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i386/cpu: Enable SMM cpu address space under KVM

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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>
This commit is contained in:
Xiaoyao Li 2025-07-30 17:52:52 +08:00 • committed by Paolo Bonzini
parent d99041a203
commit 0516f4b702
3 changed files with 15 additions and 5 deletions
Download patch file Download diff file Expand all files Collapse all files

5
system/physmem.c
View file

@ -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()) {

10
target/i386/kvm/kvm-cpu.c
View file

@ -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;
}

5
target/i386/kvm/kvm.c
View file

@ -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)