diff --git a/audio/audio.c b/audio/audio.c
index 9ac9a20..7a9e680 100644
--- a/audio/audio.c
+++ b/audio/audio.c
@@ -1491,16 +1491,14 @@
 
 size_t audio_generic_read(HWVoiceIn *hw, void *buf, size_t size)
 {
-    size_t src_size, copy_size;
-    void *src = hw->pcm_ops->get_buffer_in(hw, &src_size);
-    copy_size = MIN(size, src_size);
+    void *src = hw->pcm_ops->get_buffer_in(hw, &size);
 
-    memcpy(buf, src, copy_size);
-    hw->pcm_ops->put_buffer_in(hw, src, copy_size);
-    return copy_size;
+    memcpy(buf, src, size);
+    hw->pcm_ops->put_buffer_in(hw, src, size);
+
+    return size;
 }
 
-
 static int audio_driver_init(AudioState *s, struct audio_driver *drv,
                              bool msg, Audiodev *dev)
 {
diff --git a/audio/dsoundaudio.c b/audio/dsoundaudio.c
index bd57082..4cdf19a 100644
--- a/audio/dsoundaudio.c
+++ b/audio/dsoundaudio.c
@@ -279,7 +279,7 @@
         return -1;
     }
 
-    if (*statusp & DSERR_BUFFERLOST) {
+    if (*statusp & DSBSTATUS_BUFFERLOST) {
         dsound_restore_out(dsb, s);
         return -1;
     }
@@ -540,7 +540,12 @@
     }
 
     req_size = audio_ring_dist(cpos, hw->pos_emul, hw->size_emul);
-    req_size = MIN(req_size, hw->size_emul - hw->pos_emul);
+    req_size = MIN(*size, MIN(req_size, hw->size_emul - hw->pos_emul));
+
+    if (req_size == 0) {
+        *size = 0;
+        return NULL;
+    }
 
     err = dsound_lock_in(dscb, &hw->info, hw->pos_emul, req_size, &ret, NULL,
                          &act_size, NULL, false, ds->s);
diff --git a/hw/display/ati_2d.c b/hw/display/ati_2d.c
index 42e8231..23a8ae0 100644
--- a/hw/display/ati_2d.c
+++ b/hw/display/ati_2d.c
@@ -53,12 +53,20 @@
             s->vga.vbe_start_addr, surface_data(ds), surface_stride(ds),
             surface_bits_per_pixel(ds),
             (s->regs.dp_mix & GMC_ROP3_MASK) >> 16);
-    int dst_x = (s->regs.dp_cntl & DST_X_LEFT_TO_RIGHT ?
-                 s->regs.dst_x : s->regs.dst_x + 1 - s->regs.dst_width);
-    int dst_y = (s->regs.dp_cntl & DST_Y_TOP_TO_BOTTOM ?
-                 s->regs.dst_y : s->regs.dst_y + 1 - s->regs.dst_height);
+    unsigned dst_x = (s->regs.dp_cntl & DST_X_LEFT_TO_RIGHT ?
+                      s->regs.dst_x : s->regs.dst_x + 1 - s->regs.dst_width);
+    unsigned dst_y = (s->regs.dp_cntl & DST_Y_TOP_TO_BOTTOM ?
+                      s->regs.dst_y : s->regs.dst_y + 1 - s->regs.dst_height);
     int bpp = ati_bpp_from_datatype(s);
+    if (!bpp) {
+        qemu_log_mask(LOG_GUEST_ERROR, "Invalid bpp\n");
+        return;
+    }
     int dst_stride = DEFAULT_CNTL ? s->regs.dst_pitch : s->regs.default_pitch;
+    if (!dst_stride) {
+        qemu_log_mask(LOG_GUEST_ERROR, "Zero dest pitch\n");
+        return;
+    }
     uint8_t *dst_bits = s->vga.vram_ptr + (DEFAULT_CNTL ?
                         s->regs.dst_offset : s->regs.default_offset);
 
