[PULL 00/20] ppc-for-5.2 queue 20201009

[PULL 00/20] ppc-for-5.2 queue 20201009

[David Gibson]

The following changes since commit 497d415d76b9f59fcae27f22df1ca2c3fa4df64e:

  Merge remote-tracking branch 'remotes/pmaydell/tags/pull-target-arm-20201008-1' into staging (2020-10-08 21:41:20 +0100)

are available in the Git repository at:

  git://github.com/dgibson/qemu.git tags/ppc-for-5.2-20201009

for you to fetch changes up to 307e7a34dc474c050f345eeb519d957a42f10c77:

  specs/ppc-spapr-numa: update with new NUMA support (2020-10-09 15:06:14 +1100)

----------------------------------------------------------------
ppc patch queue 2020-10-09

Here's the next set of ppc related patches for qemu-5.2.  There are
two main things here:

* Cleanups to error handling in spapr from Greg Kurz
* Improvements to NUMA handling for spapr from Daniel Barboza

There are also a handful of other bugfixes.

----------------------------------------------------------------
Cédric Le Goater (1):
      ppc/pnv: Increase max firmware size

Daniel Henrique Barboza (5):
      spapr: add spapr_machine_using_legacy_numa() helper
      spapr_numa: forbid asymmetrical NUMA setups
      spapr_numa: change reference-points and maxdomain settings
      spapr_numa: consider user input when defining associativity
      specs/ppc-spapr-numa: update with new NUMA support

Fabiano Rosas (1):
      spapr: Handle HPT allocation failure in nested guest

Greg Kurz (13):
      spapr: Fix error leak in spapr_realize_vcpu()
      ppc: Add a return value to ppc_set_compat() and ppc_set_compat_all()
      ppc: Fix return value in cpu_post_load() error path
      spapr: Simplify error handling in callers of ppc_set_compat()
      spapr: Get rid of cas_check_pvr() error reporting
      spapr: Simplify error handling in do_client_architecture_support()
      spapr: Simplify error handling in spapr_vio_busdev_realize()
      spapr: Add a return value to spapr_drc_attach()
      spapr: Simplify error handling in prop_get_fdt()
      spapr: Add a return value to spapr_set_vcpu_id()
      spapr: Simplify error handling in spapr_cpu_core_realize()
      spapr: Add a return value to spapr_nvdimm_validate()
      spapr: Add a return value to spapr_check_pagesize()

 docs/specs/ppc-spapr-numa.rst | 235 ++++++++++++++++++++++++++++++++++++++++--
 hw/ppc/pnv.c                  |   2 +-
 hw/ppc/spapr.c                |  53 +++++-----
 hw/ppc/spapr_caps.c           |   7 +-
 hw/ppc/spapr_cpu_core.c       |  24 ++---
 hw/ppc/spapr_drc.c            |  17 ++-
 hw/ppc/spapr_hcall.c          |  34 +++---
 hw/ppc/spapr_numa.c           | 185 +++++++++++++++++++++++++++++++--
 hw/ppc/spapr_nvdimm.c         |  19 ++--
 hw/ppc/spapr_pci.c            |   5 +-
 hw/ppc/spapr_vio.c            |  12 +--
 include/hw/ppc/spapr.h        |   6 +-
 include/hw/ppc/spapr_drc.h    |   2 +-
 include/hw/ppc/spapr_nvdimm.h |   2 +-
 target/ppc/compat.c           |  26 +++--
 target/ppc/cpu.h              |   4 +-
 target/ppc/machine.c          |   9 +-
 17 files changed, 514 insertions(+), 128 deletions(-)

[PULL 01/20] spapr: Handle HPT allocation failure in nested guest

[David Gibson]

From: Fabiano Rosas <farosas@linux.ibm.com>

The nested KVM code does not yet support HPT guests. Calling the
KVM_CAP_PPC_ALLOC_HTAB ioctl currently leads to KVM setting the guest
as HPT and erroneously executing code in L1 that should only run in
hypervisor mode, leading to an exception in the L1 vcpu thread when it
enters the nested guest.

This can be reproduced with -machine max-cpu-compat=power8 in the L2
guest command line.

The KVM code has since been modified to fail the ioctl when running in
a nested environment so QEMU needs to be able to handle that. This
patch provides an error message informing the user about the lack of
support for HPT in nested guests.

