* [PATCH v3 1/2] tools/xl: add available Xenstore features to xl info output
2025-07-31 8:42 [PATCH v3 0/2] tools: add support for domain specific Xenstore features Juergen Gross
@ 2025-07-31 8:42 ` Juergen Gross
2025-07-31 8:42 ` [PATCH v3 2/2] tools: allow to limit xenstore features via guest config Juergen Gross
1 sibling, 0 replies; 4+ messages in thread
From: Juergen Gross @ 2025-07-31 8:42 UTC (permalink / raw)
To: xen-devel; +Cc: Juergen Gross, Anthony PERARD, Jason Andryuk
Add the Xenstore feature value to the output of "xl info" in order to
prepare for a future capability to limit Xenstore features visible by
a guest.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jason Andryuk <jason.andryuk@amd.com>
Acked-by: Anthony PERARD <anthony.perard@vates.tech>
---
tools/xl/Makefile | 3 ++-
tools/xl/xl_info.c | 22 ++++++++++++++++++++++
2 files changed, 24 insertions(+), 1 deletion(-)
diff --git a/tools/xl/Makefile b/tools/xl/Makefile
index d742e96a5b..ad577cdd70 100644
--- a/tools/xl/Makefile
+++ b/tools/xl/Makefile
@@ -13,6 +13,7 @@ LDFLAGS += $(PTHREAD_LDFLAGS)
CFLAGS_XL += $(CFLAGS_libxenlight)
CFLAGS_XL += $(CFLAGS_libxenutil)
+CFLAGS_XL += $(CFLAGS_libxenstore)
CFLAGS_XL += -Wshadow
XL_OBJS-$(CONFIG_X86) = xl_psr.o
@@ -32,7 +33,7 @@ $(XL_OBJS): CFLAGS += -include $(XEN_ROOT)/tools/config.h # libxl_json.h needs i
all: xl
xl: $(XL_OBJS)
- $(CC) $(LDFLAGS) -o $@ $(XL_OBJS) $(LDLIBS_libxenutil) $(LDLIBS_libxenlight) $(LDLIBS_libxentoollog) -lyajl $(APPEND_LDFLAGS)
+ $(CC) $(LDFLAGS) -o $@ $(XL_OBJS) $(LDLIBS_libxenutil) $(LDLIBS_libxenlight) $(LDLIBS_libxentoollog) $(LDLIBS_libxenstore) -lyajl $(APPEND_LDFLAGS)
.PHONY: install
install: all
diff --git a/tools/xl/xl_info.c b/tools/xl/xl_info.c
index 72e87eac46..eb019e3ee9 100644
--- a/tools/xl/xl_info.c
+++ b/tools/xl/xl_info.c
@@ -28,6 +28,7 @@
#include <libxl_utils.h>
#include <libxlutil.h>
#include <xen-tools/arm-arch-capabilities.h>
+#include <xenstore.h>
#include "xl.h"
#include "xl_utils.h"
@@ -333,6 +334,25 @@ static void output_topologyinfo(void)
return;
}
+static void output_xenstore_info(void)
+{
+ struct xs_handle *xsh;
+ unsigned int features = 0;
+
+ xsh = xs_open(0);
+ if (!xsh) {
+ fprintf(stderr, "xs_open failed.\n");
+ return;
+ }
+
+ /* Ignore error, default to "0" for features. */
+ xs_get_features_supported(xsh, &features);
+
+ maybe_printf("xenstore_features : 0x%08x\n", features);
+
+ xs_close(xsh);
+}
+
static void print_info(int numa)
{
output_nodeinfo();
@@ -345,6 +365,8 @@ static void print_info(int numa)
}
output_xeninfo();
+ output_xenstore_info();
+
maybe_printf("xend_config_format : 4\n");
