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acpi: provide _PXM method for CPU devices if QEMU is started numa enabled

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Workaround for long standing issue where Linux kernel
assigns hotplugged CPU to 1st numa node as it discards
proximity for possible CPUs from SRAT after it's parsed.

_PXM method allows linux query proximity directly from
hotplugged CPU object, which allows Linux to assing CPU
to the correct numa node.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Marcel Apfelbaum <marcel@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Igor Mammedov 2016-10-05 17:51:24 +02:00 committed by Michael S. Tsirkin
parent 6bea1ddf8b
commit 271119313c
1 changed files with 12 additions and 0 deletions
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12
hw/acpi/cpu.c
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@ -4,6 +4,7 @@
#include "qapi/error.h"
#include "qapi-event.h"
#include "trace.h"
#include "sysemu/numa.h"
#define ACPI_CPU_HOTPLUG_REG_LEN 12
#define ACPI_CPU_SELECTOR_OFFSET_WR 0
@ -503,6 +504,7 @@ void build_cpus_aml(Aml *table, MachineState *machine, CPUHotplugFeatures opts,
/* build Processor object for each processor */
for (i = 0; i < arch_ids->len; i++) {
int j;
Aml *dev;
Aml *uid = aml_int(i);
GArray *madt_buf = g_array_new(0, 1, 1);
@ -546,6 +548,16 @@ void build_cpus_aml(Aml *table, MachineState *machine, CPUHotplugFeatures opts,
aml_arg(1), aml_arg(2))
);
aml_append(dev, method);
/* Linux guests discard SRAT info for non-present CPUs
* as a result _PXM is required for all CPUs which might
* be hot-plugged. For simplicity, add it for all CPUs.
*/
j = numa_get_node_for_cpu(i);
if (j < nb_numa_nodes) {
aml_append(dev, aml_name_decl("_PXM", aml_int(j)));
}
aml_append(cpus_dev, dev);
}
}