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authorXiaoyao Li <xiaoyao.li@intel.com>2025-07-30 17:52:52 +0800
committerPaolo Bonzini <pbonzini@redhat.com>2025-09-17 19:00:58 +0200
commit0516f4b70264b9710a25718d21bd35ef463c875e (patch)
treeecb3563e5c3791feea1110d32924543dc0d94443
parentd99041a20328423bc6819ddd69b60cf98d8d84f1 (diff)
downloadfocaccia-qemu-0516f4b70264b9710a25718d21bd35ef463c875e.tar.gz
focaccia-qemu-0516f4b70264b9710a25718d21bd35ef463c875e.zip
i386/cpu: Enable SMM cpu address space under KVM
Kirill Martynov reported assertation in cpu_asidx_from_attrs() being hit
when x86_cpu_dump_state() is called to dump the CPU state[*]. It happens
when the CPU is in SMM and KVM emulation failure due to misbehaving
guest.

The root cause is that QEMU i386 never enables the SMM address space for
cpu since KVM SMM support has been added.

Enable the SMM cpu address space under KVM when the SMM is enabled for
the x86machine.

[*] https://lore.kernel.org/qemu-devel/20250523154431.506993-1-stdcalllevi@yandex-team.ru/

Reported-by: Kirill Martynov <stdcalllevi@yandex-team.ru>
Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Tested-by: Kirill Martynov <stdcalllevi@yandex-team.ru>
Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Link: https://lore.kernel.org/r/20250730095253.1833411-2-xiaoyao.li@intel.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
-rw-r--r--system/physmem.c5
-rw-r--r--target/i386/kvm/kvm-cpu.c10
-rw-r--r--target/i386/kvm/kvm.c5
3 files changed, 15 insertions, 5 deletions
diff --git a/system/physmem.c b/system/physmem.c
index ddd58e9eb8..ae8ecd50ea 100644
--- a/system/physmem.c
+++ b/system/physmem.c
@@ -793,9 +793,6 @@ void cpu_address_space_init(CPUState *cpu, int asidx,
         cpu->as = as;
     }
 
-    /* KVM cannot currently support multiple address spaces. */
-    assert(asidx == 0 || !kvm_enabled());
-
     if (!cpu->cpu_ases) {
         cpu->cpu_ases = g_new0(CPUAddressSpace, cpu->num_ases);
         cpu->cpu_ases_count = cpu->num_ases;
@@ -818,8 +815,6 @@ void cpu_address_space_destroy(CPUState *cpu, int asidx)
 
     assert(cpu->cpu_ases);
     assert(asidx >= 0 && asidx < cpu->num_ases);
-    /* KVM cannot currently support multiple address spaces. */
-    assert(asidx == 0 || !kvm_enabled());
 
     cpuas = &cpu->cpu_ases[asidx];
     if (tcg_enabled()) {
diff --git a/target/i386/kvm/kvm-cpu.c b/target/i386/kvm/kvm-cpu.c
index 89a7953659..1dc1ba9b48 100644
--- a/target/i386/kvm/kvm-cpu.c
+++ b/target/i386/kvm/kvm-cpu.c
@@ -13,6 +13,7 @@
 #include "qapi/error.h"
 #include "system/system.h"
 #include "hw/boards.h"
+#include "hw/i386/x86.h"
 
 #include "kvm_i386.h"
 #include "accel/accel-cpu-target.h"
@@ -91,6 +92,15 @@ static bool kvm_cpu_realizefn(CPUState *cs, Error **errp)
         kvm_set_guest_phys_bits(cs);
     }
 
+    /*
+     * When SMM is enabled, there is 2 address spaces. Otherwise only 1.
+     *
+     * Only initialize address space 0 here, the second one for SMM is
+     * initialized at register_smram_listener() after machine init done.
+     */
+    cs->num_ases = x86_machine_is_smm_enabled(X86_MACHINE(current_machine)) ? 2 : 1;
+    cpu_address_space_init(cs, 0, "cpu-memory", cs->memory);
+
     return true;
 }
 
diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
index 34e74f2447..d191d7177f 100644
--- a/target/i386/kvm/kvm.c
+++ b/target/i386/kvm/kvm.c
@@ -2704,6 +2704,7 @@ static MemoryRegion smram_as_mem;
 
 static void register_smram_listener(Notifier *n, void *unused)
 {
+    CPUState *cpu;
     MemoryRegion *smram =
         (MemoryRegion *) object_resolve_path("/machine/smram", NULL);
 
@@ -2728,6 +2729,10 @@ static void register_smram_listener(Notifier *n, void *unused)
     address_space_init(&smram_address_space, &smram_as_root, "KVM-SMRAM");
     kvm_memory_listener_register(kvm_state, &smram_listener,
                                  &smram_address_space, 1, "kvm-smram");
+
+    CPU_FOREACH(cpu) {
+        cpu_address_space_init(cpu, 1, "cpu-smm", &smram_as_root);
+    }
 }
 
 static void *kvm_msr_energy_thread(void *data)