[Qemu-devel] [PATCH] spapr: add "compat" machine option

[Alexey Kardashevskiy]

To be able to boot on newer hardware that the software support,
PowerISA defines a logical PVR, one per every PowerISA specification
version from 2.04.

This adds the "compat" option which takes values 205 or 206 and forces
QEMU to boot the guest with a logical PVR (CPU_POWERPC_LOGICAL_2_05 or
CPU_POWERPC_LOGICAL_2_06).

The guest reads the logical PVR value from "cpu-version" property of
a CPU device node.

Cc: Nikunj A Dadhania <address@hidden>
Cc: Andreas Färber <address@hidden>
Signed-off-by: Alexey Kardashevskiy <address@hidden>
---
 hw/ppc/spapr.c          | 40 ++++++++++++++++++++++++++++++++++++++++
 include/hw/ppc/spapr.h  |  2 ++
 target-ppc/cpu-models.h | 10 ++++++++++
 target-ppc/cpu.h        |  3 +++
 target-ppc/kvm.c        |  2 ++
 vl.c                    |  4 ++++
 6 files changed, 61 insertions(+)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index a09a1d9..737452d 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -33,6 +33,7 @@
 #include "sysemu/kvm.h"
 #include "kvm_ppc.h"
 #include "mmu-hash64.h"
+#include "cpu-models.h"
 
 #include "hw/boards.h"
 #include "hw/ppc/ppc.h"
@@ -196,6 +197,26 @@ static XICSState *xics_system_init(int nr_servers, int 
nr_irqs)
     return icp;
 }
 
+static void spapr_compat_mode_init(sPAPREnvironment *spapr)
+{
+    QemuOpts *machine_opts = qemu_get_machine_opts();
+    uint64_t compat = qemu_opt_get_number(machine_opts, "compat", 0);
+
+    switch (compat) {
+    case 0:
+        break;
+    case 205:
+        spapr->arch_compat = CPU_POWERPC_LOGICAL_2_05;
+        break;
+    case 206:
+        spapr->arch_compat = CPU_POWERPC_LOGICAL_2_06;
+        break;
+    default:
+        perror("Unsupported mode, only are 205, 206 supported\n");
+        break;
+    }
+}
+
 static int spapr_fixup_cpu_dt(void *fdt, sPAPREnvironment *spapr)
 {
     int ret = 0, offset;
@@ -206,6 +227,7 @@ static int spapr_fixup_cpu_dt(void *fdt, sPAPREnvironment 
*spapr)
 
     CPU_FOREACH(cpu) {
         DeviceClass *dc = DEVICE_GET_CLASS(cpu);
+        CPUPPCState *env = &(POWERPC_CPU(cpu)->env);
         uint32_t associativity[] = {cpu_to_be32(0x5),
                                     cpu_to_be32(0x0),
                                     cpu_to_be32(0x0),
@@ -238,6 +260,14 @@ static int spapr_fixup_cpu_dt(void *fdt, sPAPREnvironment 
*spapr)
         if (ret < 0) {
             return ret;
         }
+
+        if (env->arch_compat) {
+            ret = fdt_setprop(fdt, offset, "cpu-version",
+                              &env->arch_compat, sizeof(env->arch_compat));
+            if (ret < 0) {
+                return ret;
+            }
+        }
     }
     return ret;
 }
@@ -1145,6 +1175,8 @@ static void ppc_spapr_init(QEMUMachineInitArgs *args)
     spapr = g_malloc0(sizeof(*spapr));
     QLIST_INIT(&spapr->phbs);
 
+    spapr_compat_mode_init(spapr);
+
     cpu_ppc_hypercall = emulate_spapr_hypercall;
 
     /* Allocate RMA if necessary */
@@ -1226,6 +1258,14 @@ static void ppc_spapr_init(QEMUMachineInitArgs *args)
 
         xics_cpu_setup(spapr->icp, cpu);
 