return;
--
2.43.0
^ permalink raw reply related [flat|nested] 4+ messages in thread* [PATCH v3 2/2] tools: allow to limit xenstore features via guest config
2025-07-31 8:42 [PATCH v3 0/2] tools: add support for domain specific Xenstore features Juergen Gross
2025-07-31 8:42 ` [PATCH v3 1/2] tools/xl: add available Xenstore features to xl info output Juergen Gross
@ 2025-07-31 8:42 ` Juergen Gross
2025-07-31 14:05 ` Anthony PERARD
1 sibling, 1 reply; 4+ messages in thread
From: Juergen Gross @ 2025-07-31 8:42 UTC (permalink / raw)
To: xen-devel
Cc: Juergen Gross, Anthony PERARD, Nick Rosbrook, George Dunlap,
Jason Andryuk
Add a guest config parameter "xenstore_feature_mask" allowing to limit
the Xenstore features the guest can see and use. This can be needed in
order to allow migrating a guest to a host running a Xenstore version
providing less features than the source host.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jason Andryuk <jason.andryuk@amd.com>
Acked-by: Nick Rosbrook <enr0n@ubuntu.com> # tools/golang
---
V2:
- fix typo (Jason Andryuk)
V3:
- use LOGED for error logging (Anthony Perard)
- don't leak vm_path in case of error (Anthony Perard)
---
docs/man/xl.cfg.5.pod.in | 36 ++++++++++++++++++++++++++++
tools/golang/xenlight/helpers.gen.go | 2 ++
tools/golang/xenlight/types.gen.go | 1 +
tools/include/libxl.h | 6 +++++
tools/libs/light/libxl_dom.c | 17 ++++++++++++-
tools/libs/light/libxl_types.idl | 1 +
tools/xl/xl_parse.c | 3 +++
7 files changed, 65 insertions(+), 1 deletion(-)
diff --git a/docs/man/xl.cfg.5.pod.in b/docs/man/xl.cfg.5.pod.in
index 5362fb0e9a..f0c920b39d 100644
--- a/docs/man/xl.cfg.5.pod.in
+++ b/docs/man/xl.cfg.5.pod.in
@@ -714,6 +714,42 @@ If this option is not specified then it will default to B<false>.
=back
+=head3 Xenstore related settings
+
+=over 4
+
+=item B<xenstore_feature_mask=NUMBER>
+
+Specify which Xenstore features are visible for the guest.
+
+This might be needed when a guest should be able to be migrated to a host
+running a Xenstore implementation with less features than the one the guest
+is created on.
+
+The visible features are specified via a binary or of the following
+values:
+
+=over 4
+
+=item B<0x00000001>
+
+Xenstore is capable to reconnect to a guest.
+
+=item B<0x00000002>
+
+Xenstore will present an error value in case it disconnects due to an error
+condition.
+
+=back
+
+The features supported by the running Xenstore instance can be retrieved
+via the B<xl info> command in dom0.
+
+The default value is B<0xffffffff>, meaning that all possible Xenstore
+features are visible by the guest.
+
+=back
+
=head2 Devices
The following options define the paravirtual, emulated and physical
diff --git a/tools/golang/xenlight/helpers.gen.go b/tools/golang/xenlight/helpers.gen.go
index b43aad7d00..667030cbd7 100644
--- a/tools/golang/xenlight/helpers.gen.go
+++ b/tools/golang/xenlight/helpers.gen.go
@@ -1175,6 +1175,7 @@ return fmt.Errorf("converting field Vpmu: %v", err)
if err := x.TrapUnmappedAccesses.fromC(&xc.trap_unmapped_accesses);err != nil {
return fmt.Errorf("converting field TrapUnmappedAccesses: %v", err)
}
+x.XenstoreFeatureMask = uint32(xc.xenstore_feature_mask)
return nil}
@@ -1710,6 +1711,7 @@ return fmt.Errorf("converting field Vpmu: %v", err)
if err := x.TrapUnmappedAccesses.toC(&xc.trap_unmapped_accesses); err != nil {
return fmt.Errorf("converting field TrapUnmappedAccesses: %v", err)
}
+xc.xenstore_feature_mask = C.uint32_t(x.XenstoreFeatureMask)
return nil
}
diff --git a/tools/golang/xenlight/types.gen.go b/tools/golang/xenlight/types.gen.go
index 4777f528b5..e26b3cdfc7 100644
--- a/tools/golang/xenlight/types.gen.go
+++ b/tools/golang/xenlight/types.gen.go
@@ -608,6 +608,7 @@ Altp2MCount uint32
VmtraceBufKb int
Vpmu Defbool
TrapUnmappedAccesses Defbool
+XenstoreFeatureMask uint32
}
type DomainBuildInfoTypeUnion interface {
diff --git a/tools/include/libxl.h b/tools/include/libxl.h
index d6b6e5d2dd..185f74d8a8 100644
--- a/tools/include/libxl.h
+++ b/tools/include/libxl.h
@@ -654,6 +654,12 @@
*/
#define LIBXL_HAVE_DT_OVERLAY_DOMAIN 1
+/*
+ * LIBXL_HAVE_XENSTORE_FEATURE_MASK indicates the presence of
+ * xenstore_feature_mask in struct libxl_domain_build_info.
+ */
+#define LIBXL_HAVE_XENSTORE_FEATURE_MASK 1
+
/*
* libxl memory management
*
diff --git a/tools/libs/light/libxl_dom.c b/tools/libs/light/libxl_dom.c
index a61085ca3b..05ebc69534 100644
--- a/tools/libs/light/libxl_dom.c
+++ b/tools/libs/light/libxl_dom.c
@@ -494,9 +494,24 @@ retry_transaction:
if (!xs_transaction_end(ctx->xsh, t, 0))
if (errno == EAGAIN)
goto retry_transaction;
+
+ if (info->xenstore_feature_mask != ~0U) {
+ unsigned int features;
+
+ if (xs_get_features_supported(ctx->xsh, &features) &&
+ !xs_set_features_domain(ctx->xsh, domid,
+ features & info->xenstore_feature_mask)) {
+ LOGED(ERROR, domid, "Failed to set Xenstore features");
+ rc = ERROR_FAIL;
+ goto out;
+ }
+ }
+
xs_introduce_domain(ctx->xsh, domid, state->store_mfn, state->store_port);
+
+ out:
free(vm_path);
- return 0;
+ return rc;
}
static int set_vnuma_info(libxl__gc *gc, uint32_t domid,
diff --git a/tools/libs/light/libxl_types.idl b/tools/libs/light/libxl_types.idl
index fe251649f3..a6030a2dbd 100644
--- a/tools/libs/light/libxl_types.idl
+++ b/tools/libs/light/libxl_types.idl
@@ -739,6 +739,7 @@ libxl_domain_build_info = Struct("domain_build_info",[
("vpmu", libxl_defbool),
("trap_unmapped_accesses", libxl_defbool),
+ ("xenstore_feature_mask", uint32, {'init_val': '~0U'}),
], dir=DIR_IN,
copy_deprecated_fn="libxl__domain_build_info_copy_deprecated",
diff --git a/tools/xl/xl_parse.c b/tools/xl/xl_parse.c
index 28cdbf07c2..90c9386f5b 100644
--- a/tools/xl/xl_parse.c
+++ b/tools/xl/xl_parse.c
@@ -1409,6 +1409,9 @@ void parse_config_data(const char *config_source,
if (!xlu_cfg_get_string (config, "pool", &buf, 0))
xlu_cfg_replace_string(config, "pool", &c_info->pool_name, 0);
+ if (!xlu_cfg_get_long (config, "xenstore_feature_mask", &l, 0))
+ b_info->xenstore_feature_mask = l;
+
libxl_domain_build_info_init_type(b_info, c_info->type);
if (b_info->type == LIBXL_DOMAIN_TYPE_PVH) {
--
2.43.0
^ permalink raw reply related [flat|nested] 4+ messages in thread