@@ -82,12 +90,16 @@
     switch (s->regs.dp_mix & GMC_ROP3_MASK) {
     case ROP3_SRCCOPY:
     {
-        int src_x = (s->regs.dp_cntl & DST_X_LEFT_TO_RIGHT ?
-                     s->regs.src_x : s->regs.src_x + 1 - s->regs.dst_width);
-        int src_y = (s->regs.dp_cntl & DST_Y_TOP_TO_BOTTOM ?
-                     s->regs.src_y : s->regs.src_y + 1 - s->regs.dst_height);
+        unsigned src_x = (s->regs.dp_cntl & DST_X_LEFT_TO_RIGHT ?
+                       s->regs.src_x : s->regs.src_x + 1 - s->regs.dst_width);
+        unsigned src_y = (s->regs.dp_cntl & DST_Y_TOP_TO_BOTTOM ?
+                       s->regs.src_y : s->regs.src_y + 1 - s->regs.dst_height);
         int src_stride = DEFAULT_CNTL ?
                          s->regs.src_pitch : s->regs.default_pitch;
+        if (!src_stride) {
+            qemu_log_mask(LOG_GUEST_ERROR, "Zero source pitch\n");
+            return;
+        }
         uint8_t *src_bits = s->vga.vram_ptr + (DEFAULT_CNTL ?
                             s->regs.src_offset : s->regs.default_offset);
 
@@ -137,8 +149,10 @@
                                     dst_y * surface_stride(ds),
                                     s->regs.dst_height * surface_stride(ds));
         }
-        s->regs.dst_x += s->regs.dst_width;
-        s->regs.dst_y += s->regs.dst_height;
+        s->regs.dst_x = (s->regs.dp_cntl & DST_X_LEFT_TO_RIGHT ?
+                         dst_x + s->regs.dst_width : dst_x);
+        s->regs.dst_y = (s->regs.dp_cntl & DST_Y_TOP_TO_BOTTOM ?
+                         dst_y + s->regs.dst_height : dst_y);
         break;
     }
     case ROP3_PATCOPY:
@@ -179,7 +193,8 @@
                                     dst_y * surface_stride(ds),
                                     s->regs.dst_height * surface_stride(ds));
         }
-        s->regs.dst_y += s->regs.dst_height;
+        s->regs.dst_y = (s->regs.dp_cntl & DST_Y_TOP_TO_BOTTOM ?
+                         dst_y + s->regs.dst_height : dst_y);
         break;
     }
     default:
diff --git a/hw/ppc/e500.c b/hw/ppc/e500.c
index 854cd3a..0d1f411 100644
--- a/hw/ppc/e500.c
+++ b/hw/ppc/e500.c
@@ -1047,6 +1047,10 @@
     }
 
     filename = qemu_find_file(QEMU_FILE_TYPE_BIOS, payload_name);
+    if (!filename) {
+        error_report("could not find firmware/kernel file '%s'", payload_name);
+        exit(1);
+    }
 
     payload_size = load_elf(filename, NULL, NULL, NULL,
                             &bios_entry, &loadaddr, NULL, NULL,
diff --git a/hw/ppc/pnv.c b/hw/ppc/pnv.c
index b75ad06..c9cb6fa 100644
--- a/hw/ppc/pnv.c
+++ b/hw/ppc/pnv.c
@@ -571,10 +571,29 @@
 
 static void pnv_reset(MachineState *machine)
 {
+    PnvMachineState *pnv = PNV_MACHINE(machine);
+    IPMIBmc *bmc;
     void *fdt;
 
     qemu_devices_reset();
 
+    /*
+     * The machine should provide by default an internal BMC simulator.
+     * If not, try to use the BMC device that was provided on the command
+     * line.
+     */
+    bmc = pnv_bmc_find(&error_fatal);
+    if (!pnv->bmc) {
+        if (!bmc) {
+            warn_report("machine has no BMC device. Use '-device "
+                        "ipmi-bmc-sim,id=bmc0 -device isa-ipmi-bt,bmc=bmc0,irq=10' "
+                        "to define one");
+        } else {
+            pnv_bmc_set_pnor(bmc, pnv->pnor);
+            pnv->bmc = bmc;
+        }
+    }
+
     fdt = pnv_dt_create(machine);
 
