From: Andres Lagar-Cavilla <andres@lagarcavilla.org>
To: xen-devel@lists.xensource.com
Cc: ian.campbell@citrix.com, andres@gridcentric.ca, tim@xen.org,
keir.xen@gmail.com, JBeulich@suse.com, ian.jackson@citrix.com,
adin@gridcentric.ca
Subject: [PATCH 02 of 13] x86/mm: Update mem sharing interface to (re)allow sharing of grants
Date: Wed, 25 Jan 2012 22:32:26 -0500 [thread overview]
Message-ID: <61e164d6e9566bc5418d.1327548746@xdev.gridcentric.ca> (raw)
In-Reply-To: <patchbomb.1327548744@xdev.gridcentric.ca>
xen/arch/x86/mm/mem_sharing.c | 57 ++++++++++++++++++++++++++++++++++++------
xen/include/public/domctl.h | 13 +++++++++
2 files changed, 61 insertions(+), 9 deletions(-)
Previosuly, the mem sharing code would return an opaque handle to index shared
pages (and nominees) in its global hash table. By removing the hash table, the
new interfaces requires a gfn and a version. However, when sharing grants, the
caller provides a grant ref and a version. Update interface to handle this
case.
The use case for grant sharing is when sharing from within a backend (e.g.
memshr + blktap2), in which case the backend is only exposed to grant
references.
Signed-off-by: Andres Lagar-Cavilla <andres@lagarcavilla.org>
Signed-off-by: Adin Scannell <adin@scannell.ca>
diff -r bcc4215663e8 -r 61e164d6e956 xen/arch/x86/mm/mem_sharing.c
--- a/xen/arch/x86/mm/mem_sharing.c
+++ b/xen/arch/x86/mm/mem_sharing.c
@@ -728,18 +728,57 @@ int mem_sharing_domctl(struct domain *d,
case XEN_DOMCTL_MEM_EVENT_OP_SHARING_SHARE:
{
- unsigned long sgfn = mec->u.share.source_gfn;
- shr_handle_t sh = mec->u.share.source_handle;
- struct domain *cd = get_domain_by_id(mec->u.share.client_domain);
- if ( cd )
+ unsigned long sgfn, cgfn;
+ struct domain *cd;
+ shr_handle_t sh, ch;
+
+ if ( !mem_sharing_enabled(d) )
+ return -EINVAL;
+
+ cd = get_domain_by_id(mec->u.share.client_domain);
+ if ( !cd )
+ return -ESRCH;
+
+ if ( !mem_sharing_enabled(cd) )
{
- unsigned long cgfn = mec->u.share.client_gfn;
- shr_handle_t ch = mec->u.share.client_handle;
- rc = mem_sharing_share_pages(d, sgfn, sh, cd, cgfn, ch);
put_domain(cd);
+ return -EINVAL;
}
- else
- return -EEXIST;
+
+ if ( XEN_DOMCTL_MEM_SHARING_FIELD_IS_GREF(mec->u.share.source_gfn) )
+ {
+ grant_ref_t gref = (grant_ref_t)
+ (XEN_DOMCTL_MEM_SHARING_FIELD_GET_GREF(
+ mec->u.share.source_gfn));
+ if ( mem_sharing_gref_to_gfn(d, gref, &sgfn) < 0 )
+ {
+ put_domain(cd);
+ return -EINVAL;
+ }
+ } else {
+ sgfn = mec->u.share.source_gfn;
+ }
+
+ if ( XEN_DOMCTL_MEM_SHARING_FIELD_IS_GREF(mec->u.share.client_gfn) )
+ {
+ grant_ref_t gref = (grant_ref_t)
+ (XEN_DOMCTL_MEM_SHARING_FIELD_GET_GREF(
+ mec->u.share.client_gfn));
+ if ( mem_sharing_gref_to_gfn(cd, gref, &cgfn) < 0 )
+ {
+ put_domain(cd);
+ return -EINVAL;
+ }
+ } else {
+ cgfn = mec->u.share.client_gfn;
+ }
+
+ sh = mec->u.share.source_handle;
+ ch = mec->u.share.client_handle;
+
+ rc = mem_sharing_share_pages(d, sgfn, sh, cd, cgfn, ch);
+
+ put_domain(cd);
