Re: [Qemu-devel] [PATCH v2] hw/acpi: Select an node with memory for mapping memory hole to

[Dou Liyang]

Hi Igor,

At 08/16/2017 05:18 PM, Igor Mammedov wrote:

On Wed, 16 Aug 2017 09:26:51 +0800
Dou Liyang <douly.f...@cn.fujitsu.com> wrote:

Currently, Using the fisrt node without memory on the machine makes
QEMU unhappy. With this example command line:
  ... \
  -m 1024M,slots=4,maxmem=32G \
  -numa node,nodeid=0 \
  -numa node,mem=1024M,nodeid=1 \
  -numa node,nodeid=2 \
  -numa node,nodeid=3 \
Guest reports "No NUMA configuration found" and the NUMA topology is
wrong.

This is because when QEMU builds ACPI SRAT, it regards node0 as the
default node to deal with the memory hole(640K-1M). this means the
node0 must have some memory(>1M), but, actually it can have no
memory.

Fix this problem by replace the node0 with the first node which has
memory on it. Add a new function for each node. Also do some cleanup.

It seems harmless but one never knows for sure,
could you test it with different guests including old windows (up to XP)/
linux (2.6 stable kernel) versions?

I have test it with the following guests:

windows 7.
linux 4.13-rc5.

will test it in linux (2.6 and 3.10 stable kernel).

Thanks,
        dou.

Signed-off-by: Dou Liyang <douly.f...@cn.fujitsu.com>
---
V2 --> V1:
  -Fix a coding style problem
Replace
    for (node = 0;
            node < pcms->numa_nodes && pcms->node_mem[node] == 0;
            node++);

with
    for (node = 0; node < pcms->numa_nodes; node++) {
       if (pcms->node_mem[node] != 0) {
            break;
         }

 hw/i386/acpi-build.c | 78 +++++++++++++++++++++++++++++++++-------------------
 1 file changed, 50 insertions(+), 28 deletions(-)

diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index 98dd424..f93d712 100644
--- a/hw/i386/acpi-build.c
+++ b/hw/i386/acpi-build.c
@@ -2318,15 +2318,43 @@ build_tpm2(GArray *table_data, BIOSLinker *linker)
                  (void *)tpm2_ptr, "TPM2", sizeof(*tpm2_ptr), 4, NULL, NULL);
 }

+static uint64_t
+build_srat_node_entry(GArray *table_data, PCMachineState *pcms,
+                                int i, uint64_t mem_base, uint64_t mem_len)
+{
+    AcpiSratMemoryAffinity *numamem;
+    uint64_t next_base;
+
+    next_base = mem_base + mem_len;
+
+    /* Cut out the ACPI_PCI hole */
+    if (mem_base <= pcms->below_4g_mem_size &&
+        next_base > pcms->below_4g_mem_size) {
+        mem_len -= next_base - pcms->below_4g_mem_size;
+        if (mem_len > 0) {
+            numamem = acpi_data_push(table_data, sizeof *numamem);
+            build_srat_memory(numamem, mem_base, mem_len, i,
+                              MEM_AFFINITY_ENABLED);
+        }
+        mem_base = 1ULL << 32;
+        mem_len = next_base - pcms->below_4g_mem_size;
+        next_base += (1ULL << 32) - pcms->below_4g_mem_size;
+    }
+    numamem = acpi_data_push(table_data, sizeof *numamem);
+    build_srat_memory(numamem, mem_base, mem_len, i,
+                      MEM_AFFINITY_ENABLED);
+    return next_base;
+}
+
 static void
 build_srat(GArray *table_data, BIOSLinker *linker, MachineState *machine)
 {
     AcpiSystemResourceAffinityTable *srat;
     AcpiSratMemoryAffinity *numamem;

-    int i;
+    int i, node;
     int srat_start, numa_start, slots;
-    uint64_t mem_len, mem_base, next_base;
+    uint64_t mem_len, mem_base;
     MachineClass *mc = MACHINE_GET_CLASS(machine);
     const CPUArchIdList *apic_ids = mc->possible_cpu_arch_ids(machine);
     PCMachineState *pcms = PC_MACHINE(machine);
@@ -2370,36 +2398,30 @@ build_srat(GArray *table_data, BIOSLinker *linker, 
MachineState *machine)
     /* the memory map is a bit tricky, it contains at least one hole
      * from 640k-1M and possibly another one from 3.5G-4G.
      */
-    next_base = 0;
+
     numa_start = table_data->len;

-    numamem = acpi_data_push(table_data, sizeof *numamem);
-    build_srat_memory(numamem, 0, 640 * 1024, 0, MEM_AFFINITY_ENABLED);
-    next_base = 1024 * 1024;
-    for (i = 1; i < pcms->numa_nodes + 1; ++i) {
-        mem_base = next_base;
-        mem_len = pcms->node_mem[i - 1];
-        if (i == 1) {
-            mem_len -= 1024 * 1024;
+    /* get the first node which has memory and map the hole from 640K-1M */
+    for (node = 0; node < pcms->numa_nodes; node++) {
+        if (pcms->node_mem[node] != 0) {
+            break;
         }
-        next_base = mem_base + mem_len;
-
-        /* Cut out the ACPI_PCI hole */
-        if (mem_base <= pcms->below_4g_mem_size &&
-            next_base > pcms->below_4g_mem_size) {
-            mem_len -= next_base - pcms->below_4g_mem_size;
-            if (mem_len > 0) {
-                numamem = acpi_data_push(table_data, sizeof *numamem);
-                build_srat_memory(numamem, mem_base, mem_len, i - 1,
-                                  MEM_AFFINITY_ENABLED);
-            }
-            mem_base = 1ULL << 32;
-            mem_len = next_base - pcms->below_4g_mem_size;
-            next_base += (1ULL << 32) - pcms->below_4g_mem_size;
+    }
+    numamem = acpi_data_push(table_data, sizeof *numamem);
+    build_srat_memory(numamem, 0, 640 * 1024, node, MEM_AFFINITY_ENABLED);
+
+    /* map the rest of memory from 1M */
+    mem_base = 1024 * 1024;
+    mem_len = pcms->node_mem[node] - mem_base;
+    mem_base = build_srat_node_entry(table_data, pcms, node,
+                                            mem_base, mem_len);
+
+    for (i = 0; i < pcms->numa_nodes; i++) {
+        if (i == node) {
+            continue;
         }
-        numamem = acpi_data_push(table_data, sizeof *numamem);
-        build_srat_memory(numamem, mem_base, mem_len, i - 1,
-                          MEM_AFFINITY_ENABLED);
+        mem_base = build_srat_node_entry(table_data, pcms, i,
+                                            mem_base, pcms->node_mem[i]);
     }
     slots = (table_data->len - numa_start) / sizeof *numamem;
     for (; slots < pcms->numa_nodes + 2; slots++) {