Hi Rahul
On 06/09/2022 14:40, Rahul Singh wrote:
Introduce a new "xen,enhanced" dom0less property value "no-xenstore" to
disable xenstore interface for dom0less guests.
Signed-off-by: Rahul Singh <rahul.si...@arm.com>
---
Changes in v4:
- Implement defines for dom0less features
Changes in v3:
- new patch in this version
---
docs/misc/arm/device-tree/booting.txt | 4 ++++
xen/arch/arm/domain_build.c | 10 ++++++----
xen/arch/arm/include/asm/kernel.h | 23 +++++++++++++++++++++--
3 files changed, 31 insertions(+), 6 deletions(-)
diff --git a/docs/misc/arm/device-tree/booting.txt
b/docs/misc/arm/device-tree/booting.txt
index 98253414b8..1b0dca1454 100644
--- a/docs/misc/arm/device-tree/booting.txt
+++ b/docs/misc/arm/device-tree/booting.txt
@@ -204,6 +204,10 @@ with the following properties:
- "disabled"
Xen PV interfaces are disabled.
+ - no-xenstore
+ Xen PV interfaces, including grant-table will be enabled but xenstore
Please use "All default" in front. So it is clear that everything is
enabled but xenstore.
+ will be disabled for the VM.
+
If the xen,enhanced property is present with no value, it defaults
to "enabled". If the xen,enhanced property is not present, PV
interfaces are disabled.
diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index 707e247f6a..0b164ef595 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -2891,7 +2891,7 @@ static int __init prepare_dtb_domU(struct domain *d,
struct kernel_info *kinfo)
goto err;
}
- if ( kinfo->dom0less_enhanced )
+ if ( kinfo->dom0less_feature & DOM0LESS_ENHANCED_NO_XS )
{
ret = make_hypervisor_node(d, kinfo, addrcells, sizecells);
if ( ret )
@@ -3209,10 +3209,12 @@ static int __init construct_domU(struct domain *d,
(rc == 0 && !strcmp(dom0less_enhanced, "enabled")) )
{
if ( hardware_domain )
- kinfo.dom0less_enhanced = true;
+ kinfo.dom0less_feature = DOM0LESS_ENHANCED;
else
- panic("Tried to use xen,enhanced without dom0\n");
+ panic("At the moment, Xenstore support requires dom0 to be
present\n");
}
+ else if ( rc == 0 && !strcmp(dom0less_enhanced, "no-xenstore") )
+ kinfo.dom0less_feature = DOM0LESS_ENHANCED_NO_XS;
if ( vcpu_create(d, 0) == NULL )
return -ENOMEM;
@@ -3252,7 +3254,7 @@ static int __init construct_domU(struct domain *d,
if ( rc < 0 )
return rc;
- if ( kinfo.dom0less_enhanced )
+ if ( kinfo.dom0less_feature & DOM0LESS_XENSTORE )
{
ASSERT(hardware_domain);
rc = alloc_xenstore_evtchn(d);
diff --git a/xen/arch/arm/include/asm/kernel.h
b/xen/arch/arm/include/asm/kernel.h
index c4dc039b54..ad240494ea 100644
--- a/xen/arch/arm/include/asm/kernel.h
+++ b/xen/arch/arm/include/asm/kernel.h
@@ -9,6 +9,25 @@
#include <xen/device_tree.h>
#include <asm/setup.h>
+/*
+ * List of possible features for dom0less domUs
+ *
+ * DOM0LESS_ENHANCED_NO_XS: Notify the OS it is running on top of Xen. All the
+ * default features (excluding Xenstore) will be
+ * available. Note that an OS *must* not rely on the
+ * availability of Xen features if this is not set.
+ * DOM0LESS_XENSTORE: Xenstore will be enabled for the VM. This feature
+ * can't be enabled without the
+ * DOM0LESS_ENHANCED_NO_XS.
+ * DOM0LESS_ENHANCED: Notify the OS it is running on top of Xen. All the
+ * default features (including Xenstore) will be
+ * available. Note that an OS *must* not rely on the
+ * availability of Xen features if this is not set.
+ */
+#define DOM0LESS_ENHANCED_NO_XS BIT(0, U)
+#define DOM0LESS_XENSTORE BIT(1, U)
+#define DOM0LESS_ENHANCED (DOM0LESS_ENHANCED_NO_XS | DOM0LESS_XENSTORE)
+
struct kernel_info {
#ifdef CONFIG_ARM_64
enum domain_type type;
@@ -36,8 +55,8 @@ struct kernel_info {
/* Enable pl011 emulation */
bool vpl011;
- /* Enable PV drivers */
- bool dom0less_enhanced;
+ /* Enable/Disable PV drivers interface,grant table, evtchn or xenstore */
The part after "," is technically wrong because it also affects other
interfaces. But I would drop it to avoid any stale comment (we may add
new one in the futures).
Cheers,
--
Julien Grall
