pc: align DIMM's address/size by backend's alignment value

Performance wise it's better to align GVA by the backend's
page size.

Also do not allow to create DIMM device with suboptimal
size (i.e. not aligned to backends page size) to aviod
memory loss.

Do above only for 2.2 and newer machine types to avoid
breaking working configs with 2.1 machine type.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 33928b90fd3f8dab3d8af63f77aec46f058d9cf4..021ec44768a7b53c733efc3755c4b8e6455c5cdc 100644 (file)
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -1564,6 +1564,10 @@ static void pc_dimm_plug(HotplugHandler *hotplug_dev,
         goto out;
     }
 
+    if (memory_region_get_alignment(mr) && pcms->enforce_aligned_dimm) {
+        align = memory_region_get_alignment(mr);
+    }
+
     addr = pc_dimm_get_free_addr(pcms->hotplug_memory_base,
                                  memory_region_size(&pcms->hotplug_memory),
                                  !addr ? NULL : &addr, align,
@@ -1732,6 +1736,13 @@ static void pc_machine_set_vmport(Object *obj, bool value, Error **errp)
     pcms->vmport = value;
 }
 
+static bool pc_machine_get_aligned_dimm(Object *obj, Error **errp)
+{
+    PCMachineState *pcms = PC_MACHINE(obj);
+
+    return pcms->enforce_aligned_dimm;
+}
+
 static void pc_machine_initfn(Object *obj)
 {
     PCMachineState *pcms = PC_MACHINE(obj);
@@ -1744,11 +1755,17 @@ static void pc_machine_initfn(Object *obj)
                         pc_machine_get_max_ram_below_4g,
                         pc_machine_set_max_ram_below_4g,
                         NULL, NULL, NULL);
+
     pcms->vmport = !xen_enabled();
     object_property_add_bool(obj, PC_MACHINE_VMPORT,
                              pc_machine_get_vmport,
                              pc_machine_set_vmport,
                              NULL);
+
+    pcms->enforce_aligned_dimm = true;
+    object_property_add_bool(obj, PC_MACHINE_ENFORCE_ALIGNED_DIMM,
+                             pc_machine_get_aligned_dimm,
+                             NULL, NULL);
 }
 
 static void pc_machine_class_init(ObjectClass *oc, void *data)

diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
index 7bb97a4923dd7e09303dd76cb47528607233088a..741dffd5f325e974cba60acd0bdc04c7b513d6ed 100644 (file)
--- a/hw/i386/pc_piix.c
+++ b/hw/i386/pc_piix.c
@@ -305,10 +305,12 @@ static void pc_init_pci(MachineState *machine)
 
 static void pc_compat_2_1(MachineState *machine)
 {
+    PCMachineState *pcms = PC_MACHINE(machine);
     smbios_uuid_encoded = false;
     x86_cpu_compat_set_features("coreduo", FEAT_1_ECX, CPUID_EXT_VMX, 0);
     x86_cpu_compat_set_features("core2duo", FEAT_1_ECX, CPUID_EXT_VMX, 0);
     x86_cpu_compat_kvm_no_autodisable(FEAT_8000_0001_ECX, CPUID_EXT3_SVM);
+    pcms->enforce_aligned_dimm = false;
 }
 
 static void pc_compat_2_0(MachineState *machine)

diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
index 598e679749c78f8f678e7c831c9e57f2b31ec0ee..e9ba1a273569717fa6fa06d0fe54907f3c2836a1 100644 (file)
--- a/hw/i386/pc_q35.c
+++ b/hw/i386/pc_q35.c
@@ -284,6 +284,9 @@ static void pc_q35_init(MachineState *machine)
 
 static void pc_compat_2_1(MachineState *machine)
 {
+    PCMachineState *pcms = PC_MACHINE(machine);
+
+    pcms->enforce_aligned_dimm = false;
     smbios_uuid_encoded = false;
     x86_cpu_compat_set_features("coreduo", FEAT_1_ECX, CPUID_EXT_VMX, 0);
     x86_cpu_compat_set_features("core2duo", FEAT_1_ECX, CPUID_EXT_VMX, 0);

diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
index 7c3731f1b0c0a2930096ad40071c75b7262b492c..9d85b89e4f04b81090088719549ab56d92ce9a17 100644 (file)
--- a/include/hw/i386/pc.h
+++ b/include/hw/i386/pc.h
@@ -24,6 +24,8 @@
  * address space begins.
  * @hotplug_memory: hotplug memory addess space container
  * @acpi_dev: link to ACPI PM device that performs ACPI hotplug handling
+ * @enforce_aligned_dimm: check that DIMM's address/size is aligned by
+ *                        backend's alignment value if provided
  */
 struct PCMachineState {
     /*< private >*/
@@ -38,12 +40,14 @@ struct PCMachineState {
 
     uint64_t max_ram_below_4g;
     bool vmport;
+    bool enforce_aligned_dimm;
 };
 
 #define PC_MACHINE_ACPI_DEVICE_PROP "acpi-device"
 #define PC_MACHINE_MEMHP_REGION_SIZE "hotplug-memory-region-size"
 #define PC_MACHINE_MAX_RAM_BELOW_4G "max-ram-below-4g"
 #define PC_MACHINE_VMPORT           "vmport"
+#define PC_MACHINE_ENFORCE_ALIGNED_DIMM "enforce-aligned-dimm"
 
 /**
  * PCMachineClass: