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[Qemu-devel] [PATCH] pc: make sure that guest isn't able to unplug the f
From: |
Igor Mammedov |
Subject: |
[Qemu-devel] [PATCH] pc: make sure that guest isn't able to unplug the first cpu |
Date: |
Mon, 27 Aug 2018 13:07:10 +0200 |
The first cpu unplug wasn't ever supported and corresponding
monitor/qmp commands refuse to unplug it. However guest is able
to issue eject request either using following command:
# echo 1 >/sys/devices/system/cpu/cpu0/firmware_node/eject
or directly writing to cpu hotplug registers, which makes
qemu crash with SIGSEGV following back trace:
kvm_flush_coalesced_mmio_buffer ()
while (ring->first != ring->last)
...
qemu_flush_coalesced_mmio_buffer
prepare_mmio_access
flatview_read_continue
flatview_read
address_space_read_full
address_space_rw
kvm_cpu_exec(cpu!0)
qemu_kvm_cpu_thread_fn
the reason for which is that ring == KVMState::coalesced_mmio_ring
happens to be a part of 1st CPU that was uplugged by guest.
Fix it by forbidding 1st cpu unplug from guest side and in addition
remove CPU0._EJ0 ACPI method to make clear that unplug of the first
CPU is not supported.
Signed-off-by: Igor Mammedov <address@hidden>
---
CCing spapr and s390x folks in case targets need to prevent 1st CPU unplug as
well
CC: address@hidden
CC: address@hidden
CC: address@hidden
CC: address@hidden
CC: address@hidden
CC: address@hidden
---
hw/acpi/cpu.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/hw/acpi/cpu.c b/hw/acpi/cpu.c
index 5ae595e..4bb8371 100644
--- a/hw/acpi/cpu.c
+++ b/hw/acpi/cpu.c
@@ -117,7 +117,7 @@ static void cpu_hotplug_wr(void *opaque, hwaddr addr,
uint64_t data,
DeviceState *dev = NULL;
HotplugHandler *hotplug_ctrl = NULL;
- if (!cdev->cpu) {
+ if (!cdev->cpu || cdev->cpu == first_cpu) {
trace_cpuhp_acpi_ejecting_invalid_cpu(cpu_st->selector);
break;
}
@@ -541,9 +541,11 @@ void build_cpus_aml(Aml *table, MachineState *machine,
CPUHotplugFeatures opts,
aml_buffer(madt_buf->len, (uint8_t *)madt_buf->data)));
g_array_free(madt_buf, true);
- method = aml_method("_EJ0", 1, AML_NOTSERIALIZED);
- aml_append(method, aml_call1(CPU_EJECT_METHOD, uid));
- aml_append(dev, method);
+ if (CPU(arch_ids->cpus[i].cpu) != first_cpu) {
+ method = aml_method("_EJ0", 1, AML_NOTSERIALIZED);
+ aml_append(method, aml_call1(CPU_EJECT_METHOD, uid));
+ aml_append(dev, method);
+ }
method = aml_method("_OST", 3, AML_SERIALIZED);
aml_append(method,
--
2.7.4
- [Qemu-devel] [PATCH] pc: make sure that guest isn't able to unplug the first cpu,
Igor Mammedov <=
- Re: [Qemu-devel] [PATCH] pc: make sure that guest isn't able to unplug the first cpu, David Hildenbrand, 2018/08/27
- Re: [Qemu-devel] [PATCH] pc: make sure that guest isn't able to unplug the first cpu, Greg Kurz, 2018/08/27
- Re: [Qemu-devel] [PATCH] pc: make sure that guest isn't able to unplug the first cpu, Igor Mammedov, 2018/08/27
- Re: [Qemu-devel] [PATCH] pc: make sure that guest isn't able to unplug the first cpu, David Gibson, 2018/08/27
- Re: [Qemu-devel] [PATCH] pc: make sure that guest isn't able to unplug the first cpu, Igor Mammedov, 2018/08/28
- Re: [Qemu-devel] [PATCH] pc: make sure that guest isn't able to unplug the first cpu, David Gibson, 2018/08/29
- Re: [Qemu-devel] [PATCH] pc: make sure that guest isn't able to unplug the first cpu, Igor Mammedov, 2018/08/29
- Re: [Qemu-devel] [PATCH] pc: make sure that guest isn't able to unplug the first cpu, Michael S. Tsirkin, 2018/08/29
- Re: [Qemu-devel] [PATCH] pc: make sure that guest isn't able to unplug the first cpu, Igor Mammedov, 2018/08/29
- Re: [Qemu-devel] [PATCH] pc: make sure that guest isn't able to unplug the first cpu, Laszlo Ersek, 2018/08/29