[Qemu-devel] [PATCH v6 1/6] ppc: spapr: Handle "ibm, nmi-register" and "ibm, nmi-interlock" RTAS calls

[Aravinda Prasad]

This patch adds support in QEMU to handle "ibm,nmi-register"
and "ibm,nmi-interlock" RTAS calls.

The machine check notification address is saved when the
OS issues "ibm,nmi-register" RTAS call.

This patch also handles the case when multiple processors
experience machine check at or about the same time by
handling "ibm,nmi-interlock" call. In such cases, as per
PAPR, subsequent processors serialize waiting for the first
processor to issue the "ibm,nmi-interlock" call. The second
processor that also received a machine check error waits
till the first processor is done reading the error log.
The first processor issues "ibm,nmi-interlock" call
when the error log is consumed. This patch implements the
releasing part of the error-log while subsequent patch
(which builds error log) handles the locking part.

Signed-off-by: Aravinda Prasad <address@hidden>
---
 hw/ppc/spapr.c         |   25 +++++++++++++++++++++++++
 hw/ppc/spapr_rtas.c    |   36 ++++++++++++++++++++++++++++++++++++
 include/hw/ppc/spapr.h |   15 ++++++++++++++-
 3 files changed, 75 insertions(+), 1 deletion(-)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index b6a571b..a533fbe 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -1757,6 +1757,16 @@ static void spapr_machine_reset(void)
     first_ppc_cpu->env.gpr[5] = 0;
 
     spapr->cas_reboot = false;
+
+    spapr->mc_reset = 1;
+    spapr->mc_status = -1;
+    spapr->guest_machine_check_addr = -1;
+
+    /* Before destroying, signal vCPUs waiting on this condition */
+    qemu_cond_broadcast(&spapr->mc_delivery_cond);
+    /* It is safe to call destroy as broadcast unblocks all vCPUs */
+    qemu_cond_destroy(&spapr->mc_delivery_cond);
+    qemu_cond_init(&spapr->mc_delivery_cond);
 }
 
 static void spapr_create_nvram(sPAPRMachineState *spapr)
@@ -2047,6 +2057,16 @@ static const VMStateDescription vmstate_spapr_dtb = {
     },
 };
 
+static const VMStateDescription vmstate_spapr_guest_mc_addr = {
+    .name = "spapr_guest_mc_addr",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT64(guest_machine_check_addr, sPAPRMachineState),
+        VMSTATE_END_OF_LIST()
+    },
+};
+
 static const VMStateDescription vmstate_spapr = {
     .name = "spapr",
     .version_id = 3,
@@ -2077,6 +2097,7 @@ static const VMStateDescription vmstate_spapr = {
         &vmstate_spapr_irq_map,
         &vmstate_spapr_cap_nested_kvm_hv,
         &vmstate_spapr_dtb,
+        &vmstate_spapr_guest_mc_addr,
         NULL
     }
 };
@@ -3021,6 +3042,10 @@ static void spapr_machine_init(MachineState *machine)
 
         kvmppc_spapr_enable_inkernel_multitce();
     }
+
+    spapr->mc_status = -1;
+    spapr->mc_reset = 0;
+    qemu_cond_init(&spapr->mc_delivery_cond);
 }
 
 static int spapr_kvm_type(const char *vm_type)
diff --git a/hw/ppc/spapr_rtas.c b/hw/ppc/spapr_rtas.c
index 7a2cb78..0c2aa0d 100644
--- a/hw/ppc/spapr_rtas.c
+++ b/hw/ppc/spapr_rtas.c
@@ -348,6 +348,38 @@ static void rtas_get_power_level(PowerPCCPU *cpu, 
sPAPRMachineState *spapr,
     rtas_st(rets, 1, 100);
 }
 
+static void rtas_ibm_nmi_register(PowerPCCPU *cpu,
+                                  sPAPRMachineState *spapr,
+                                  uint32_t token, uint32_t nargs,
+                                  target_ulong args,
+                                  uint32_t nret, target_ulong rets)
+{
+    spapr->mc_reset = 0;
+    spapr->guest_machine_check_addr = rtas_ld(args, 1);
+    rtas_st(rets, 0, RTAS_OUT_SUCCESS);
+}
+
+static void rtas_ibm_nmi_interlock(PowerPCCPU *cpu,
+                                   sPAPRMachineState *spapr,
+                                   uint32_t token, uint32_t nargs,
+                                   target_ulong args,
+                                   uint32_t nret, target_ulong rets)
+{
+    if (!spapr->guest_machine_check_addr) {
+        /* NMI register not called */
+        rtas_st(rets, 0, RTAS_OUT_PARAM_ERROR);
+    } else {
+        /*
+         * VCPU issuing "ibm,nmi-interlock" is done with NMI handling,
+         * hence unset mc_status.
+         */
+        spapr->mc_status = -1;
+        qemu_cond_signal(&spapr->mc_delivery_cond);
+        rtas_st(rets, 0, RTAS_OUT_SUCCESS);
+    }
+}
+
+
 static struct rtas_call {
     const char *name;
     spapr_rtas_fn fn;
@@ -489,6 +521,10 @@ static void core_rtas_register_types(void)
                         rtas_set_power_level);
     spapr_rtas_register(RTAS_GET_POWER_LEVEL, "get-power-level",
                         rtas_get_power_level);
+    spapr_rtas_register(RTAS_IBM_NMI_REGISTER, "ibm,nmi-register",
+                        rtas_ibm_nmi_register);
+    spapr_rtas_register(RTAS_IBM_NMI_INTERLOCK, "ibm,nmi-interlock",
+                        rtas_ibm_nmi_interlock);
 }
 
 type_init(core_rtas_register_types)
diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
index 59073a7..452f904 100644
--- a/include/hw/ppc/spapr.h
+++ b/include/hw/ppc/spapr.h
@@ -176,6 +176,17 @@ struct sPAPRMachineState {
      * occurs during the unplug process. */
     QTAILQ_HEAD(, sPAPRDIMMState) pending_dimm_unplugs;
 
+    /* State related to "ibm,nmi-register" and "ibm,nmi-interlock" calls */
+    target_ulong guest_machine_check_addr;
+    /*
+     * mc_status is set to -1 if mc is not in progress, else is set to the CPU
+     * handling the mc.
+     */
+    int mc_status;
+    /* mc_reset is set to 1 if machine reset is in progress */
+    bool mc_reset;
+    QemuCond mc_delivery_cond;
+
     /*< public >*/
     char *kvm_type;
     char *host_model;
@@ -608,8 +619,10 @@ target_ulong spapr_hypercall(PowerPCCPU *cpu, target_ulong 
opcode,
 #define RTAS_IBM_CREATE_PE_DMA_WINDOW           (RTAS_TOKEN_BASE + 0x27)
 #define RTAS_IBM_REMOVE_PE_DMA_WINDOW           (RTAS_TOKEN_BASE + 0x28)
 #define RTAS_IBM_RESET_PE_DMA_WINDOW            (RTAS_TOKEN_BASE + 0x29)
+#define RTAS_IBM_NMI_REGISTER                   (RTAS_TOKEN_BASE + 0x2A)
+#define RTAS_IBM_NMI_INTERLOCK                  (RTAS_TOKEN_BASE + 0x2B)
 
-#define RTAS_TOKEN_MAX                          (RTAS_TOKEN_BASE + 0x2A)
+#define RTAS_TOKEN_MAX                          (RTAS_TOKEN_BASE + 0x2C)
 
 /* RTAS ibm,get-system-parameter token values */
 #define RTAS_SYSPARM_SPLPAR_CHARACTERISTICS      20