[PATCH] numa: forbid '-numa node, mem' for 5.1 and newer machine types

[PATCH] numa: forbid '-numa node, mem' for 5.1 and newer machine types

[Igor Mammedov]

Deprecation period is run out and it's a time to flip the switch
introduced by cd5ff8333a.  Disable legacy option for new machine
types (since 5.1) and amend documentation.

'-numa node,memdev' shall be used instead of disabled option
with new machine types.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
---
 - rebased on top of current master
 - move compat mode from 4.2 to 5.0

CC: peter.maydell@linaro.org
CC: ehabkost@redhat.com
CC: marcel.apfelbaum@gmail.com
CC: mst@redhat.com
CC: pbonzini@redhat.com
CC: rth@twiddle.net
CC: david@gibson.dropbear.id.au
CC: libvir-list@redhat.com
CC: qemu-arm@nongnu.org
CC: qemu-ppc@nongnu.org
---
 docs/system/deprecated.rst | 17 -----------------
 hw/arm/virt.c              |  2 +-
 hw/core/numa.c             |  6 ++++++
 hw/i386/pc.c               |  1 -
 hw/i386/pc_piix.c          |  1 +
 hw/i386/pc_q35.c           |  1 +
 hw/ppc/spapr.c             |  2 +-
 qemu-options.hx            |  9 +++++----
 8 files changed, 15 insertions(+), 24 deletions(-)

diff --git a/docs/system/deprecated.rst b/docs/system/deprecated.rst
index f0061f94aa..57edc075c2 100644
--- a/docs/system/deprecated.rst
+++ b/docs/system/deprecated.rst
@@ -101,23 +101,6 @@ error in the future.
 The ``-realtime mlock=on|off`` argument has been replaced by the
 ``-overcommit mem-lock=on|off`` argument.
 
-``-numa node,mem=``\ *size* (since 4.1)
-'''''''''''''''''''''''''''''''''''''''
-
-The parameter ``mem`` of ``-numa node`` is used to assign a part of
-guest RAM to a NUMA node. But when using it, it's impossible to manage specified
-RAM chunk on the host side (like bind it to a host node, setting bind policy, ...),
-so guest end-ups with the fake NUMA configuration with suboptiomal performance.
-However since 2014 there is an alternative way to assign RAM to a NUMA node
-using parameter ``memdev``, which does the same as ``mem`` and adds
-means to actualy manage node RAM on the host side. Use parameter ``memdev``
-with *memory-backend-ram* backend as an replacement for parameter ``mem``
-to achieve the same fake NUMA effect or a properly configured
-*memory-backend-file* backend to actually benefit from NUMA configuration.
-In future new machine versions will not accept the option but it will still
-work with old machine types. User can check QAPI schema to see if the legacy
-option is supported by looking at MachineInfo::numa-mem-supported property.
-
 ``-numa`` node (without memory specified) (since 4.1)
 '''''''''''''''''''''''''''''''''''''''''''''''''''''
 
diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index 37462a6f78..063d4703f7 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -2262,7 +2262,6 @@ static void virt_machine_class_init(ObjectClass *oc, void *data)
     hc->pre_plug = virt_machine_device_pre_plug_cb;
     hc->plug = virt_machine_device_plug_cb;
     hc->unplug_request = virt_machine_device_unplug_request_cb;
-    mc->numa_mem_supported = true;
     mc->nvdimm_supported = true;
     mc->auto_enable_numa_with_memhp = true;
     mc->default_ram_id = "mach-virt.ram";
@@ -2375,6 +2374,7 @@ DEFINE_VIRT_MACHINE_AS_LATEST(5, 1)
 static void virt_machine_5_0_options(MachineClass *mc)
 {
     virt_machine_5_1_options(mc);
+    mc->numa_mem_supported = true;
 }
 DEFINE_VIRT_MACHINE(5, 0)
 
