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Re: [Qemu-ppc] [PATCH v6 01/11] machine: Don't allow CPU toplogies with


From: Alexey Kardashevskiy
Subject: Re: [Qemu-ppc] [PATCH v6 01/11] machine: Don't allow CPU toplogies with partially filled cores
Date: Wed, 13 Jan 2016 10:24:53 +1100
User-agent: Mozilla/5.0 (X11; Linux i686 on x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.0

On 01/08/2016 05:55 PM, Bharata B Rao wrote:
Prevent guests from booting with CPU topologies that have partially
filled CPU cores or can result in partially filled CPU cores after
CPU hotplug like

-smp 15,sockets=1,cores=4,threads=4,maxcpus=16 or
-smp 15,sockets=1,cores=4,threads=4,maxcpus=17.

This is enforced by introducing MachineClass::validate_smp_config()
that gets called from generic SMP parsing code. Machine type versions
that don't want to enforce this can override this method.

TODO: Only sPAPR and PC changes are done in this patch, other archs
will be touched after there is agreement on this approach.

Signed-off-by: Bharata B Rao <address@hidden>
---
  hw/core/machine.c   | 20 ++++++++++++++++++++
  hw/i386/pc_piix.c   |  7 +++++++
  hw/i386/pc_q35.c    |  7 +++++++
  hw/ppc/spapr.c      |  7 +++++++
  include/hw/boards.h |  1 +
  vl.c                |  4 ++++
  6 files changed, 46 insertions(+)

diff --git a/hw/core/machine.c b/hw/core/machine.c
index c46ddc7..b66c101 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -336,6 +336,25 @@ static void machine_init_notify(Notifier *notifier, void 
*data)
      foreach_dynamic_sysbus_device(error_on_sysbus_device, NULL);
  }

+static int validate_smp_config_generic(int smp_cpus, int max_cpus,
+                                       int smp_threads)
+{
+        if (smp_cpus % smp_threads) {
+            error_report("cpu topology: "
+                         "smp_cpus (%u) should be multiple of threads (%u) ",
+                         smp_cpus, smp_threads);
+            return 1;
+        }
+
+        if (max_cpus % smp_threads) {
+            error_report("cpu topology: "
+                         "max_cpus (%u) should be multiple of threads (%u) ",
+                         max_cpus, smp_threads);
+            return 1;
+        }
+        return 0;
+}


If you decide to repost - here is incorrect indent.


+
  static void machine_class_init(ObjectClass *oc, void *data)
  {
      MachineClass *mc = MACHINE_CLASS(oc);
@@ -343,6 +362,7 @@ static void machine_class_init(ObjectClass *oc, void *data)
      /* Default 128 MB as guest ram size */
      mc->default_ram_size = 128 * M_BYTE;
      mc->rom_file_has_mr = true;
+    mc->validate_smp_config = validate_smp_config_generic;
  }

  static void machine_class_base_init(ObjectClass *oc, void *data)
diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
index 438cdae..dd4bba1 100644
--- a/hw/i386/pc_piix.c
+++ b/hw/i386/pc_piix.c
@@ -397,6 +397,12 @@ static void pc_xen_hvm_init(MachineState *machine)
  }
  #endif

+static int pc_validate_smp_config_default(int smp_cpus, int max_cpus,
+                                          int smp_threads)
+{
+    return 0;
+}
+
  #define DEFINE_I440FX_MACHINE(suffix, name, compatfn, optionfn) \
      static void pc_init_##suffix(MachineState *machine) \
      { \
@@ -434,6 +440,7 @@ static void pc_i440fx_2_5_machine_options(MachineClass *m)
      pc_i440fx_2_6_machine_options(m);
      m->alias = NULL;
      m->is_default = 0;
+    m->validate_smp_config = pc_validate_smp_config_default;
      SET_MACHINE_COMPAT(m, PC_COMPAT_2_5);
  }

diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
index 412b3cd..80ce9e8 100644
--- a/hw/i386/pc_q35.c
+++ b/hw/i386/pc_q35.c
@@ -325,6 +325,12 @@ static void pc_compat_1_4(MachineState *machine)
      pc_compat_1_5(machine);
  }

+static int pc_q35_validate_smp_config_default(int smp_cpus, int max_cpus,
+                                              int smp_threads)
+{
+    return 0;
+}
+
  #define DEFINE_Q35_MACHINE(suffix, name, compatfn, optionfn) \
      static void pc_init_##suffix(MachineState *machine) \
      { \
@@ -362,6 +368,7 @@ static void pc_q35_2_5_machine_options(MachineClass *m)
  {
      pc_q35_2_6_machine_options(m);
      m->alias = NULL;
+    m->validate_smp_config = pc_q35_validate_smp_config_default;
      SET_MACHINE_COMPAT(m, PC_COMPAT_2_5);
  }

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 414e0f9b..a330169 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -2320,6 +2320,12 @@ static const TypeInfo spapr_machine_info = {
      },
  };

+static int spapr_validate_smp_config_default(int smp_cpus, int max_cpus,
+                                          int smp_threads)


and here.


+{
+    return 0;
+}
+
  #define DEFINE_SPAPR_MACHINE(suffix, verstr, latest)                 \
      static void spapr_machine_##suffix##_class_init(ObjectClass *oc, \
                                                      void *data)      \
@@ -2379,6 +2385,7 @@ static void spapr_machine_2_5_class_options(MachineClass 
*mc)
      spapr_machine_2_6_class_options(mc);
      smc->use_ohci_by_default = true;
      SET_MACHINE_COMPAT(mc, SPAPR_COMPAT_2_5);
+    mc->validate_smp_config = spapr_validate_smp_config_default;
  }

  DEFINE_SPAPR_MACHINE(2_5, "2.5", false);
diff --git a/include/hw/boards.h b/include/hw/boards.h
index 0f30959..39091bf 100644
--- a/include/hw/boards.h
+++ b/include/hw/boards.h
@@ -99,6 +99,7 @@ struct MachineClass {
      HotplugHandler *(*get_hotplug_handler)(MachineState *machine,
                                             DeviceState *dev);
      unsigned (*cpu_index_to_socket_id)(unsigned cpu_index);
+    int (*validate_smp_config)(int smp_cpus, int max_cpus, int smp_threads);
  };

  /**
diff --git a/vl.c b/vl.c
index 5aaea77..4b36a49 100644
--- a/vl.c
+++ b/vl.c
@@ -4132,6 +4132,10 @@ int main(int argc, char **argv, char **envp)

      smp_parse(qemu_opts_find(qemu_find_opts("smp-opts"), NULL));

+    if (machine_class->validate_smp_config(smp_cpus, max_cpus, smp_threads)) {
+        exit(1);
+    }
+
      machine_class->max_cpus = machine_class->max_cpus ?: 1; /* Default to UP 
*/
      if (max_cpus > machine_class->max_cpus) {
          error_report("Number of SMP CPUs requested (%d) exceeds max CPUs "



--
Alexey



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