Hi,
This one introduces a -maxcpus setting, allowing the user to specify
the maximum number of vCPUs the system can have, as discussed with Gleb
earlier in the week.
Cheers,
Jes
Introduce -maxcpus flag to QEMU and pass the value to the BIOS through
FW_CFG.
Follow on patch will use it to determine the size of the MADT.
Signed-off-by: Jes Sorensen <jes@xxxxxxx>
---
hw/fw_cfg.c | 1 +
hw/fw_cfg.h | 1 +
kvm/bios/rombios32.c | 16 ++++++++++++++++
qemu-options.hx | 9 +++++++++
sysemu.h | 1 +
vl.c | 8 ++++++++
6 files changed, 36 insertions(+)
Index: qemu-kvm/hw/fw_cfg.c
===================================================================
--- qemu-kvm.orig/hw/fw_cfg.c
+++ qemu-kvm/hw/fw_cfg.c
@@ -279,6 +279,7 @@ void *fw_cfg_init(uint32_t ctl_port, uin
fw_cfg_add_bytes(s, FW_CFG_UUID, qemu_uuid, 16);
fw_cfg_add_i16(s, FW_CFG_NOGRAPHIC, (uint16_t)(display_type == DT_NOGRAPHIC));
fw_cfg_add_i16(s, FW_CFG_NB_CPUS, (uint16_t)smp_cpus);
+ fw_cfg_add_i16(s, FW_CFG_MAX_CPUS, (uint16_t)max_cpus);
register_savevm("fw_cfg", -1, 1, fw_cfg_save, fw_cfg_load, s);
qemu_register_reset(fw_cfg_reset, 0, s);
Index: qemu-kvm/hw/fw_cfg.h
===================================================================
--- qemu-kvm.orig/hw/fw_cfg.h
+++ qemu-kvm/hw/fw_cfg.h
@@ -15,6 +15,7 @@
#define FW_CFG_INITRD_SIZE 0x0b
#define FW_CFG_BOOT_DEVICE 0x0c
#define FW_CFG_NUMA 0x0d
+#define FW_CFG_MAX_CPUS 0x0e
#define FW_CFG_MAX_ENTRY 0x10
#define FW_CFG_WRITE_CHANNEL 0x4000
Index: qemu-kvm/kvm/bios/rombios32.c
===================================================================
--- qemu-kvm.orig/kvm/bios/rombios32.c
+++ qemu-kvm/kvm/bios/rombios32.c
@@ -441,6 +441,7 @@ void delay_ms(int n)
}
uint16_t smp_cpus;
+uint16_t max_cpus = MAX_CPUS;
uint32_t cpuid_signature;
uint32_t cpuid_features;
uint32_t cpuid_ext_features;
@@ -484,6 +485,7 @@ void wrmsr_smp(uint32_t index, uint64_t
#define QEMU_CFG_ID 0x01
#define QEMU_CFG_UUID 0x02
#define QEMU_CFG_NUMA 0x0D
+#define QEMU_CFG_MAX_CPUS 0x0E
#define QEMU_CFG_ARCH_LOCAL 0x8000
#define QEMU_CFG_ACPI_TABLES (QEMU_CFG_ARCH_LOCAL + 0)
#define QEMU_CFG_SMBIOS_ENTRIES (QEMU_CFG_ARCH_LOCAL + 1)
@@ -546,6 +548,19 @@ static uint16_t smbios_entries(void)
return cnt;
}
+static uint16_t get_max_cpus(void)
+{
+ uint16_t cnt;
+
+ qemu_cfg_select(QEMU_CFG_MAX_CPUS);
+ qemu_cfg_read((uint8_t*)&cnt, sizeof(cnt));
+
+ if (!cnt)
+ cnt = MAX_CPUS;
+
+ return cnt;
+}
+
uint64_t qemu_cfg_get64 (void)
{
uint64_t ret;
@@ -1655,6 +1670,7 @@ void acpi_bios_init(void)
addr += sizeof(SSDTCode);
#ifdef BX_QEMU
+ max_cpus = get_max_cpus();
qemu_cfg_select(QEMU_CFG_NUMA);
nb_numa_nodes = qemu_cfg_get64();
#else
Index: qemu-kvm/qemu-options.hx
===================================================================
--- qemu-kvm.orig/qemu-options.hx
+++ qemu-kvm/qemu-options.hx
@@ -47,6 +47,15 @@ CPUs are supported. On Sparc32 target, L
to 4.
ETEXI
+DEF("maxcpus", HAS_ARG, QEMU_OPTION_maxcpus,
+ "-maxcpus n set maximumthe number of possibly CPUs to 'n'\n")
+STEXI
+@item -maxcpus @var{n}
+Set the maximum number of possible CPUs to @var(n). @var(n) has to be
+bigger or equal to the value of -smp. If @var(n) is equal to -smp,
+there will be no space for hotplug cpus to be added later.
+ETEXI
+
DEF("numa", HAS_ARG, QEMU_OPTION_numa,
"-numa node[,mem=size][,cpus=cpu[-cpu]][,nodeid=node]\n")
STEXI
Index: qemu-kvm/sysemu.h
===================================================================
--- qemu-kvm.orig/sysemu.h
+++ qemu-kvm/sysemu.h
@@ -119,6 +119,7 @@ extern int alt_grab;
extern int usb_enabled;
extern int no_virtio_balloon;
extern int smp_cpus;
+extern int max_cpus;
extern int cursor_hide;
extern int graphic_rotate;
extern int no_quit;
Index: qemu-kvm/vl.c
===================================================================
--- qemu-kvm.orig/vl.c
+++ qemu-kvm/vl.c
@@ -246,6 +246,7 @@ int singlestep = 0;
const char *assigned_devices[MAX_DEV_ASSIGN_CMDLINE];
int assigned_devices_index;
int smp_cpus = 1;
+int max_cpus = 16;
const char *vnc_display;
int acpi_enabled = 1;
int no_hpet = 0;
@@ -5666,6 +5667,13 @@ int main(int argc, char **argv, char **e
exit(1);
}
break;
+ case QEMU_OPTION_maxcpus:
+ max_cpus = atoi(optarg);
+ if ((max_cpus < 1) || (max_cpus > machine->max_cpus)) {
+ fprintf(stderr, "Invalid number of CPUs\n");
+ exit(1);
+ }
+ break;
case QEMU_OPTION_vnc:
display_type = DT_VNC;
vnc_display = optarg;