Reported-by: Satheesh Rajendran <sathnaga@linux.vnet.ibm.com>
Signed-off-by: Fabiano Rosas <farosas@linux.ibm.com>
Message-Id: <20200911043123.204162-1-farosas@linux.ibm.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 hw/ppc/spapr.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 2db810f73a..544a1947d9 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -1483,6 +1483,12 @@ void spapr_reallocate_hpt(SpaprMachineState *spapr, int shift,
     spapr_free_hpt(spapr);
 
     rc = kvmppc_reset_htab(shift);
+
+    if (rc == -EOPNOTSUPP) {
+        error_setg(errp, "HPT not supported in nested guests");
+        return;
+    }
+
     if (rc < 0) {
         /* kernel-side HPT needed, but couldn't allocate one */
         error_setg_errno(errp, errno,
-- 
2.26.2

[PULL 02/20] spapr: Fix error leak in spapr_realize_vcpu()

[David Gibson]

From: Greg Kurz <groug@kaod.org>

If spapr_irq_cpu_intc_create() fails, local_err isn't propagated and
thus leaked.

Fixes: 992861fb1e4c ("error: Eliminate error_propagate() manually")
Cc: armbru@redhat.com
Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <20200914123505.612812-2-groug@kaod.org>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 hw/ppc/spapr_cpu_core.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/hw/ppc/spapr_cpu_core.c b/hw/ppc/spapr_cpu_core.c
index 2125fdac34..3e4f402b2e 100644
--- a/hw/ppc/spapr_cpu_core.c
+++ b/hw/ppc/spapr_cpu_core.c
@@ -232,7 +232,6 @@ static void spapr_realize_vcpu(PowerPCCPU *cpu, SpaprMachineState *spapr,
 {
     CPUPPCState *env = &cpu->env;
     CPUState *cs = CPU(cpu);
-    Error *local_err = NULL;
 
     if (!qdev_realize(DEVICE(cpu), NULL, errp)) {
         return;
@@ -244,7 +243,7 @@ static void spapr_realize_vcpu(PowerPCCPU *cpu, SpaprMachineState *spapr,
     cpu_ppc_set_vhyp(cpu, PPC_VIRTUAL_HYPERVISOR(spapr));
     kvmppc_set_papr(cpu);
 
-    if (spapr_irq_cpu_intc_create(spapr, cpu, &local_err) < 0) {
+    if (spapr_irq_cpu_intc_create(spapr, cpu, errp) < 0) {
         cpu_remove_sync(CPU(cpu));
         return;
     }
-- 
2.26.2

[PULL 03/20] ppc: Add a return value to ppc_set_compat() and ppc_set_compat_all()

[David Gibson]

From: Greg Kurz <groug@kaod.org>

As recommended in "qapi/error.h", indicate success / failure with a
return value. Since ppc_set_compat() is called from a VMState handler,
let's make it an int so that it propagates any negative errno returned
by kvmppc_set_compat(). Do the same for ppc_set_compat_all() for
consistency, even if it isn't called in a context where a negative errno
is required on failure.

This will allow to simplify error handling in the callers.

Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <20200914123505.612812-3-groug@kaod.org>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 target/ppc/compat.c | 26 +++++++++++++++-----------
 target/ppc/cpu.h    |  4 ++--
 2 files changed, 17 insertions(+), 13 deletions(-)

diff --git a/target/ppc/compat.c b/target/ppc/compat.c
index 08aede88dc..e9bec5ffed 100644
--- a/target/ppc/compat.c
+++ b/target/ppc/compat.c
@@ -158,7 +158,7 @@ bool ppc_type_check_compat(const char *cputype, uint32_t compat_pvr,
     return pcc_compat(pcc, compat_pvr, min_compat_pvr, max_compat_pvr);
 }
 