     /* Pack resulting tree */
@@ -833,9 +852,6 @@
     }
     g_free(chip_typename);
 
-    /* Create the machine BMC simulator */
-    pnv->bmc = pnv_bmc_create(pnv->pnor);
-
     /* Instantiate ISA bus on chip 0 */
     pnv->isa_bus = pnv_isa_create(pnv->chips[0], &error_fatal);
 
@@ -845,8 +861,14 @@
     /* Create an RTC ISA device too */
     mc146818_rtc_init(pnv->isa_bus, 2000, NULL);
 
-    /* Create the IPMI BT device for communication with the BMC */
-    pnv_ipmi_bt_init(pnv->isa_bus, pnv->bmc, 10);
+    /*
+     * Create the machine BMC simulator and the IPMI BT device for
+     * communication with the BMC
+     */
+    if (defaults_enabled()) {
+        pnv->bmc = pnv_bmc_create(pnv->pnor);
+        pnv_ipmi_bt_init(pnv->isa_bus, pnv->bmc, 10);
+    }
 
     /*
      * OpenPOWER systems use a IPMI SEL Event message to notify the
diff --git a/hw/ppc/pnv_bmc.c b/hw/ppc/pnv_bmc.c
index 8863354..4e018b8 100644
--- a/hw/ppc/pnv_bmc.c
+++ b/hw/ppc/pnv_bmc.c
@@ -213,6 +213,18 @@
     .cmd_handlers = hiomap_cmds
 };
 
+
+void pnv_bmc_set_pnor(IPMIBmc *bmc, PnvPnor *pnor)
+{
+    object_ref(OBJECT(pnor));
+    object_property_add_const_link(OBJECT(bmc), "pnor", OBJECT(pnor),
+                                   &error_abort);
+
+    /* Install the HIOMAP protocol handlers to access the PNOR */
+    ipmi_sim_register_netfn(IPMI_BMC_SIMULATOR(bmc), IPMI_NETFN_OEM,
+                            &hiomap_netfn);
+}
+
 /*
  * Instantiate the machine BMC. PowerNV uses the QEMU internal
  * simulator but it could also be external.
@@ -232,3 +244,36 @@
 
     return IPMI_BMC(obj);
 }
+
+typedef struct ForeachArgs {
+    const char *name;
+    Object *obj;
+} ForeachArgs;
+
+static int bmc_find(Object *child, void *opaque)
+{
+    ForeachArgs *args = opaque;
+
+    if (object_dynamic_cast(child, args->name)) {
+        if (args->obj) {
+            return 1;
+        }
+        args->obj = child;
+    }
+    return 0;
+}
+
+IPMIBmc *pnv_bmc_find(Error **errp)
+{
+    ForeachArgs args = { TYPE_IPMI_BMC_SIMULATOR, NULL };
+    int ret;
+
+    ret = object_child_foreach_recursive(object_get_root(), bmc_find, &args);
+    if (ret) {
+        error_setg(errp, "machine should have only one BMC device. "
+                   "Use '-nodefaults'");
+        return NULL;
+    }
+
+    return args.obj ? IPMI_BMC(args.obj) : NULL;
+}
diff --git a/hw/ppc/ppc440_uc.c b/hw/ppc/ppc440_uc.c
index d5ea962..b30e093 100644
--- a/hw/ppc/ppc440_uc.c
+++ b/hw/ppc/ppc440_uc.c
@@ -13,7 +13,6 @@
 #include "qemu/error-report.h"
 #include "qapi/error.h"
 #include "qemu/log.h"
-#include "qemu/main-loop.h"
 #include "qemu/module.h"
 #include "cpu.h"
 #include "hw/irq.h"
@@ -1183,9 +1182,7 @@
     case PEGPL_CFGMSK:
         s->cfg_mask = val;
         size = ~(val & 0xfffffffe) + 1;
-        qemu_mutex_lock_iothread();
         pcie_host_mmcfg_update(PCIE_HOST_BRIDGE(s), val & 1, s->cfg_base, size);
-        qemu_mutex_unlock_iothread();
         break;
     case PEGPL_MSGBAH:
         s->msg_base = ((uint64_t)val << 32) | (s->msg_base & 0xffffffff);
diff --git a/hw/ppc/spapr_caps.c b/hw/ppc/spapr_caps.c
index 679ae79..eb54f94 100644
--- a/hw/ppc/spapr_caps.c
+++ b/hw/ppc/spapr_caps.c
@@ -517,9 +517,10 @@
     }
 
