[PULL 02/18] i386/kvm/cpu: Init SMM cpu address space for hotplugged CPUs

[Paolo Bonzini <pbonzini@redhat.com>]

From: Xiaoyao Li <xiaoyao.li@intel.com>

The SMM cpu address space is initialized in a machine_init_done
notifier. It only runs once when QEMU starts up, which leads to the
issue that for any hotplugged CPU after the machine is ready, SMM
cpu address space doesn't get initialized.

Fix the issue by initializing the SMM cpu address space in x86_cpu_plug()
when the cpu is hotplugged.

Fixes: 591f817d819f ("target/i386: Define enum X86ASIdx for x86's address spaces")
Reported-by: Peter Maydell <peter.maydell@linaro.org>
Closes: https://lore.kernel.org/qemu-devel/CAFEAcA_3kkZ+a5rTZGmK8W5K6J7qpYD31HkvjBnxWr-fGT2h_A@mail.gmail.com/
Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Link: https://lore.kernel.org/r/20251014094216.164306-2-xiaoyao.li@intel.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 target/i386/kvm/kvm_i386.h |  1 +
 hw/i386/x86-common.c       | 11 +++++++++++
 target/i386/kvm/kvm.c      |  6 ++++++
 3 files changed, 18 insertions(+)

diff --git a/target/i386/kvm/kvm_i386.h b/target/i386/kvm/kvm_i386.h
index 5c908fdd6a5..2b653442f4d 100644
--- a/target/i386/kvm/kvm_i386.h
+++ b/target/i386/kvm/kvm_i386.h
@@ -74,6 +74,7 @@ uint32_t kvm_x86_build_cpuid(CPUX86State *env, struct kvm_cpuid_entry2 *entries,
                              uint32_t cpuid_i);
 #endif /* CONFIG_KVM */
 
+void kvm_smm_cpu_address_space_init(X86CPU *cpu);
 void kvm_pc_setup_irq_routing(bool pci_enabled);
 
 #endif
diff --git a/hw/i386/x86-common.c b/hw/i386/x86-common.c
index 7512be64d67..5716191fff1 100644
--- a/hw/i386/x86-common.c
+++ b/hw/i386/x86-common.c
@@ -183,6 +183,17 @@ void x86_cpu_plug(HotplugHandler *hotplug_dev,
         fw_cfg_modify_i16(x86ms->fw_cfg, FW_CFG_NB_CPUS, x86ms->boot_cpus);
     }
 
+    /*
+     * Non-hotplugged CPUs get their SMM cpu address space initialized in
+     * machine init done notifier: register_smram_listener().
+     *
+     * We need initialize the SMM cpu address space for the hotplugged CPU
+     * specifically.
+     */
+    if (kvm_enabled() && dev->hotplugged && x86_machine_is_smm_enabled(x86ms)) {
+        kvm_smm_cpu_address_space_init(cpu);
+    }
+
     found_cpu = x86_find_cpu_slot(MACHINE(x86ms), cpu->apic_id, NULL);
     found_cpu->cpu = CPU(dev);
 out:
diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
index f7a6ef650af..4dea1ed8f0f 100644
--- a/target/i386/kvm/kvm.c
+++ b/target/i386/kvm/kvm.c
@@ -2748,6 +2748,12 @@ static void register_smram_listener(Notifier *n, void *unused)
     }
 }
 
+/* It should only be called in cpu's hotplug callback */
+void kvm_smm_cpu_address_space_init(X86CPU *cpu)
+{
+    cpu_address_space_init(CPU(cpu), X86ASIdx_SMM, "cpu-smm", &smram_as_root);
+}
+
 static void *kvm_msr_energy_thread(void *data)
 {
     KVMState *s = data;
-- 
2.51.1