+        /*
+         * If compat mode is set in the command line, pass it to CPU so KVM
+         * will be able to set it in the host kernel.
+         */
+        if (spapr->arch_compat) {
+            env->arch_compat = spapr->arch_compat;
+        }
+
         qemu_register_reset(spapr_cpu_reset, cpu);
     }
 
diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
index ca175b0..201c578 100644
--- a/include/hw/ppc/spapr.h
+++ b/include/hw/ppc/spapr.h
@@ -34,6 +34,8 @@ typedef struct sPAPREnvironment {
     uint32_t epow_irq;
     Notifier epow_notifier;
 
+    uint32_t arch_compat;        /* Compatible PVR from the command line */
+
     /* Migration state */
     int htab_save_index;
     bool htab_first_pass;
diff --git a/target-ppc/cpu-models.h b/target-ppc/cpu-models.h
index 49ba4a4..d7c033c 100644
--- a/target-ppc/cpu-models.h
+++ b/target-ppc/cpu-models.h
@@ -583,6 +583,16 @@ enum {
     CPU_POWERPC_RS64II             = 0x00340000,
     CPU_POWERPC_RS64III            = 0x00360000,
     CPU_POWERPC_RS64IV             = 0x00370000,
+
+    /* Logical CPUs */
+    CPU_POWERPC_LOGICAL_MASK       = 0xFFFFFFFF,
+    CPU_POWERPC_LOGICAL_2_04       = 0x0F000001,
+    CPU_POWERPC_LOGICAL_2_05       = 0x0F000002,
+    CPU_POWERPC_LOGICAL_2_06       = 0x0F000003,
+    CPU_POWERPC_LOGICAL_2_06_PLUS  = 0x0F100003,
+    CPU_POWERPC_LOGICAL_2_07       = 0x0F000004,
+    CPU_POWERPC_LOGICAL_2_08       = 0x0F000005,
+
 #endif /* defined(TARGET_PPC64) */
     /* Original POWER */
     /* XXX: should be POWER (RIOS), RSC3308, RSC4608,
diff --git a/target-ppc/cpu.h b/target-ppc/cpu.h
index 422a6bb..fc837c1 100644
--- a/target-ppc/cpu.h
+++ b/target-ppc/cpu.h
@@ -999,6 +999,9 @@ struct CPUPPCState {
     /* Device control registers */
     ppc_dcr_t *dcr_env;
 
+    /* Architecture compatibility mode */
+    uint32_t arch_compat;
+
     int dcache_line_size;
     int icache_line_size;
 
diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c
index 4bc4496..7b853a3 100644
--- a/target-ppc/kvm.c
+++ b/target-ppc/kvm.c
@@ -872,6 +872,7 @@ int kvm_arch_put_registers(CPUState *cs, int level)
                 DPRINTF("Warning: Unable to set VPA information to KVM\n");
             }
         }
+        kvm_set_one_reg(cs, KVM_REG_PPC_ARCH_COMPAT, &env->arch_compat);
 #endif /* TARGET_PPC64 */
     }
 
@@ -1083,6 +1084,7 @@ int kvm_arch_get_registers(CPUState *cs)
                 DPRINTF("Warning: Unable to get VPA information from KVM\n");
             }
         }
+        kvm_get_one_reg(cs, KVM_REG_PPC_ARCH_COMPAT, &env->arch_compat);
 #endif
     }
 
diff --git a/vl.c b/vl.c
index 4e709d5..90dad7b 100644
--- a/vl.c
+++ b/vl.c
@@ -427,6 +427,10 @@ static QemuOptsList qemu_machine_opts = {
             .name = "usb",
             .type = QEMU_OPT_BOOL,
             .help = "Set on/off to enable/disable usb",
+        }, {
+            .name = "compat",
+            .type = QEMU_OPT_NUMBER,
+            .help = "Selects compatibility mode on CPU",
         },
         { /* End of list */ }
     },
-- 
1.8.4.rc4