     if (kvm_enabled()) {
-        if (kvmppc_set_fwnmi() < 0) {
-            error_setg(errp, "Firmware Assisted Non-Maskable Interrupts(FWNMI) "
-                             "not supported by KVM");
+        if (!kvmppc_get_fwnmi()) {
+            error_setg(errp,
+"Firmware Assisted Non-Maskable Interrupts(FWNMI) not supported by KVM.");
+            error_append_hint(errp, "Try appending -machine cap-fwnmi=off\n");
         }
     }
 }
diff --git a/hw/ppc/spapr_events.c b/hw/ppc/spapr_events.c
index a4a540f..1069d01 100644
--- a/hw/ppc/spapr_events.c
+++ b/hw/ppc/spapr_events.c
@@ -833,11 +833,28 @@
     /* get rtas addr from fdt */
     rtas_addr = spapr_get_rtas_addr();
     if (!rtas_addr) {
-        qemu_system_guest_panicked(NULL);
+        if (!recovered) {
+            error_report(
+"FWNMI: Unable to deliver machine check to guest: rtas_addr not found.");
+            qemu_system_guest_panicked(NULL);
+        } else {
+            warn_report(
+"FWNMI: Unable to deliver machine check to guest: rtas_addr not found. "
+"Machine check recovered.");
+        }
         g_free(ext_elog);
         return;
     }
 
+    /*
+     * By taking the interlock, we assume that the MCE will be
+     * delivered to the guest. CAUTION: don't add anything that could
+     * prevent the MCE to be delivered after this line, otherwise the
+     * guest won't be able to release the interlock and ultimately
+     * hang/crash?
+     */
+    spapr->fwnmi_machine_check_interlock = cpu->vcpu_id;
+
     stq_be_phys(&address_space_memory, rtas_addr + RTAS_ERROR_LOG_OFFSET,
                 env->gpr[3]);
     cpu_physical_memory_write(rtas_addr + RTAS_ERROR_LOG_OFFSET +
@@ -860,17 +877,13 @@
     Error *local_err = NULL;
 
     if (spapr->fwnmi_machine_check_addr == -1) {
-        /*
-         * This implies that we have hit a machine check either when the
-         * guest has not registered FWNMI (i.e., "ibm,nmi-register" not
-         * called) or between system reset and "ibm,nmi-register".
-         * Fall back to the old machine check behavior in such cases.
-         */
+        /* Non-FWNMI case, deliver it like an architected CPU interrupt. */
         cs->exception_index = POWERPC_EXCP_MCHECK;
         ppc_cpu_do_interrupt(cs);
         return;
     }
 
