ|PROT_WRITE); + } else { + return xc_map_foreign_range(*xc_handle, domid, + getpagesize(), PROT_READ|PROT_WRITE, mfn); + } +} + +static void unmap_interface(void *interface) +{ + if (*xcg_handle >= 0) + xc_gnttab_munmap(*xcg_handle, interface, 1); + else + munmap(interface, getpagesize()); +} + static int destroy_domain(void *_domain) { struct domain *domain = _domain; @@ -174,8 +196,14 @@ static int destroy_domain(void *_domain) eprintf("> Unbinding port %i failed!\n", domain->port); } - if (domain->interface) - munmap(domain->interface, getpagesize()); + if (domain->interface) { + /* Domain 0 was mapped by dom0_init, so it must be unmapped + using munmap() and not the grant unmap call. */ + if (domain->domid == 0) + munmap(domain->interface, getpagesize()); + else + unmap_interface(domain->interface); + } fire_watches(NULL, "@releaseDomain", false); @@ -344,9 +372,7 @@ void do_introduce(struct connection *conn, struct buffered_data *in) domain = find_domain_by_domid(domid); if (domain == NULL) { - interface = xc_map_foreign_range( - *xc_handle, domid, - getpagesize(), PROT_READ|PROT_WRITE, mfn); + interface = map_interface(domid, mfn); if (!interface) { send_error(conn, errno); return; @@ -354,7 +380,7 @@ void do_introduce(struct connection *conn, struct buffered_data *in) /* Hang domain off "in" until we're finished. */ domain = new_domain(in, domid, port); if (!domain) { - munmap(interface, getpagesize()); + unmap_interface(interface); send_error(conn, errno); return; } @@ -552,6 +578,12 @@ static int close_xc_handle(void *_handle) return 0; } +static int close_xcg_handle(void *_handle) +{ + xc_gnttab_close(*(xc_gnttab **)_handle); + return 0; +} + /* Returns the implicit path of a connection (only domains have this) */ const char *get_implicit_path(const struct connection *conn) { @@ -603,6 +635,16 @@ void domain_init(void) talloc_set_destructor(xc_handle, close_xc_handle); + xcg_handle = talloc(talloc_autofree_context(), xc_gnttab*); + if (!xcg_handle) + barf_perror("Failed to allocate domain gnttab handle"); + + *xcg_handle = xc_gnttab_open(NULL, 0); + if (*xcg_handle < 0) + xprintf("WARNING: Failed to open connection to gnttab\n"); + else + talloc_set_destructor(xcg_handle, close_xcg_handle); + xce_handle = xc_evtchn_open(NULL, 0); if (xce_handle == NULL) -- cgit v1.2.3