-void ppc_set_compat(PowerPCCPU *cpu, uint32_t compat_pvr, Error **errp)
+int ppc_set_compat(PowerPCCPU *cpu, uint32_t compat_pvr, Error **errp)
 {
     const CompatInfo *compat = compat_by_pvr(compat_pvr);
     CPUPPCState *env = &cpu->env;
@@ -169,11 +169,11 @@ void ppc_set_compat(PowerPCCPU *cpu, uint32_t compat_pvr, Error **errp)
         pcr = 0;
     } else if (!compat) {
         error_setg(errp, "Unknown compatibility PVR 0x%08"PRIx32, compat_pvr);
-        return;
+        return -EINVAL;
     } else if (!ppc_check_compat(cpu, compat_pvr, 0, 0)) {
         error_setg(errp, "Compatibility PVR 0x%08"PRIx32" not valid for CPU",
                    compat_pvr);
-        return;
+        return -EINVAL;
     } else {
         pcr = compat->pcr;
     }
@@ -185,17 +185,19 @@ void ppc_set_compat(PowerPCCPU *cpu, uint32_t compat_pvr, Error **errp)
         if (ret < 0) {
             error_setg_errno(errp, -ret,
                              "Unable to set CPU compatibility mode in KVM");
-            return;
+            return ret;
         }
     }
 
     cpu->compat_pvr = compat_pvr;
     env->spr[SPR_PCR] = pcr & pcc->pcr_mask;
+    return 0;
 }
 
 typedef struct {
     uint32_t compat_pvr;
-    Error *err;
+    Error **errp;
+    int ret;
 } SetCompatState;
 
 static void do_set_compat(CPUState *cs, run_on_cpu_data arg)
@@ -203,26 +205,28 @@ static void do_set_compat(CPUState *cs, run_on_cpu_data arg)
     PowerPCCPU *cpu = POWERPC_CPU(cs);
     SetCompatState *s = arg.host_ptr;
 
-    ppc_set_compat(cpu, s->compat_pvr, &s->err);
+    s->ret = ppc_set_compat(cpu, s->compat_pvr, s->errp);
 }
 
-void ppc_set_compat_all(uint32_t compat_pvr, Error **errp)
+int ppc_set_compat_all(uint32_t compat_pvr, Error **errp)
 {
     CPUState *cs;
 
     CPU_FOREACH(cs) {
         SetCompatState s = {
             .compat_pvr = compat_pvr,
-            .err = NULL,
+            .errp = errp,
+            .ret = 0,
         };
 
         run_on_cpu(cs, do_set_compat, RUN_ON_CPU_HOST_PTR(&s));
 
-        if (s.err) {
-            error_propagate(errp, s.err);
-            return;
+        if (s.ret < 0) {
+            return s.ret;
         }
     }
+
+    return 0;
 }
 
 int ppc_compat_max_vthreads(PowerPCCPU *cpu)
diff --git a/target/ppc/cpu.h b/target/ppc/cpu.h
index 766e9c5c26..e8aa185d4f 100644
--- a/target/ppc/cpu.h
+++ b/target/ppc/cpu.h
@@ -1352,10 +1352,10 @@ bool ppc_check_compat(PowerPCCPU *cpu, uint32_t compat_pvr,
 bool ppc_type_check_compat(const char *cputype, uint32_t compat_pvr,
                            uint32_t min_compat_pvr, uint32_t max_compat_pvr);
 
-void ppc_set_compat(PowerPCCPU *cpu, uint32_t compat_pvr, Error **errp);
+int ppc_set_compat(PowerPCCPU *cpu, uint32_t compat_pvr, Error **errp);
 
 #if !defined(CONFIG_USER_ONLY)
-void ppc_set_compat_all(uint32_t compat_pvr, Error **errp);
+int ppc_set_compat_all(uint32_t compat_pvr, Error **errp);
 #endif
 int ppc_compat_max_vthreads(PowerPCCPU *cpu);
 void ppc_compat_add_property(Object *obj, const char *name,
-- 
2.26.2

[PULL 04/20] ppc: Fix return value in cpu_post_load() error path

[David Gibson]

From: Greg Kurz <groug@kaod.org>

VMState handlers are supposed to return negative errno values on failure.

Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <20200914123505.612812-4-groug@kaod.org>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 target/ppc/machine.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/target/ppc/machine.c b/target/ppc/machine.c
index 109d071162..5e58377376 100644
--- a/target/ppc/machine.c
+++ b/target/ppc/machine.c
@@ -347,18 +347,19 @@ static int cpu_post_load(void *opaque, int version_id)
     if (cpu->compat_pvr) {
         uint32_t compat_pvr = cpu->compat_pvr;
         Error *local_err = NULL;
+        int ret;
 
         cpu->compat_pvr = 0;
-        ppc_set_compat(cpu, compat_pvr, &local_err);
-        if (local_err) {
+        ret = ppc_set_compat(cpu, compat_pvr, &local_err);
+        if (ret < 0) {
             error_report_err(local_err);
-            return -1;
+            return ret;
         }
     } else
 #endif
     {
         if (!pvr_match(cpu, env->spr[SPR_PVR])) {
-            return -1;
+            return -EINVAL;
         }
     }
 
-- 
2.26.2

[PULL 05/20] spapr: Simplify error handling in callers of ppc_set_compat()

[David Gibson]

From: Greg Kurz <groug@kaod.org>

Now that ppc_set_compat() indicates success/failure with a return
value, use it and reduce error propagation overhead.

Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <20200914123505.612812-5-groug@kaod.org>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 hw/ppc/spapr.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 544a1947d9..0f82e657e3 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -3817,10 +3817,9 @@ static void spapr_core_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
      */
     if (hotplugged) {
         for (i = 0; i < cc->nr_threads; i++) {
-            ppc_set_compat(core->threads[i], POWERPC_CPU(first_cpu)->compat_pvr,
-                           &local_err);
-            if (local_err) {
-                error_propagate(errp, local_err);
+            if (ppc_set_compat(core->threads[i],
+                               POWERPC_CPU(first_cpu)->compat_pvr,
+                               errp) < 0) {
                 return;
             }
         }
-- 
2.26.2

[PULL 06/20] spapr: Get rid of cas_check_pvr() error reporting

[David Gibson]

From: Greg Kurz <groug@kaod.org>

The cas_check_pvr() function has two purposes:
- finding the "best" logical PVR, ie. the most recent one supported by
  the guest for this CPU type
- checking if the guest supports the real PVR of this CPU type, which
  is just an optional extra information to workaround the lack of
  support for "compat" mode in PR KVM

This logic doesn't need error reporting, really. If we don't find a
suitable logical PVR, we return the special value 0 which is definitely
not a valid PVR. Let the caller decide on whether it should error out
or not.

This doesn't change the behavior.

Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <20200914123505.612812-6-groug@kaod.org>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 hw/ppc/spapr_hcall.c | 27 ++++++++++++---------------
 1 file changed, 12 insertions(+), 15 deletions(-)

diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c
index c2776b6a7d..885ea60778 100644
--- a/hw/ppc/spapr_hcall.c
+++ b/hw/ppc/spapr_hcall.c
@@ -1590,12 +1590,11 @@ static target_ulong h_signal_sys_reset(PowerPCCPU *cpu,
     }
 }
 
-static uint32_t cas_check_pvr(SpaprMachineState *spapr, PowerPCCPU *cpu,
-                              target_ulong *addr, bool *raw_mode_supported,
-                              Error **errp)
+/* Returns either a logical PVR or zero if none was found */
+static uint32_t cas_check_pvr(PowerPCCPU *cpu, uint32_t max_compat,
+                              target_ulong *addr, bool *raw_mode_supported)
 {
     bool explicit_match = false; /* Matched the CPU's real PVR */
-    uint32_t max_compat = spapr->max_compat_pvr;
     uint32_t best_compat = 0;
     int i;
 
@@ -1624,14 +1623,6 @@ static uint32_t cas_check_pvr(SpaprMachineState *spapr, PowerPCCPU *cpu,
         }
     }
 
-    if ((best_compat == 0) && (!explicit_match || max_compat)) {
-        /* We couldn't find a suitable compatibility mode, and either
-         * the guest doesn't support "raw" mode for this CPU, or raw
-         * mode is disabled because a maximum compat mode is set */
-        error_setg(errp, "Couldn't negotiate a suitable PVR during CAS");
-        return 0;
-    }
-
     *raw_mode_supported = explicit_match;
 
     /* Parsing finished */
@@ -1680,6 +1671,7 @@ target_ulong do_client_architecture_support(PowerPCCPU *cpu,
     bool guest_xive;
     CPUState *cs;
     void *fdt;
+    uint32_t max_compat = spapr->max_compat_pvr;
 
     /* CAS is supposed to be called early when only the boot vCPU is active. */
     CPU_FOREACH(cs) {
@@ -1692,9 +1684,14 @@ target_ulong do_client_architecture_support(PowerPCCPU *cpu,
         }
     }
 
