PPC: tell the guest about the time base frequency

Our guest systems need to know by how much the timebase increases every second,
so there usually is a "timebase-frequency" property in the cpu leaf of the
device tree.

This property is missing in OpenBIOS.

With qemu, Linux's fallback timebase speed and qemu's internal timebase speed
match up. With KVM, that is no longer true. The guest is running at the same
timebase speed as the host.

This leads to massive timing problems. On my test machine, a "sleep 2" takes
about 14 seconds with KVM enabled.

This patch exports the timebase frequency to OpenBIOS, so it can then put them
into the device tree.

Signed-off-by: Alexander Graf <[email protected]>
Signed-off-by: Michael S. Tsirkin <[email protected]>

diff --git a/hw/ppc.h b/hw/ppc.h
index b9a12a113357a5b95877ee50e9b48cc7b8dfd644..de13092ae4202a7da595187f5f8123f16b011e37 100644 (file)
--- a/hw/ppc.h
+++ b/hw/ppc.h
@@ -46,5 +46,6 @@ enum {
 #define FW_CFG_PPC_WIDTH       (FW_CFG_ARCH_LOCAL + 0x00)
 #define FW_CFG_PPC_HEIGHT      (FW_CFG_ARCH_LOCAL + 0x01)
 #define FW_CFG_PPC_DEPTH       (FW_CFG_ARCH_LOCAL + 0x02)
+#define FW_CFG_PPC_TBFREQ      (FW_CFG_ARCH_LOCAL + 0x03)
 
 #define PPC_SERIAL_MM_BAUDBASE 399193

diff --git a/hw/ppc_newworld.c b/hw/ppc_newworld.c
index e66bde4aa03c3d8269fba4678d09208c5d981097..49b5e046aec2e443387cb9c1411fe5e68fe0f8b7 100644 (file)
--- a/hw/ppc_newworld.c
+++ b/hw/ppc_newworld.c
@@ -64,6 +64,7 @@
 #include "loader.h"
 #include "elf.h"
 #include "kvm.h"
+#include "kvm_ppc.h"
 
 #define MAX_IDE_BUS 2
 #define VGA_BIOS_SIZE 65536
@@ -413,6 +414,14 @@ static void ppc_core99_init (ram_addr_t ram_size,
     fw_cfg_add_i16(fw_cfg, FW_CFG_PPC_HEIGHT, graphic_height);
     fw_cfg_add_i16(fw_cfg, FW_CFG_PPC_DEPTH, graphic_depth);
 
+    if (kvm_enabled()) {
+#ifdef CONFIG_KVM
+        fw_cfg_add_i32(fw_cfg, FW_CFG_PPC_TBFREQ, kvmppc_get_tbfreq());
+#endif
+    } else {
+        fw_cfg_add_i32(fw_cfg, FW_CFG_PPC_TBFREQ, get_ticks_per_sec());
+    }
+
     qemu_register_boot_set(fw_cfg_boot_set, fw_cfg);
 }
 

diff --git a/hw/ppc_oldworld.c b/hw/ppc_oldworld.c
index 7ccc6a14718c4e361d064a25e3ba3b44731c6c11..04a78358dddaf9cc5dfe258deea3f118ad4cd280 100644 (file)
--- a/hw/ppc_oldworld.c
+++ b/hw/ppc_oldworld.c
@@ -40,6 +40,7 @@
 #include "loader.h"
 #include "elf.h"
 #include "kvm.h"
+#include "kvm_ppc.h"
 
 #define MAX_IDE_BUS 2
 #define VGA_BIOS_SIZE 65536
@@ -401,6 +402,14 @@ static void ppc_heathrow_init (ram_addr_t ram_size,
     fw_cfg_add_i16(fw_cfg, FW_CFG_PPC_HEIGHT, graphic_height);
     fw_cfg_add_i16(fw_cfg, FW_CFG_PPC_DEPTH, graphic_depth);
 
+    if (kvm_enabled()) {
+#ifdef CONFIG_KVM
+        fw_cfg_add_i32(fw_cfg, FW_CFG_PPC_TBFREQ, kvmppc_get_tbfreq());
+#endif
+    } else {
+        fw_cfg_add_i32(fw_cfg, FW_CFG_PPC_TBFREQ, get_ticks_per_sec());
+    }
+
     qemu_register_boot_set(fw_cfg_boot_set, fw_cfg);
 }
 

diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c
index 0424a784225003ebea327e267bc57f1fa85f1745..9886b543f65f79398d2e1ebccb5f0340061690c0 100644 (file)
--- a/target-ppc/kvm.c
+++ b/target-ppc/kvm.c
@@ -252,3 +252,50 @@ int kvm_arch_handle_exit(CPUState *env, struct kvm_run *run)
     return ret;
 }
 
+static int read_cpuinfo(const char *field, char *value, int len)
+{
+    FILE *f;
+    int ret = -1;
+    int field_len = strlen(field);
+    char line[512];
+
+    f = fopen("/proc/cpuinfo", "r");
+    if (!f) {
+        return -1;
+    }
+
+    do {
+        if(!fgets(line, sizeof(line), f)) {
+            break;
+        }
+        if (!strncmp(line, field, field_len)) {
+            strncpy(value, line, len);
+            ret = 0;
+            break;
+        }
+    } while(*line);
+
+    fclose(f);
+
+    return ret;
+}
+
+uint32_t kvmppc_get_tbfreq(void)
+{
+    char line[512];
+    char *ns;
+    uint32_t retval = get_ticks_per_sec();
+
+    if (read_cpuinfo("timebase", line, sizeof(line))) {
+        return retval;
+    }
+
+    if (!(ns = strchr(line, ':'))) {
+        return retval;
+    }
+
+    ns++;
+
+    retval = atoi(ns);
+    return retval;
+}

diff --git a/target-ppc/kvm_ppc.h b/target-ppc/kvm_ppc.h
index 3792ef725142000d065871e745202d3904e66f5b..e8d66e88e494d5e61cd8e3e2565621176a9c4b2b 100644 (file)
--- a/target-ppc/kvm_ppc.h
+++ b/target-ppc/kvm_ppc.h
@@ -14,4 +14,6 @@ void kvmppc_fdt_update(void *fdt);
 int kvmppc_read_host_property(const char *node_path, const char *prop,
                                      void *val, size_t len);
 
+uint32_t kvmppc_get_tbfreq(void);
+
 #endif /* __KVM_PPC_H__ */