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Re: [Qemu-arm] [Qemu-devel] [PATCH] arm: virt-acpi: each MADT.GICC entry

From: Shannon Zhao
Subject: Re: [Qemu-arm] [Qemu-devel] [PATCH] arm: virt-acpi: each MADT.GICC entry as enabled unconditionally
Date: Fri, 29 Jan 2016 22:59:32 +0800
User-agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0

On 2016/1/29 22:24, Igor Mammedov wrote:
in current impl. condition

build_madt() {
   if (test_bit(i, cpuinfo->found_cpus))

is always true since loop handles only present CPUs
in range [0..smp_cpus).
But to fill usless cpuinfo->found_cpus we do unnecessary
scan over QOM tree to find the same CPUs.
So mark GICC as present always and drop not needed
code that fills cpuinfo->found_cpus.

Signed-off-by: Igor Mammedov<address@hidden>
It's just simple cleanup but I'm trying to generalize
a bit CPU related ACPI tables and as part of it get rid
of found_cpus bitmap and if possible cpu_index usage
in ACPI parts of code.
  hw/arm/virt-acpi-build.c | 26 +++-----------------------
  1 file changed, 3 insertions(+), 23 deletions(-)

diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c
index 87fbe7c..3ed39fc 100644
--- a/hw/arm/virt-acpi-build.c
+++ b/hw/arm/virt-acpi-build.c
@@ -46,20 +46,6 @@
  #define ARM_SPI_BASE 32

-typedef struct VirtAcpiCpuInfo {
-} VirtAcpiCpuInfo;
-static void virt_acpi_get_cpu_info(VirtAcpiCpuInfo *cpuinfo)
-    CPUState *cpu;
-    memset(cpuinfo->found_cpus, 0, sizeof cpuinfo->found_cpus);
-    CPU_FOREACH(cpu) {
-        set_bit(cpu->cpu_index, cpuinfo->found_cpus);
-    }
  static void acpi_dsdt_add_cpus(Aml *scope, int smp_cpus)
      uint16_t i;
@@ -458,8 +444,7 @@ build_gtdt(GArray *table_data, GArray *linker)

  /* MADT */
  static void
-build_madt(GArray *table_data, GArray *linker, VirtGuestInfo *guest_info,
-           VirtAcpiCpuInfo *cpuinfo)
+build_madt(GArray *table_data, GArray *linker, VirtGuestInfo *guest_info)
      int madt_start = table_data->len;
      const MemMapEntry *memmap = guest_info->memmap;
@@ -489,9 +474,7 @@ build_madt(GArray *table_data, GArray *linker, 
VirtGuestInfo *guest_info,
          gicc->cpu_interface_number = i;
          gicc->arm_mpidr = armcpu->mp_affinity;
          gicc->uid = i;
-        if (test_bit(i, cpuinfo->found_cpus)) {
-            gicc->flags = cpu_to_le32(ACPI_GICC_ENABLED);
-        }
+        gicc->flags = cpu_to_le32(ACPI_GICC_ENABLED);
Ah, yes, it uses smp_cpus not max_cpus. But we still needs to support max_cpus usage even though it doesn't support vcpu hotplug currently. So we may need to introduce guest_info->max_cpus and use it here. And below check in virt.c is not right while it should compare the global max_cpus with the max_cpus GIC supports.

    if (smp_cpus > max_cpus) {
        error_report("Number of SMP CPUs requested (%d) exceeds max CPUs "
                     "supported by machine 'mach-virt' (%d)",
                     smp_cpus, max_cpus);


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