-    cas_pvr = cas_check_pvr(spapr, cpu, &vec, &raw_mode_supported, &local_err);
-    if (local_err) {
-        error_report_err(local_err);
+    cas_pvr = cas_check_pvr(cpu, max_compat, &vec, &raw_mode_supported);
+    if (!cas_pvr && (!raw_mode_supported || max_compat)) {
+        /*
+         * We couldn't find a suitable compatibility mode, and either
+         * the guest doesn't support "raw" mode for this CPU, or "raw"
+         * mode is disabled because a maximum compat mode is set.
+         */
+        error_report("Couldn't negotiate a suitable PVR during CAS");
         return H_HARDWARE;
     }
 
-- 
2.26.2

[PULL 07/20] spapr: Simplify error handling in do_client_architecture_support()

[David Gibson]

From: Greg Kurz <groug@kaod.org>

Use the return value of ppc_set_compat_all() to check failures,
which is preferred over hijacking local_err.

Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <20200914123505.612812-7-groug@kaod.org>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 hw/ppc/spapr_hcall.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c
index 885ea60778..607740150f 100644
--- a/hw/ppc/spapr_hcall.c
+++ b/hw/ppc/spapr_hcall.c
@@ -1666,7 +1666,6 @@ target_ulong do_client_architecture_support(PowerPCCPU *cpu,
     uint32_t cas_pvr;
     SpaprOptionVector *ov1_guest, *ov5_guest;
     bool guest_radix;
-    Error *local_err = NULL;
     bool raw_mode_supported = false;
     bool guest_xive;
     CPUState *cs;
@@ -1697,8 +1696,9 @@ target_ulong do_client_architecture_support(PowerPCCPU *cpu,
 
     /* Update CPUs */
     if (cpu->compat_pvr != cas_pvr) {
-        ppc_set_compat_all(cas_pvr, &local_err);
-        if (local_err) {
+        Error *local_err = NULL;
+
+        if (ppc_set_compat_all(cas_pvr, &local_err) < 0) {
             /* We fail to set compat mode (likely because running with KVM PR),
              * but maybe we can fallback to raw mode if the guest supports it.
              */
@@ -1707,7 +1707,6 @@ target_ulong do_client_architecture_support(PowerPCCPU *cpu,
                 return H_HARDWARE;
             }
             error_free(local_err);
-            local_err = NULL;
         }
     }
 
-- 
2.26.2

[PULL 08/20] spapr: Simplify error handling in spapr_vio_busdev_realize()

[David Gibson]

From: Greg Kurz <groug@kaod.org>

Use the return value of spapr_irq_findone() and spapr_irq_claim()
to detect failures. This allows to reduce the error propagation
overhead.

Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <20200914123505.612812-8-groug@kaod.org>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 hw/ppc/spapr_vio.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/hw/ppc/spapr_vio.c b/hw/ppc/spapr_vio.c
index 731080d989..44fdd64b88 100644
--- a/hw/ppc/spapr_vio.c
+++ b/hw/ppc/spapr_vio.c
@@ -474,7 +474,6 @@ static void spapr_vio_busdev_realize(DeviceState *qdev, Error **errp)
     SpaprVioDevice *dev = (SpaprVioDevice *)qdev;
     SpaprVioDeviceClass *pc = VIO_SPAPR_DEVICE_GET_CLASS(dev);
     char *id;
-    Error *local_err = NULL;
 
     if (dev->reg != -1) {
         /*
@@ -510,16 +509,15 @@ static void spapr_vio_busdev_realize(DeviceState *qdev, Error **errp)
     dev->irq = spapr_vio_reg_to_irq(dev->reg);
 
     if (SPAPR_MACHINE_GET_CLASS(spapr)->legacy_irq_allocation) {
-        dev->irq = spapr_irq_findone(spapr, &local_err);
-        if (local_err) {
-            error_propagate(errp, local_err);
+        int irq = spapr_irq_findone(spapr, errp);
+
+        if (irq < 0) {
             return;
         }
+        dev->irq = irq;
     }
 
-    spapr_irq_claim(spapr, dev->irq, false, &local_err);
-    if (local_err) {
-        error_propagate(errp, local_err);
+    if (spapr_irq_claim(spapr, dev->irq, false, errp) < 0) {
         return;
     }
 
-- 
2.26.2

[PULL 09/20] spapr: Add a return value to spapr_drc_attach()

[David Gibson]

From: Greg Kurz <groug@kaod.org>

As recommended in "qapi/error.h", return true on success and false on
failure. This allows to reduce error propagation overhead in the callers.

Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <20200914123505.612812-9-groug@kaod.org>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 hw/ppc/spapr.c             | 15 +++------------
 hw/ppc/spapr_drc.c         |  5 +++--
 hw/ppc/spapr_nvdimm.c      |  5 +----
 hw/ppc/spapr_pci.c         |  5 +----
 include/hw/ppc/spapr_drc.h |  2 +-
 5 files changed, 9 insertions(+), 23 deletions(-)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 0f82e657e3..26b3432fe4 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -3371,22 +3371,19 @@ static void spapr_add_lmbs(DeviceState *dev, uint64_t addr_start, uint64_t size,
     int i;
     uint64_t addr = addr_start;
     bool hotplugged = spapr_drc_hotplugged(dev);
-    Error *local_err = NULL;
 
     for (i = 0; i < nr_lmbs; i++) {
         drc = spapr_drc_by_id(TYPE_SPAPR_DRC_LMB,
                               addr / SPAPR_MEMORY_BLOCK_SIZE);
         g_assert(drc);
 
-        spapr_drc_attach(drc, dev, &local_err);
-        if (local_err) {
+        if (!spapr_drc_attach(drc, dev, errp)) {
             while (addr > addr_start) {
                 addr -= SPAPR_MEMORY_BLOCK_SIZE;
                 drc = spapr_drc_by_id(TYPE_SPAPR_DRC_LMB,
                                       addr / SPAPR_MEMORY_BLOCK_SIZE);
                 spapr_drc_detach(drc);
             }
-            error_propagate(errp, local_err);
             return;
         }
         if (!hotplugged) {
@@ -3767,7 +3764,6 @@ static void spapr_core_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
     CPUCore *cc = CPU_CORE(dev);
     CPUState *cs;
     SpaprDrc *drc;
-    Error *local_err = NULL;
     CPUArchId *core_slot;
     int index;
     bool hotplugged = spapr_drc_hotplugged(dev);
@@ -3785,9 +3781,7 @@ static void spapr_core_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
     g_assert(drc || !mc->has_hotpluggable_cpus);
 
     if (drc) {
-        spapr_drc_attach(drc, dev, &local_err);
-        if (local_err) {
-            error_propagate(errp, local_err);
+        if (!spapr_drc_attach(drc, dev, errp)) {
             return;
         }
 
@@ -3939,7 +3933,6 @@ static void spapr_phb_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
     SpaprPhbState *sphb = SPAPR_PCI_HOST_BRIDGE(dev);
     SpaprDrc *drc;
     bool hotplugged = spapr_drc_hotplugged(dev);
-    Error *local_err = NULL;
 
     if (!smc->dr_phb_enabled) {
         return;
@@ -3949,9 +3942,7 @@ static void spapr_phb_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
     /* hotplug hooks should check it's enabled before getting this far */
     assert(drc);
 
-    spapr_drc_attach(drc, dev, &local_err);
-    if (local_err) {
-        error_propagate(errp, local_err);
+    if (!spapr_drc_attach(drc, dev, errp)) {
         return;
     }
 
diff --git a/hw/ppc/spapr_drc.c b/hw/ppc/spapr_drc.c
index fe998d8108..04a6bf134e 100644
--- a/hw/ppc/spapr_drc.c
+++ b/hw/ppc/spapr_drc.c
@@ -371,13 +371,13 @@ static void prop_get_fdt(Object *obj, Visitor *v, const char *name,
     } while (fdt_depth != 0);
 }
 
-void spapr_drc_attach(SpaprDrc *drc, DeviceState *d, Error **errp)
+bool spapr_drc_attach(SpaprDrc *drc, DeviceState *d, Error **errp)
 {
     trace_spapr_drc_attach(spapr_drc_index(drc));
 
     if (drc->dev) {
         error_setg(errp, "an attached device is still awaiting release");
-        return;
+        return false;
     }
     g_assert((drc->state == SPAPR_DRC_STATE_LOGICAL_UNUSABLE)
              || (drc->state == SPAPR_DRC_STATE_PHYSICAL_POWERON));
@@ -388,6 +388,7 @@ void spapr_drc_attach(SpaprDrc *drc, DeviceState *d, Error **errp)
                              object_get_typename(OBJECT(drc->dev)),
                              (Object **)(&drc->dev),
                              NULL, 0);
+    return true;
 }
 
