From dc89f32d92bba795b0665f075b78d8881cf67ab3 Mon Sep 17 00:00:00 2001 From: David Woodhouse Date: Mon, 14 Mar 2022 14:25:41 +0000 Subject: [PATCH] target/i386: Fix sanity check on max APIC ID / X2APIC enablement 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 Acked-by: Claudio Fontana Message-Id: <20220314142544.150555-1-dwmw2@infradead.org> Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- hw/i386/pc.c | 8 -------- hw/i386/x86.c | 16 ++++++++++++++++ target/i386/kvm/kvm-cpu.c | 2 +- 3 files changed, 17 insertions(+), 9 deletions(-) diff --git a/hw/i386/pc.c b/hw/i386/pc.c index 312eb9e400..15f37d8dc6 100644 --- a/hw/i386/pc.c +++ b/hw/i386/pc.c @@ -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) diff --git a/hw/i386/x86.c b/hw/i386/x86.c index 79ebdface6..f79e720cc2 100644 --- a/hw/i386/x86.c +++ b/hw/i386/x86.c @@ -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); diff --git a/target/i386/kvm/kvm-cpu.c b/target/i386/kvm/kvm-cpu.c index 5eb955ce9a..7237378a7d 100644 --- a/target/i386/kvm/kvm-cpu.c +++ b/target/i386/kvm/kvm-cpu.c @@ -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"); }