}
break;
diff -r bcc4215663e8 -r 61e164d6e956 xen/include/public/domctl.h
--- a/xen/include/public/domctl.h
+++ b/xen/include/public/domctl.h
@@ -775,6 +775,19 @@ DEFINE_XEN_GUEST_HANDLE(xen_domctl_mem_e
#define XEN_DOMCTL_MEM_SHARING_S_HANDLE_INVALID (-10)
#define XEN_DOMCTL_MEM_SHARING_C_HANDLE_INVALID (-9)
+/* The following allows sharing of grant refs. This is useful
+ * for sharing utilities sitting as "filters" in IO backends
+ * (e.g. memshr + blktap(2)). The IO backend is only exposed
+ * to grant references, and this allows sharing of the grefs */
+#define XEN_DOMCTL_MEM_SHARING_FIELD_IS_GREF_FLAG (1ULL << 62)
+
+#define XEN_DOMCTL_MEM_SHARING_FIELD_MAKE_GREF(field, val) \
+ (field) = (XEN_DOMCTL_MEM_SHARING_FIELD_IS_GREF_FLAG | val)
+#define XEN_DOMCTL_MEM_SHARING_FIELD_IS_GREF(field) \
+ ((field) & XEN_DOMCTL_MEM_SHARING_FIELD_IS_GREF_FLAG)
+#define XEN_DOMCTL_MEM_SHARING_FIELD_GET_GREF(field) \
+ ((field) & (~XEN_DOMCTL_MEM_SHARING_FIELD_IS_GREF_FLAG))
+
struct xen_domctl_mem_sharing_op {
uint8_t op; /* XEN_DOMCTL_MEM_EVENT_OP_* */
next prev parent reply other threads:[~2012-01-26 3:32 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-26 3:32 [PATCH 00 of 13] Sharing overhaul V4 Andres Lagar-Cavilla
2012-01-26 3:32 ` [PATCH 01 of 13] x86/mm: Eliminate hash table in sharing code as index of shared mfns Andres Lagar-Cavilla
2012-01-26 3:32 ` Andres Lagar-Cavilla [this message]
2012-01-26 3:32 ` [PATCH 03 of 13] x86/mm: Add per-page locking for memory sharing, when audits are disabled Andres Lagar-Cavilla
2012-01-26 3:32 ` [PATCH 04 of 13] x86/mm: Enforce lock ordering for sharing page locks Andres Lagar-Cavilla
2012-01-26 3:32 ` [PATCH 05 of 13] x86/mm: Check how many mfns are shared, in addition to how many are saved Andres Lagar-Cavilla
2012-01-26 3:32 ` [PATCH 06 of 13] x86/mm: New domctl: add a shared page to the physmap Andres Lagar-Cavilla
2012-01-26 3:32 ` [PATCH 07 of 13] Add the ability to poll stats about shared memory via the console Andres Lagar-Cavilla
2012-01-26 3:32 ` [PATCH 08 of 13] x86/mm: use RCU in mem sharing audit list, eliminate global lock completely Andres Lagar-Cavilla
2012-01-26 3:32 ` [PATCH 09 of 13] Update memshr API and tools Andres Lagar-Cavilla
2012-01-26 3:32 ` [PATCH 10 of 13] Tools: Expose to libxc the total number of shared frames and space saved Andres Lagar-Cavilla
2012-01-26 3:32 ` [PATCH 11 of 13] Tools: Add a sharing command to xl for information about shared pages Andres Lagar-Cavilla
2012-01-26 3:32 ` [PATCH 12 of 13] Memshrtool: tool to test and exercise the sharing subsystem Andres Lagar-Cavilla
2012-01-27 18:21 ` Ian Jackson
2012-01-27 18:27 ` Andres Lagar-Cavilla
2012-01-26 3:32 ` [PATCH 13 of 13] x86/mm: Sharing overhaul style improvements Andres Lagar-Cavilla
2012-01-26 12:54 ` [PATCH 00 of 13] Sharing overhaul V4 Tim Deegan
2012-01-26 13:08 ` Andres Lagar-Cavilla
2012-01-26 13:16 ` Olaf Hering
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