+    /* Wait for FWNMI interlock. */
     while (spapr->fwnmi_machine_check_interlock != -1) {
         /*
          * Check whether the same CPU got machine check error
@@ -878,12 +891,25 @@
          * that CPU called "ibm,nmi-interlock")
          */
         if (spapr->fwnmi_machine_check_interlock == cpu->vcpu_id) {
-            qemu_system_guest_panicked(NULL);
+            if (!recovered) {
+                error_report(
+"FWNMI: Unable to deliver machine check to guest: nested machine check.");
+                qemu_system_guest_panicked(NULL);
+            } else {
+                warn_report(
+"FWNMI: Unable to deliver machine check to guest: nested machine check. "
+"Machine check recovered.");
+            }
             return;
         }
         qemu_cond_wait_iothread(&spapr->fwnmi_machine_check_interlock_cond);
-        /* Meanwhile if the system is reset, then just return */
         if (spapr->fwnmi_machine_check_addr == -1) {
+            /*
+             * If the machine was reset while waiting for the interlock,
+             * abort the delivery. The machine check applies to a context
+             * that no longer exists, so it wouldn't make sense to deliver
+             * it now.
+             */
             return;
         }
     }
@@ -894,12 +920,13 @@
          * We don't want to abort so we let the migration to continue.
          * In a rare case, the machine check handler will run on the target.
          * Though this is not preferable, it is better than aborting
-         * the migration or killing the VM.
+         * the migration or killing the VM. It is okay to call
+         * migrate_del_blocker on a blocker that was not added (which the
+         * nmi-interlock handler would do when it's called after this).
          */
         warn_report("Received a fwnmi while migration was in progress");
     }
 
-    spapr->fwnmi_machine_check_interlock = cpu->vcpu_id;
     spapr_mce_dispatch_elog(cpu, recovered);
 }
 
diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
index 709a527..55ca9de 100644
--- a/hw/ppc/spapr_pci.c
+++ b/hw/ppc/spapr_pci.c
@@ -1663,6 +1663,7 @@
 
         if (pc->is_bridge) {
             error_setg(errp, "PCI: Hot unplug of PCI bridges not supported");
+            return;
         }
 
         /* ensure any other present functions are pending unplug */
diff --git a/hw/ppc/spapr_rtas.c b/hw/ppc/spapr_rtas.c
index 9fb8c86..bcac0d0 100644
--- a/hw/ppc/spapr_rtas.c
+++ b/hw/ppc/spapr_rtas.c
@@ -437,6 +437,13 @@
         return;
     }
 
+    if (kvm_enabled()) {
+        if (kvmppc_set_fwnmi() < 0) {
+            rtas_st(rets, 0, RTAS_OUT_NOT_SUPPORTED);
+            return;
+        }
+    }
+
     spapr->fwnmi_system_reset_addr = sreset_addr;
     spapr->fwnmi_machine_check_addr = mce_addr;
 
@@ -455,6 +462,9 @@
     }
 
     if (spapr->fwnmi_machine_check_addr == -1) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+"FWNMI: ibm,nmi-interlock RTAS called with FWNMI not registered.\n");
+
         /* NMI register not called */
         rtas_st(rets, 0, RTAS_OUT_PARAM_ERROR);
         return;
diff --git a/hw/vfio/spapr.c b/hw/vfio/spapr.c
index 33692fc..2900bd1 100644
--- a/hw/vfio/spapr.c
+++ b/hw/vfio/spapr.c
@@ -147,7 +147,7 @@
 {
     int ret = 0;
     IOMMUMemoryRegion *iommu_mr = IOMMU_MEMORY_REGION(section->mr);
-    uint64_t pagesize = memory_region_iommu_get_min_page_size(iommu_mr);
+    uint64_t pagesize = memory_region_iommu_get_min_page_size(iommu_mr), pgmask;
     unsigned entries, bits_total, bits_per_level, max_levels;
     struct vfio_iommu_spapr_tce_create create = { .argsz = sizeof(create) };
     long rampagesize = qemu_minrampagesize();
@@ -159,8 +159,8 @@
     if (pagesize > rampagesize) {
         pagesize = rampagesize;
     }
-    pagesize = 1ULL << (63 - clz64(container->pgsizes &
-                                   (pagesize | (pagesize - 1))));
+    pgmask = container->pgsizes & (pagesize | (pagesize - 1));
+    pagesize = pgmask ? (1ULL << (63 - clz64(pgmask))) : 0;
     if (!pagesize) {
         error_report("Host doesn't support page size 0x%"PRIx64
                      ", the supported mask is 0x%lx",
diff --git a/include/hw/ppc/pnv.h b/include/hw/ppc/pnv.h
index fb4d0c0..d4b0b0e 100644
--- a/include/hw/ppc/pnv.h
+++ b/include/hw/ppc/pnv.h
@@ -241,6 +241,8 @@
 void pnv_dt_bmc_sensors(IPMIBmc *bmc, void *fdt);
 void pnv_bmc_powerdown(IPMIBmc *bmc);
 IPMIBmc *pnv_bmc_create(PnvPnor *pnor);
+IPMIBmc *pnv_bmc_find(Error **errp);
+void pnv_bmc_set_pnor(IPMIBmc *bmc, PnvPnor *pnor);
 