 static void spapr_drc_release(SpaprDrc *drc)
diff --git a/hw/ppc/spapr_nvdimm.c b/hw/ppc/spapr_nvdimm.c
index 63872054f3..c06f903e5b 100644
--- a/hw/ppc/spapr_nvdimm.c
+++ b/hw/ppc/spapr_nvdimm.c
@@ -91,14 +91,11 @@ void spapr_add_nvdimm(DeviceState *dev, uint64_t slot, Error **errp)
 {
     SpaprDrc *drc;
     bool hotplugged = spapr_drc_hotplugged(dev);
-    Error *local_err = NULL;
 
     drc = spapr_drc_by_id(TYPE_SPAPR_DRC_PMEM, slot);
     g_assert(drc);
 
-    spapr_drc_attach(drc, dev, &local_err);
-    if (local_err) {
-        error_propagate(errp, local_err);
+    if (!spapr_drc_attach(drc, dev, errp)) {
         return;
     }
 
diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
index 5db912b48c..3999392b32 100644
--- a/hw/ppc/spapr_pci.c
+++ b/hw/ppc/spapr_pci.c
@@ -1539,7 +1539,6 @@ static void spapr_pci_plug(HotplugHandler *plug_handler,
     PCIDevice *pdev = PCI_DEVICE(plugged_dev);
     PCIDeviceClass *pc = PCI_DEVICE_GET_CLASS(plugged_dev);
     SpaprDrc *drc = drc_from_dev(phb, pdev);
-    Error *local_err = NULL;
     PCIBus *bus = PCI_BUS(qdev_get_parent_bus(DEVICE(pdev)));
     uint32_t slotnr = PCI_SLOT(pdev->devfn);
 
@@ -1578,9 +1577,7 @@ static void spapr_pci_plug(HotplugHandler *plug_handler,
         return;
     }
 
-    spapr_drc_attach(drc, DEVICE(pdev), &local_err);
-    if (local_err) {
-        error_propagate(errp, local_err);
+    if (!spapr_drc_attach(drc, DEVICE(pdev), errp)) {
         return;
     }
 
diff --git a/include/hw/ppc/spapr_drc.h b/include/hw/ppc/spapr_drc.h
index f270860769..165b281496 100644
--- a/include/hw/ppc/spapr_drc.h
+++ b/include/hw/ppc/spapr_drc.h
@@ -235,7 +235,7 @@ SpaprDrc *spapr_drc_by_index(uint32_t index);
 SpaprDrc *spapr_drc_by_id(const char *type, uint32_t id);
 int spapr_dt_drc(void *fdt, int offset, Object *owner, uint32_t drc_type_mask);
 
-void spapr_drc_attach(SpaprDrc *drc, DeviceState *d, Error **errp);
+bool spapr_drc_attach(SpaprDrc *drc, DeviceState *d, Error **errp);
 void spapr_drc_detach(SpaprDrc *drc);
 
 /* Returns true if a hot plug/unplug request is pending */
-- 
2.26.2

[PULL 10/20] spapr: Simplify error handling in prop_get_fdt()

[David Gibson]

From: Greg Kurz <groug@kaod.org>

Use the return value of visit_check_struct() and visit_check_list()
for error checking instead of local_err. This allows to get rid of
the error propagation overhead.

Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <20200914123505.612812-10-groug@kaod.org>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 hw/ppc/spapr_drc.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/hw/ppc/spapr_drc.c b/hw/ppc/spapr_drc.c
index 04a6bf134e..697b28c343 100644
--- a/hw/ppc/spapr_drc.c
+++ b/hw/ppc/spapr_drc.c
@@ -302,7 +302,6 @@ static void prop_get_fdt(Object *obj, Visitor *v, const char *name,
 {
     SpaprDrc *drc = SPAPR_DR_CONNECTOR(obj);
     QNull *null = NULL;
-    Error *err = NULL;
     int fdt_offset_next, fdt_offset, fdt_depth;
     void *fdt;
 
