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target/i386: Fix sanity check on max APIC ID / X2APIC enablement

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The check on x86ms->apic_id_limit in pc_machine_done() had two problems.

Firstly, we need KVM to support the X2APIC API in order to allow IRQ
delivery to APICs >= 255. So we need to call/check kvm_enable_x2apic(),
which was done elsewhere in *some* cases but not all.

Secondly, microvm needs the same check. So move it from pc_machine_done()
to x86_cpus_init() where it will work for both.

The check in kvm_cpu_instance_init() is now redundant and can be dropped.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Acked-by: Claudio Fontana <cfontana@suse.de>
Message-Id: <20220314142544.150555-1-dwmw2@infradead.org>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
David Woodhouse 2022-03-14 14:25:41 +00:00 committed by Michael S. Tsirkin
parent 5181db132b
commit dc89f32d92
3 changed files with 17 additions and 9 deletions
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8
hw/i386/pc.c
View File

@ -744,14 +744,6 @@ void pc_machine_done(Notifier *notifier, void *data)
/* update FW_CFG_NB_CPUS to account for -device added CPUs */
fw_cfg_modify_i16(x86ms->fw_cfg, FW_CFG_NB_CPUS, x86ms->boot_cpus);
}
if (x86ms->apic_id_limit > 255 && !xen_enabled() &&
!kvm_irqchip_in_kernel()) {
error_report("current -smp configuration requires kernel "
"irqchip support.");
exit(EXIT_FAILURE);
}
}
void pc_guest_info_init(PCMachineState *pcms)

16
hw/i386/x86.c
View File

@ -38,6 +38,7 @@
#include "sysemu/replay.h"
#include "sysemu/sysemu.h"
#include "sysemu/cpu-timers.h"
#include "sysemu/xen.h"
#include "trace.h"
#include "hw/i386/x86.h"
@ -122,6 +123,21 @@ void x86_cpus_init(X86MachineState *x86ms, int default_cpu_version)
*/
x86ms->apic_id_limit = x86_cpu_apic_id_from_index(x86ms,
ms->smp.max_cpus - 1) + 1;
/*
* Can we support APIC ID 255 or higher?
*
* Under Xen: yes.
* With userspace emulated lapic: no
* With KVM's in-kernel lapic: only if X2APIC API is enabled.
*/
if (x86ms->apic_id_limit > 255 && !xen_enabled() &&
(!kvm_irqchip_in_kernel() || !kvm_enable_x2apic())) {
error_report("current -smp configuration requires kernel "
"irqchip and X2APIC API support.");
exit(EXIT_FAILURE);
}
possible_cpus = mc->possible_cpu_arch_ids(ms);
for (i = 0; i < ms->smp.cpus; i++) {
x86_cpu_new(x86ms, possible_cpus->cpus[i].arch_id, &error_fatal);

2
target/i386/kvm/kvm-cpu.c
View File

@ -171,7 +171,7 @@ static void kvm_cpu_instance_init(CPUState *cs)
/* only applies to builtin_x86_defs cpus */
if (!kvm_irqchip_in_kernel()) {
x86_cpu_change_kvm_default("x2apic", "off");
} else if (kvm_irqchip_is_split() && kvm_enable_x2apic()) {
} else if (kvm_irqchip_is_split()) {
x86_cpu_change_kvm_default("kvm-msi-ext-dest-id", "on");
}