[Qemu-devel] [PATCH 17/27] Implement assorted pSeries hcalls and RTAS methods

[David Gibson]

This patch adds several small utility hypercalls and RTAS methods to
the pSeries platform emulation.  Specifically:

* 'display-character' rtas call

This just prints a character to the console, it's occasionally used
for early debug of the OS.  The support includes a hack to make this
RTAS call respond on the normal token value present on real hardware,
since some early debugging tools just assume this value without
checking the device tree.

* 'get-time-of-day' rtas call

This one just takes the host real time, converts to the PAPR described
format and returns it to the guest.

* 'power-off' rtas call

This one shuts down the emulated system.

* H_DABR hypercall

On pSeries, the DABR debug register is usually a hypervisor resource
and virtualized through this hypercall.  If the hypercall is not
present, Linux will under some circumstances attempt to manipulate the
DABR directly which will fail on this emulated machine.

This stub implementation is enough to stop that behaviour, although it
doesn't actually implement the requested DABR operations as yet.

Signed-off-by: Paul Mackerras <address@hidden>
Signed-off-by: David Gibson <address@hidden>
---
 hw/spapr.c       |    2 +-
 hw/spapr_hcall.c |   10 ++++++++
 hw/spapr_rtas.c  |   69 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 80 insertions(+), 1 deletions(-)

diff --git a/hw/spapr.c b/hw/spapr.c
index c07af19..6c64de8 100644
--- a/hw/spapr.c
+++ b/hw/spapr.c
@@ -63,7 +63,7 @@ static void *spapr_create_fdt(int *fdt_size, ram_addr_t 
ramsize,
     uint32_t start_prop = cpu_to_be32(initrd_base);
     uint32_t end_prop = cpu_to_be32(initrd_base + initrd_size);
     uint32_t pft_size_prop[] = {0, cpu_to_be32(hash_shift)};
-    char hypertas_prop[] = "hcall-pft\0hcall-term";
+    char hypertas_prop[] = "hcall-pft\0hcall-term\0hcall-dabr";
     int i;
     char *modelname;
     int ret;
diff --git a/hw/spapr_hcall.c b/hw/spapr_hcall.c
index d8c721e..a47a97b 100644
--- a/hw/spapr_hcall.c
+++ b/hw/spapr_hcall.c
@@ -248,6 +248,13 @@ static target_ulong h_protect(CPUState *env, 
sPAPREnvironment *spapr,
     return H_SUCCESS;
 }
 
+static target_ulong h_set_dabr(CPUState *env, sPAPREnvironment *spapr,
+                               target_ulong opcode, target_ulong *args)
+{
+    /* FIXME: actually implement this */
+    return H_HARDWARE;
+}
+
 static target_ulong h_rtas(CPUState *env, sPAPREnvironment *spapr,
                            target_ulong opcode, target_ulong *args)
 {
@@ -317,6 +324,9 @@ static void hypercall_init(void)
     spapr_register_hypercall(H_REMOVE, h_remove);
     spapr_register_hypercall(H_PROTECT, h_protect);
 
+    /* hcall-dabr */
+    spapr_register_hypercall(H_SET_DABR, h_set_dabr);
+
     /* qemu/KVM-PPC specific hcalls */
     spapr_register_hypercall(KVMPPC_H_RTAS, h_rtas);
 }
diff --git a/hw/spapr_rtas.c b/hw/spapr_rtas.c
index 3f090f5..7226853 100644
--- a/hw/spapr_rtas.c
+++ b/hw/spapr_rtas.c
@@ -38,6 +38,58 @@
 #define TOKEN_BASE      0x2000
 #define TOKEN_MAX       0x100
 
+static void rtas_display_character(sPAPREnvironment *spapr,
+                                   uint32_t token, uint32_t nargs,
+                                   target_ulong args,
+                                   uint32_t nret, target_ulong rets)
+{
+    uint8_t c = rtas_ld(args, 0);
+    VIOsPAPRDevice *sdev = spapr_vio_find_by_reg(spapr->vio_bus, 0);
+
+    if (!sdev) {
+        rtas_st(rets, 0, -1);
+    } else {
+        vty_putchars(sdev, &c, sizeof(c));
+        rtas_st(rets, 0, 0);
+    }
+}
+
+static void rtas_get_time_of_day(sPAPREnvironment *spapr,
+                                 uint32_t token, uint32_t nargs,
+                                 target_ulong args,
+                                 uint32_t nret, target_ulong rets)
+{
+    struct tm tm;
+
+    if (nret != 8) {
+        rtas_st(rets, 0, -3);
+        return;
+    }
+
+    qemu_get_timedate(&tm, 0);
+
+    rtas_st(rets, 0, 0); /* Success */
+    rtas_st(rets, 1, tm.tm_year + 1900);
+    rtas_st(rets, 2, tm.tm_mon + 1);
+    rtas_st(rets, 3, tm.tm_mday);
+    rtas_st(rets, 4, tm.tm_hour);
+    rtas_st(rets, 5, tm.tm_min);
+    rtas_st(rets, 6, tm.tm_sec);
+    rtas_st(rets, 7, 0); /* we don't do nanoseconds */
+}
+
+static void rtas_power_off(sPAPREnvironment *spapr,
+                           uint32_t token, uint32_t nargs, target_ulong args,
+                           uint32_t nret, target_ulong rets)
+{
+    if (nargs != 2 || nret != 1) {
+        rtas_st(rets, 0, -3);
+        return;
+    }
+    qemu_system_shutdown_request();
+    rtas_st(rets, 0, 0);
+}
+
 static struct rtas_call {
     const char *name;
     spapr_rtas_fn fn;
@@ -59,6 +111,15 @@ target_ulong spapr_rtas_call(sPAPREnvironment *spapr,
         }
     }
 
+    /* HACK: Some Linux early debug code uses RTAS display-character,
+     * but assumes the token value is 0xa (which it is on some real
+     * machines) without looking it up in the device tree.  This
+     * special case makes this work */
+    if (token == 0xa) {
+        rtas_display_character(spapr, 0xa, nargs, args, nret, rets);
+        return H_SUCCESS;
+    }
+
     hcall_dprintf("Unknown RTAS token 0x%x\n", token);
     rtas_st(rets, 0, -3);
     return H_PARAMETER;
@@ -129,3 +190,11 @@ int spapr_rtas_device_tree_setup(void *fdt, 
target_phys_addr_t rtas_addr,
     }
     return 0;
 }
+
+static void register_core_rtas(void)
+{
+    spapr_rtas_register("display-character", rtas_display_character);
+    spapr_rtas_register("get-time-of-day", rtas_get_time_of_day);
+    spapr_rtas_register("power-off", rtas_power_off);
+}
+device_init(register_core_rtas);
-- 
1.7.1