[PATCH v1 15/40] i386/tdx: Add property sept-ve-disable for tdx-guest object

Xiaoyao Li
2022-08-02T07:49:21Z

Bit 28, named SEPT_VE_DISABLE, disables EPT violation conversion to #VE
on guest TD access of PENDING pages when set to 1. Some guest OS (e.g.,
Linux TD guest) may require this bit set as 1. Otherwise refuse to boot.

Add sept-ve-disable property for tdx-guest object, for user to configure
this bit.

Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
---
qapi/qom.json | 4 +++-
target/i386/kvm/tdx.c | 24 ++++++++++++++++++++++++
2 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/qapi/qom.json b/qapi/qom.json
index 38177848abc1..2a5486bfed3e 100644
--- a/qapi/qom.json
+++ b/qapi/qom.json
@@ -835,10 +835,12 @@
#
# Properties for tdx-guest objects.
#
+# @sept-ve-disable: bit 28 of TD attributes (default: 0)
+#
# Since: 7.2
##
{ 'struct': 'TdxGuestProperties',
- 'data': { }}
+ 'data': { '*sept-ve-disable': 'bool' } }

##
# @ObjectType:
diff --git a/target/i386/kvm/tdx.c b/target/i386/kvm/tdx.c
index ecb0205651bd..bf57f270ac9d 100644
--- a/target/i386/kvm/tdx.c
+++ b/target/i386/kvm/tdx.c
@@ -30,6 +30,8 @@
(1U << KVM_FEATURE_PV_SCHED_YIELD) | \
(1U << KVM_FEATURE_MSI_EXT_DEST_ID))

+#define TDX_TD_ATTRIBUTES_SEPT_VE_DISABLE BIT_ULL(28)
+
#define TDX_ATTRIBUTES_MAX_BITS 64

static FeatureMask tdx_attrs_ctrl_fields[TDX_ATTRIBUTES_MAX_BITS] = {
@@ -490,6 +492,24 @@ out:
return r;
}

+static bool tdx_guest_get_sept_ve_disable(Object *obj, Error **errp)
+{
+ TdxGuest *tdx = TDX_GUEST(obj);
+
+ return !!(tdx->attributes & TDX_TD_ATTRIBUTES_SEPT_VE_DISABLE);
+}
+
+static void tdx_guest_set_sept_ve_disable(Object *obj, bool value, Error **errp)
+{
+ TdxGuest *tdx = TDX_GUEST(obj);
+
+ if (value) {
+ tdx->attributes |= TDX_TD_ATTRIBUTES_SEPT_VE_DISABLE;
+ } else {
+ tdx->attributes &= ~TDX_TD_ATTRIBUTES_SEPT_VE_DISABLE;
+ }
+}
+
/* tdx guest */
OBJECT_DEFINE_TYPE_WITH_INTERFACES(TdxGuest,
tdx_guest,
@@ -505,6 +525,10 @@ static void tdx_guest_init(Object *obj)
qemu_mutex_init(&tdx->lock);

tdx->attributes = 0;
+
+ object_property_add_bool(obj, "sept-ve-disable",
+ tdx_guest_get_sept_ve_disable,
+ tdx_guest_set_sept_ve_disable);
}

static void tdx_guest_finalize(Object *obj)
--
2.27.0