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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH 1/2] x86/mem-sharing: Bulk mem-sharing entire domains
Currently mem-sharing can be performed on a page-by-page base from the control
domain. However, when completely deduplicating (cloning) a VM, this requires
at least 3 hypercalls per page. As the user has to loop through all pages up
to max_gpfn, this process is very slow and wasteful.
This patch introduces a new mem_sharing memop for bulk deduplication where
the user doesn't have to separately nominate each page in both the source and
destination domain, and the looping over all pages happen in the hypervisor.
This significantly reduces the overhead of completely deduplicating entire
domains.
Signed-off-by: Tamas K Lengyel <tlengyel@xxxxxxxxxxx>
Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
Cc: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
Cc: Ian Campbell <ian.campbell@xxxxxxxxxx>
Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
Cc: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
Cc: Keir Fraser <keir@xxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
tools/libxc/include/xenctrl.h | 11 +++++
tools/libxc/xc_memshr.c | 14 ++++++
xen/arch/x86/mm/mem_sharing.c | 90 ++++++++++++++++++++++++++++++++++++++-
xen/arch/x86/x86_64/compat/mm.c | 6 ++-
xen/arch/x86/x86_64/mm.c | 6 ++-
xen/include/asm-x86/mem_sharing.h | 3 +-
xen/include/public/memory.h | 1 +
7 files changed, 124 insertions(+), 7 deletions(-)
diff --git a/tools/libxc/include/xenctrl.h b/tools/libxc/include/xenctrl.h
index 3bfa00b..dd82549 100644
--- a/tools/libxc/include/xenctrl.h
+++ b/tools/libxc/include/xenctrl.h
@@ -2594,6 +2594,17 @@ int xc_memshr_add_to_physmap(xc_interface *xch,
domid_t client_domain,
unsigned long client_gfn);
+/* Allows to deduplicate the entire memory of a client domain in bulk. Using
+ * this function is equivalent of calling xc_memshr_nominate_gfn for each gfn
+ * in the two domains followed by xc_memshr_share_gfns.
+ *
+ * May fail with EINVAL if the source and client domain have different
+ * memory size or if memory sharing is not enabled on either of the domains.
+ */
+int xc_memshr_bulk_dedup(xc_interface *xch,
+ domid_t source_domain,
+ domid_t client_domain);
+
/* Debug calls: return the number of pages referencing the shared frame backing
* the input argument. Should be one or greater.
*
diff --git a/tools/libxc/xc_memshr.c b/tools/libxc/xc_memshr.c
index deb0aa4..ecb0f5c 100644
--- a/tools/libxc/xc_memshr.c
+++ b/tools/libxc/xc_memshr.c
@@ -181,6 +181,20 @@ int xc_memshr_add_to_physmap(xc_interface *xch,
return xc_memshr_memop(xch, source_domain, &mso);
}
+int xc_memshr_bulk_dedup(xc_interface *xch,
+ domid_t source_domain,
+ domid_t client_domain)
+{
+ xen_mem_sharing_op_t mso;
+
+ memset(&mso, 0, sizeof(mso));
+
+ mso.op = XENMEM_sharing_op_bulk_dedup;
+ mso.u.share.client_domain = client_domain;
+
+ return xc_memshr_memop(xch, source_domain, &mso);
+}
+
int xc_memshr_domain_resume(xc_interface *xch,
domid_t domid)
{
diff --git a/xen/arch/x86/mm/mem_sharing.c b/xen/arch/x86/mm/mem_sharing.c
index a95e105..319f52f 100644
--- a/xen/arch/x86/mm/mem_sharing.c
+++ b/xen/arch/x86/mm/mem_sharing.c
@@ -29,6 +29,7 @@
#include <xen/rcupdate.h>
#include <xen/guest_access.h>
#include <xen/vm_event.h>
+#include <xen/hypercall.h>
#include <asm/page.h>
#include <asm/string.h>
#include <asm/p2m.h>
@@ -1293,9 +1294,44 @@ int relinquish_shared_pages(struct domain *d)
return rc;
}
-int mem_sharing_memop(XEN_GUEST_HANDLE_PARAM(xen_mem_sharing_op_t) arg)
+static long bulk_share(struct domain *d, struct domain *cd,
+ unsigned long max_gfn, unsigned long start,
+ uint32_t mask)
{
- int rc;
+ long rc = 0;
+ shr_handle_t sh, ch;
+
+ while( start <= max_gfn )
+ {
+ if ( mem_sharing_nominate_page(d, start, 0, &sh) != 0 )
+ goto next;
+
+ if ( mem_sharing_nominate_page(cd, start, 0, &ch) != 0 )
+ goto next;
+
+ mem_sharing_share_pages(d, start, sh, cd, start, ch);
+
+next:
+ ++start;
+
+ /* Check for continuation if it's not the last iteration. */
+ if ( start < max_gfn && !(start & mask)
+ && hypercall_preempt_check() )
+ {
+ rc = start;