diff --git a/hw/core/numa.c b/hw/core/numa.c
index 316bc50d75..05be412e59 100644
--- a/hw/core/numa.c
+++ b/hw/core/numa.c
@@ -117,6 +117,12 @@ static void parse_numa_node(MachineState *ms, NumaNodeOptions *node,
     }
 
     if (node->has_mem) {
+        if (!mc->numa_mem_supported) {
+            error_setg(errp, "Parameter -numa node,mem is not supported by this"
+                      " machine type. Use -numa node,memdev instead");
+            return;
+        }
+
         numa_info[nodenr].node_mem = node->mem;
         if (!qtest_enabled()) {
             warn_report("Parameter -numa node,mem is deprecated,"
diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 2128f3d6fe..a86136069c 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -1960,7 +1960,6 @@ static void pc_machine_class_init(ObjectClass *oc, void *data)
     hc->unplug = pc_machine_device_unplug_cb;
     mc->default_cpu_type = TARGET_DEFAULT_CPU_TYPE;
     mc->nvdimm_supported = true;
-    mc->numa_mem_supported = true;
     mc->default_ram_id = "pc.ram";
 
     object_class_property_add(oc, PC_MACHINE_DEVMEM_REGION_SIZE, "int",
diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
index f66e1d73ce..8955436efa 100644
--- a/hw/i386/pc_piix.c
+++ b/hw/i386/pc_piix.c
@@ -438,6 +438,7 @@ static void pc_i440fx_5_0_machine_options(MachineClass *m)
     pc_i440fx_5_1_machine_options(m);
     m->alias = NULL;
     m->is_default = false;
+    m->numa_mem_supported = true;
     compat_props_add(m->compat_props, hw_compat_5_0, hw_compat_5_0_len);
     compat_props_add(m->compat_props, pc_compat_5_0, pc_compat_5_0_len);
 }
diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
index 4ba8ac8774..af6b32adb7 100644
--- a/hw/i386/pc_q35.c
+++ b/hw/i386/pc_q35.c
@@ -366,6 +366,7 @@ static void pc_q35_5_0_machine_options(MachineClass *m)
 {
     pc_q35_5_1_machine_options(m);
     m->alias = NULL;
+    m->numa_mem_supported = true;
     compat_props_add(m->compat_props, hw_compat_5_0, hw_compat_5_0_len);
     compat_props_add(m->compat_props, pc_compat_5_0, pc_compat_5_0_len);
 }
diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 3b1a5ed865..210d61d1b3 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -4511,7 +4511,6 @@ static void spapr_machine_class_init(ObjectClass *oc, void *data)
      * in which LMBs are represented and hot-added
      */
     mc->numa_mem_align_shift = 28;
-    mc->numa_mem_supported = true;
     mc->auto_enable_numa = true;
 
     smc->default_caps.caps[SPAPR_CAP_HTM] = SPAPR_CAP_OFF;
@@ -4599,6 +4598,7 @@ static void spapr_machine_5_0_class_options(MachineClass *mc)
 {
     spapr_machine_5_1_class_options(mc);
     compat_props_add(mc->compat_props, hw_compat_5_0, hw_compat_5_0_len);
+    mc->numa_mem_supported = true;
 }
 
 DEFINE_SPAPR_MACHINE(5_0, "5.0", false);
diff --git a/qemu-options.hx b/qemu-options.hx
index 93bde2bbc8..196f468786 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -239,10 +239,11 @@ SRST
         -numa node,nodeid=0 -numa node,nodeid=1 \
         -numa cpu,node-id=0,socket-id=0 -numa cpu,node-id=1,socket-id=1
 
-    '\ ``mem``\ ' assigns a given RAM amount to a node. '\ ``memdev``\ '
-    assigns RAM from a given memory backend device to a node. If
-    '\ ``mem``\ ' and '\ ``memdev``\ ' are omitted in all nodes, RAM is
-    split equally between them.
+    Legacy '\ ``mem``\ ' assigns a given RAM amount to a node (not supported
+    for 5.1 and newer machine types). '\ ``memdev``\ ' assigns RAM from
+    a given memory backend device to a node. If '\ ``mem``\ ' and
+    '\ ``memdev``\ ' are omitted in all nodes, RAM is split equally between them.
+
 
