On 7/23/2021 1:54 AM, Connor Kuehl wrote:
On 7/7/21 7:55 PM, isaku.yamahata@xxxxxxxxx wrote:
From: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
In TDX CPU state is also protected, thus vcpu state can't be reset by
VMM.
It assumes -action reboot=shutdown instead of silently ignoring vcpu
reset.
TDX module spec version 344425-002US doesn't support vcpu reset by
VMM. VM
needs to be destroyed and created again to emulate REBOOT_ACTION_RESET.
For simplicity, put its responsibility to management system like libvirt
because it's difficult for the current qemu implementation to destroy and
re-create KVM VM resources with keeping other resources.
If management system wants reboot behavior for its users, it needs to
- set reboot_action to REBOOT_ACTION_SHUTDOWN,
- set shutdown_action to SHUTDOWN_ACTION_PAUSE optionally and,
- subscribe VM state change and on reboot, (destroy qemu if
SHUTDOWN_ACTION_PAUSE and) start new qemu.
Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
---
target/i386/kvm/tdx.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/target/i386/kvm/tdx.c b/target/i386/kvm/tdx.c
index 1316d95209..0621317b0a 100644
--- a/target/i386/kvm/tdx.c
+++ b/target/i386/kvm/tdx.c
@@ -25,6 +25,7 @@
#include "qapi/qapi-types-misc-target.h"
#include "standard-headers/asm-x86/kvm_para.h"
#include "sysemu/sysemu.h"
+#include "sysemu/runstate-action.h"
#include "sysemu/kvm.h"
#include "sysemu/kvm_int.h"
#include "sysemu/tdx.h"
@@ -363,6 +364,19 @@ static void tdx_guest_init(Object *obj)
qemu_mutex_init(&tdx->lock);
+ /*
+ * TDX module spec version 344425-002US doesn't support reset of
vcpu by
+ * VMM. VM needs to be destroyed and created again to emulate
+ * REBOOT_ACTION_RESET. For simplicity, put its responsibility to
+ * management system like libvirt.
+ *
+ * Management system should
+ * - set reboot_action to REBOOT_ACTION_SHUTDOWN
+ * - set shutdown_action to SHUTDOWN_ACTION_PAUSE
+ * - subscribe VM state and on reboot, destroy qemu and start
new qemu
+ */
+ reboot_action = REBOOT_ACTION_SHUTDOWN;
+
tdx->debug = false;
object_property_add_bool(obj, "debug", tdx_guest_get_debug,
tdx_guest_set_debug);
I think the same effect could be accomplished with modifying
kvm_arch_cpu_check_are_resettable.
Yes. Thanks for pointing it out. We will take this approach.