+ break;
+ }
+ }
+
+ return rc;
+}
+
+
+long mem_sharing_memop(unsigned long cmd,
+ XEN_GUEST_HANDLE_PARAM(xen_mem_sharing_op_t) arg)
+{
+ unsigned long start_iter = cmd & ~MEMOP_CMD_MASK;
+ long rc;
xen_mem_sharing_op_t mso;
struct domain *d;
@@ -1467,6 +1503,56 @@ int
mem_sharing_memop(XEN_GUEST_HANDLE_PARAM(xen_mem_sharing_op_t) arg)
}
break;
+ case XENMEM_sharing_op_bulk_dedup:
+ {
+ unsigned long max_sgfn, max_cgfn;
+ struct domain *cd;
+
+ rc = -EINVAL;
+ if ( !mem_sharing_enabled(d) )
+ goto out;
+
+ rc = rcu_lock_live_remote_domain_by_id(mso.u.share.client_domain,
+ &cd);
+ if ( rc )
+ goto out;
+
+ rc = xsm_mem_sharing_op(XSM_DM_PRIV, d, cd, mso.op);
+ if ( rc )
+ {
+ rcu_unlock_domain(cd);
+ goto out;
+ }
+
+ if ( !mem_sharing_enabled(cd) )
+ {
+ rcu_unlock_domain(cd);
+ rc = -EINVAL;
+ goto out;
+ }
+
+ max_sgfn = domain_get_maximum_gpfn(d);
+ max_cgfn = domain_get_maximum_gpfn(cd);
+
+ if ( max_sgfn != max_cgfn || max_sgfn < start_iter )
+ {
+ rcu_unlock_domain(cd);
+ rc = -EINVAL;
+ goto out;
+ }
+
+ rc = bulk_share(d, cd, max_sgfn, start_iter, MEMOP_CMD_MASK);
+ if ( rc > 0 )
+ {
+ ASSERT(!(rc & MEMOP_CMD_MASK));
+ rc = hypercall_create_continuation(__HYPERVISOR_memory_op,
"lh",
+ XENMEM_sharing_op | rc,
arg);
+ }
+
+ rcu_unlock_domain(cd);
+ }
+ break;
+
case XENMEM_sharing_op_debug_gfn:
{
unsigned long gfn = mso.u.debug.u.gfn;
diff --git a/xen/arch/x86/x86_64/compat/mm.c b/xen/arch/x86/x86_64/compat/mm.c
index d034bd0..15cf16f 100644
--- a/xen/arch/x86/x86_64/compat/mm.c
+++ b/xen/arch/x86/x86_64/compat/mm.c
@@ -53,8 +53,9 @@ int compat_arch_memory_op(unsigned long cmd,
XEN_GUEST_HANDLE_PARAM(void) arg)
compat_pfn_t mfn;
unsigned int i;
int rc = 0;
+ int op = cmd & MEMOP_CMD_MASK;
- switch ( cmd )
+ switch ( op )
{
case XENMEM_set_memory_map:
{
@@ -190,7 +191,8 @@ int compat_arch_memory_op(unsigned long cmd,
XEN_GUEST_HANDLE_PARAM(void) arg)
return mem_paging_memop(guest_handle_cast(arg, xen_mem_paging_op_t));
case XENMEM_sharing_op:
- return mem_sharing_memop(guest_handle_cast(arg, xen_mem_sharing_op_t));
+ return mem_sharing_memop(cmd,
+ guest_handle_cast(arg, xen_mem_sharing_op_t));
default:
rc = -ENOSYS;
diff --git a/xen/arch/x86/x86_64/mm.c b/xen/arch/x86/x86_64/mm.c
index d918002..14c2d33 100644
--- a/xen/arch/x86/x86_64/mm.c
+++ b/xen/arch/x86/x86_64/mm.c
@@ -930,8 +930,9 @@ long subarch_memory_op(unsigned long cmd,
XEN_GUEST_HANDLE_PARAM(void) arg)
xen_pfn_t mfn, last_mfn;
unsigned int i;
long rc = 0;
+ int op = cmd & MEMOP_CMD_MASK;
- switch ( cmd )
+ switch ( op )
{
case XENMEM_machphys_mfn_list:
if ( copy_from_guest(&xmml, arg, 1) )
@@ -1011,7 +1012,8 @@ long subarch_memory_op(unsigned long cmd,
XEN_GUEST_HANDLE_PARAM(void) arg)
return mem_paging_memop(guest_handle_cast(arg, xen_mem_paging_op_t));
case XENMEM_sharing_op:
- return mem_sharing_memop(guest_handle_cast(arg, xen_mem_sharing_op_t));
+ return mem_sharing_memop(cmd,
+ guest_handle_cast(arg, xen_mem_sharing_op_t));
default:
rc = -ENOSYS;
diff --git a/xen/include/asm-x86/mem_sharing.h
b/xen/include/asm-x86/mem_sharing.h
index 3840a14..6d344d2 100644
--- a/xen/include/asm-x86/mem_sharing.h
+++ b/xen/include/asm-x86/mem_sharing.h
@@ -89,7 +89,8 @@ static inline int mem_sharing_unshare_page(struct domain *d,
*/
int mem_sharing_notify_enomem(struct domain *d, unsigned long gfn,
bool_t allow_sleep);
-int mem_sharing_memop(XEN_GUEST_HANDLE_PARAM(xen_mem_sharing_op_t) arg);
+long mem_sharing_memop(unsigned long cmd,
+ XEN_GUEST_HANDLE_PARAM(xen_mem_sharing_op_t) arg);
int mem_sharing_domctl(struct domain *d,
xen_domctl_mem_sharing_op_t *mec);
int mem_sharing_audit(void);
diff --git a/xen/include/public/memory.h b/xen/include/public/memory.h
index 320de91..4bc9fc9 100644
--- a/xen/include/public/memory.h
+++ b/xen/include/public/memory.h
@@ -447,6 +447,7 @@ DEFINE_XEN_GUEST_HANDLE(xen_mem_access_op_t);
#define XENMEM_sharing_op_debug_gref 5
#define XENMEM_sharing_op_add_physmap 6
#define XENMEM_sharing_op_audit 7
+#define XENMEM_sharing_op_bulk_dedup 8
#define XENMEM_SHARING_OP_S_HANDLE_INVALID (-10)
#define XENMEM_SHARING_OP_C_HANDLE_INVALID (-9)
--
2.1.4
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