     '\ ``mem``\ ' and '\ ``memdev``\ ' are mutually exclusive.
     Furthermore, if one node uses '\ ``memdev``\ ', all of them have to
-- 
2.18.4

Re: [PATCH] numa: forbid '-numa node, mem' for 5.1 and newer machine types

[Michal Privoznik]

On 6/2/20 10:41 AM, Igor Mammedov wrote:
> Deprecation period is run out and it's a time to flip the switch
> introduced by cd5ff8333a.  Disable legacy option for new machine
> types (since 5.1) and amend documentation.
> 
> '-numa node,memdev' shall be used instead of disabled option
> with new machine types.
> 
> Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> ---
>   - rebased on top of current master
>   - move compat mode from 4.2 to 5.0
> 
> CC: peter.maydell@linaro.org
> CC: ehabkost@redhat.com
> CC: marcel.apfelbaum@gmail.com
> CC: mst@redhat.com
> CC: pbonzini@redhat.com
> CC: rth@twiddle.net
> CC: david@gibson.dropbear.id.au
> CC: libvir-list@redhat.com
> CC: qemu-arm@nongnu.org
> CC: qemu-ppc@nongnu.org
> ---
>   docs/system/deprecated.rst | 17 -----------------
>   hw/arm/virt.c              |  2 +-
>   hw/core/numa.c             |  6 ++++++
>   hw/i386/pc.c               |  1 -
>   hw/i386/pc_piix.c          |  1 +
>   hw/i386/pc_q35.c           |  1 +
>   hw/ppc/spapr.c             |  2 +-
>   qemu-options.hx            |  9 +++++----
>   8 files changed, 15 insertions(+), 24 deletions(-)

This works with libvirt perfectly.

Reviewed-by: Michal Privoznik <mprivozn@redhat.com>

Michal

Re: [PATCH] numa: forbid '-numa node, mem' for 5.1 and newer machine types

[Eric Blake]

On 6/2/20 3:41 AM, Igor Mammedov wrote:
> Deprecation period is run out and it's a time to flip the switch
> introduced by cd5ff8333a.  Disable legacy option for new machine
> types (since 5.1) and amend documentation.
> 
> '-numa node,memdev' shall be used instead of disabled option
> with new machine types.
> 
> Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> ---
>   - rebased on top of current master
>   - move compat mode from 4.2 to 5.0
> 

>   docs/system/deprecated.rst | 17 -----------------

Lately, when we remove something, we've been moving the documentation 
from 'will be deprecated' to a later section of the document 'has been 
removed', so that the history is not lost.  But this diffstat says you 
just deleted, rather than moved, that hunk.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org

Re: [PATCH] numa: forbid '-numa node, mem' for 5.1 and newer machine types

[Igor Mammedov]

On Thu, 4 Jun 2020 07:22:51 -0500
Eric Blake <eblake@redhat.com> wrote:

> On 6/2/20 3:41 AM, Igor Mammedov wrote:
> > Deprecation period is run out and it's a time to flip the switch
> > introduced by cd5ff8333a.  Disable legacy option for new machine
> > types (since 5.1) and amend documentation.
> > 
> > '-numa node,memdev' shall be used instead of disabled option
> > with new machine types.
> > 
> > Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> > ---
> >   - rebased on top of current master
> >   - move compat mode from 4.2 to 5.0
> >   
> 
> >   docs/system/deprecated.rst | 17 -----------------  
> 
> Lately, when we remove something, we've been moving the documentation 
> from 'will be deprecated' to a later section of the document 'has been 
> removed', so that the history is not lost.  But this diffstat says you 
> just deleted, rather than moved, that hunk.
> 
I didn't know that,
I'll send v2 with this hunk moved to removed section