From: Ani Sinha <anisinha@redhat.com>

When the confidential virtual machine KVM file descriptor changes due to the
guest reset, some TDX specific setup steps needs to be done again. This
includes finalizing the initial guest launch state again. This change
re-executes some parts of the TDX setup during the device reset phaze using a
resettable interface. This finalizes the guest launch state again and locks
it in. Machine done notifier which was previously used is no longer needed as
the same code is now executed as a part of VM reset.

Signed-off-by: Ani Sinha <anisinha@redhat.com>
Link: https://lore.kernel.org/r/20260225035000.385950-18-anisinha@redhat.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 target/i386/kvm/tdx.h        |  1 +
 target/i386/kvm/tdx.c        | 38 +++++++++++++++++++++++++++++++-----
 target/i386/kvm/trace-events |  3 +++
 3 files changed, 37 insertions(+), 5 deletions(-)

diff --git a/target/i386/kvm/tdx.h b/target/i386/kvm/tdx.h
index 1c38faf9834..264fbe530cc 100644
--- a/target/i386/kvm/tdx.h
+++ b/target/i386/kvm/tdx.h
@@ -70,6 +70,7 @@ typedef struct TdxGuest {
 
     uint32_t event_notify_vector;
     uint32_t event_notify_apicid;
+    ResettableState reset_state;
 } TdxGuest;
 
 #ifdef CONFIG_TDX
diff --git a/target/i386/kvm/tdx.c b/target/i386/kvm/tdx.c
index fd8e3de9693..37e91d95e1e 100644
--- a/target/i386/kvm/tdx.c
+++ b/target/i386/kvm/tdx.c
@@ -19,6 +19,7 @@
 #include "crypto/hash.h"
 #include "system/kvm_int.h"
 #include "system/runstate.h"
+#include "system/reset.h"
 #include "system/system.h"
 #include "system/ramblock.h"
 #include "system/address-spaces.h"
@@ -38,6 +39,7 @@
 #include "kvm_i386.h"
 #include "tdx.h"
 #include "tdx-quote-generator.h"
+#include "trace.h"
 
 #include "standard-headers/asm-x86/kvm_para.h"
 
@@ -389,9 +391,19 @@ static void tdx_finalize_vm(Notifier *notifier, void *unused)
     CONFIDENTIAL_GUEST_SUPPORT(tdx_guest)->ready = true;
 }
 
-static Notifier tdx_machine_done_notify = {
-    .notify = tdx_finalize_vm,
-};
+static void tdx_handle_reset(Object *obj, ResetType type)
+{
+    if (!runstate_is_running() && !phase_check(PHASE_MACHINE_READY)) {
+        return;
+    }
+
+    if (!kvm_enable_hypercall(BIT_ULL(KVM_HC_MAP_GPA_RANGE))) {
+        error_setg(&error_fatal, "KVM_HC_MAP_GPA_RANGE not enabled for guest");
+    }
+
+    tdx_finalize_vm(NULL, NULL);
+    trace_tdx_handle_reset();
+}
 
 /*
  * Some CPUID bits change from fixed1 to configurable bits when TDX module
@@ -738,8 +750,6 @@ static int tdx_kvm_init(ConfidentialGuestSupport *cgs, Error **errp)
      */
     kvm_readonly_mem_allowed = false;
 
-    qemu_add_machine_init_done_notifier(&tdx_machine_done_notify);
-
     tdx_guest = tdx;
     return 0;
 }
@@ -1505,6 +1515,7 @@ OBJECT_DEFINE_TYPE_WITH_INTERFACES(TdxGuest,
                                    TDX_GUEST,
                                    X86_CONFIDENTIAL_GUEST,
                                    { TYPE_USER_CREATABLE },
+                                   { TYPE_RESETTABLE_INTERFACE },
                                    { NULL })
 
 static void tdx_guest_init(Object *obj)
@@ -1538,16 +1549,24 @@ static void tdx_guest_init(Object *obj)
 
     tdx->event_notify_vector = -1;
     tdx->event_notify_apicid = -1;
+    qemu_register_resettable(obj);
 }
 
 static void tdx_guest_finalize(Object *obj)
 {
 }
 
+static ResettableState *tdx_reset_state(Object *obj)
+{
+    TdxGuest *tdx = TDX_GUEST(obj);
+    return &tdx->reset_state;
+}
+
 static void tdx_guest_class_init(ObjectClass *oc, const void *data)
 {
     ConfidentialGuestSupportClass *klass = CONFIDENTIAL_GUEST_SUPPORT_CLASS(oc);
     X86ConfidentialGuestClass *x86_klass = X86_CONFIDENTIAL_GUEST_CLASS(oc);
+    ResettableClass *rc = RESETTABLE_CLASS(oc);
 
     klass->kvm_init = tdx_kvm_init;
     klass->can_rebuild_guest_state = true;
@@ -1555,4 +1574,13 @@ static void tdx_guest_class_init(ObjectClass *oc, const void *data)
     x86_klass->cpu_instance_init = tdx_cpu_instance_init;
     x86_klass->adjust_cpuid_features = tdx_adjust_cpuid_features;
     x86_klass->check_features = tdx_check_features;
+
+    /*
+     * the exit phase makes sure sev handles reset after all legacy resets
+     * have taken place (in the hold phase) and IGVM has also properly
+     * set up the boot state.
+     */
+    rc->phases.exit = tdx_handle_reset;
+    rc->get_state = tdx_reset_state;
+
 }
diff --git a/target/i386/kvm/trace-events b/target/i386/kvm/trace-events
index 2d213c9f9b6..a3862345714 100644
--- a/target/i386/kvm/trace-events
+++ b/target/i386/kvm/trace-events
@@ -14,3 +14,6 @@ kvm_xen_soft_reset(void) ""
 kvm_xen_set_shared_info(uint64_t gfn) "shared info at gfn 0x%" PRIx64
 kvm_xen_set_vcpu_attr(int cpu, int type, uint64_t gpa) "vcpu attr cpu %d type %d gpa 0x%" PRIx64
 kvm_xen_set_vcpu_callback(int cpu, int vector) "callback vcpu %d vector %d"
+
+# tdx.c
+tdx_handle_reset(void) ""
-- 
2.53.0