 /*
  * POWER8 MMIO base addresses
diff --git a/pc-bios/README b/pc-bios/README
index f54c274..a5a770f 100644
--- a/pc-bios/README
+++ b/pc-bios/README
@@ -14,7 +14,7 @@
 - SLOF (Slimline Open Firmware) is a free IEEE 1275 Open Firmware
   implementation for certain IBM POWER hardware.  The sources are at
   https://github.com/aik/SLOF, and the image currently in qemu is
-  built from git tag qemu-slof-20200317.
+  built from git tag qemu-slof-20200327.
 
 - sgabios (the Serial Graphics Adapter option ROM) provides a means for
   legacy x86 software to communicate with an attached serial console as
diff --git a/pc-bios/slof.bin b/pc-bios/slof.bin
index 40499a1..80bbf91 100644
--- a/pc-bios/slof.bin
+++ b/pc-bios/slof.bin
Binary files differ
diff --git a/roms/SLOF b/roms/SLOF
index ab6984f..8e012d6 160000
--- a/roms/SLOF
+++ b/roms/SLOF
@@ -1 +1 @@
-Subproject commit ab6984f5a6d054e1f634dda855b32e5357111974
+Subproject commit 8e012d6fddb62be833d746cef3f03e6c8beecde0
diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c
index 597f72b..03d0667 100644
--- a/target/ppc/kvm.c
+++ b/target/ppc/kvm.c
@@ -88,6 +88,7 @@
 static int cap_ppc_count_cache_flush_assist;
 static int cap_ppc_nested_kvm_hv;
 static int cap_large_decr;
+static int cap_fwnmi;
 
 static uint32_t debug_inst_opcode;
 
@@ -136,6 +137,7 @@
     kvmppc_get_cpu_characteristics(s);
     cap_ppc_nested_kvm_hv = kvm_vm_check_extension(s, KVM_CAP_PPC_NESTED_HV);
     cap_large_decr = kvmppc_get_dec_bits();
+    cap_fwnmi = kvm_vm_check_extension(s, KVM_CAP_PPC_FWNMI);
     /*
      * Note: setting it to false because there is not such capability
      * in KVM at this moment.
@@ -2064,6 +2066,11 @@
     }
 }
 
+bool kvmppc_get_fwnmi(void)
+{
+    return cap_fwnmi;
+}
+
 int kvmppc_set_fwnmi(void)
 {
     PowerPCCPU *cpu = POWERPC_CPU(first_cpu);
diff --git a/target/ppc/kvm_ppc.h b/target/ppc/kvm_ppc.h
index 332fa0a..fcaf745 100644
--- a/target/ppc/kvm_ppc.h
+++ b/target/ppc/kvm_ppc.h
@@ -27,6 +27,7 @@
 void kvmppc_set_papr(PowerPCCPU *cpu);
 int kvmppc_set_compat(PowerPCCPU *cpu, uint32_t compat_pvr);
 void kvmppc_set_mpic_proxy(PowerPCCPU *cpu, int mpic_proxy);
+bool kvmppc_get_fwnmi(void);
 int kvmppc_set_fwnmi(void);
 int kvmppc_smt_threads(void);
 void kvmppc_error_append_smt_possible_hint(Error *const *errp);
@@ -163,6 +164,11 @@
 {
 }
 
+static inline bool kvmppc_get_fwnmi(void)
+{
+    return false;
+}
+
 static inline int kvmppc_set_fwnmi(void)
 {
     return -1;