@@ -321,6 +320,7 @@ static void prop_get_fdt(Object *obj, Visitor *v, const char *name,
         const struct fdt_property *prop = NULL;
         int prop_len = 0, name_len = 0;
         uint32_t tag;
+        bool ok;
 
         tag = fdt_next_tag(fdt, fdt_offset, &fdt_offset_next);
         switch (tag) {
@@ -334,10 +334,9 @@ static void prop_get_fdt(Object *obj, Visitor *v, const char *name,
         case FDT_END_NODE:
             /* shouldn't ever see an FDT_END_NODE before FDT_BEGIN_NODE */
             g_assert(fdt_depth > 0);
-            visit_check_struct(v, &err);
+            ok = visit_check_struct(v, errp);
             visit_end_struct(v, NULL);
-            if (err) {
-                error_propagate(errp, err);
+            if (!ok) {
                 return;
             }
             fdt_depth--;
@@ -355,10 +354,9 @@ static void prop_get_fdt(Object *obj, Visitor *v, const char *name,
                     return;
                 }
             }
-            visit_check_list(v, &err);
+            ok = visit_check_list(v, errp);
             visit_end_list(v, NULL);
-            if (err) {
-                error_propagate(errp, err);
+            if (!ok) {
                 return;
             }
             break;
-- 
2.26.2

[PULL 11/20] spapr: Add a return value to spapr_set_vcpu_id()

[David Gibson]

From: Greg Kurz <groug@kaod.org>

As recommended in "qapi/error.h", return true on success and false on
failure. This allows to reduce error propagation overhead in the callers.

Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <20200914123505.612812-11-groug@kaod.org>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 hw/ppc/spapr.c          | 5 +++--
 hw/ppc/spapr_cpu_core.c | 5 +----
 include/hw/ppc/spapr.h  | 2 +-
 3 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 26b3432fe4..c6af456cfc 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -4286,7 +4286,7 @@ int spapr_get_vcpu_id(PowerPCCPU *cpu)
     return cpu->vcpu_id;
 }
 
-void spapr_set_vcpu_id(PowerPCCPU *cpu, int cpu_index, Error **errp)
+bool spapr_set_vcpu_id(PowerPCCPU *cpu, int cpu_index, Error **errp)
 {
     SpaprMachineState *spapr = SPAPR_MACHINE(qdev_get_machine());
     MachineState *ms = MACHINE(spapr);
@@ -4299,10 +4299,11 @@ void spapr_set_vcpu_id(PowerPCCPU *cpu, int cpu_index, Error **errp)
         error_append_hint(errp, "Adjust the number of cpus to %d "
                           "or try to raise the number of threads per core\n",
                           vcpu_id * ms->smp.threads / spapr->vsmt);
-        return;
+        return false;
     }
 
     cpu->vcpu_id = vcpu_id;
+    return true;
 }
 
 PowerPCCPU *spapr_find_cpu(int vcpu_id)
diff --git a/hw/ppc/spapr_cpu_core.c b/hw/ppc/spapr_cpu_core.c
index 3e4f402b2e..0c879d4da2 100644
--- a/hw/ppc/spapr_cpu_core.c
+++ b/hw/ppc/spapr_cpu_core.c
@@ -262,7 +262,6 @@ static PowerPCCPU *spapr_create_vcpu(SpaprCpuCore *sc, int i, Error **errp)
     char *id;
     CPUState *cs;
     PowerPCCPU *cpu;
-    Error *local_err = NULL;
 
     obj = object_new(scc->cpu_type);
 
@@ -274,8 +273,7 @@ static PowerPCCPU *spapr_create_vcpu(SpaprCpuCore *sc, int i, Error **errp)
      */
     cs->start_powered_off = true;
     cs->cpu_index = cc->core_id + i;
-    spapr_set_vcpu_id(cpu, cs->cpu_index, &local_err);
-    if (local_err) {
+    if (!spapr_set_vcpu_id(cpu, cs->cpu_index, errp)) {
         goto err;
     }
 
@@ -292,7 +290,6 @@ static PowerPCCPU *spapr_create_vcpu(SpaprCpuCore *sc, int i, Error **errp)
 
 err:
     object_unref(obj);
-    error_propagate(errp, local_err);
     return NULL;
 }
 
diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
index 194f3b9d07..02f3c29838 100644
--- a/include/hw/ppc/spapr.h
+++ b/include/hw/ppc/spapr.h
@@ -902,7 +902,7 @@ void spapr_do_system_reset_on_cpu(CPUState *cs, run_on_cpu_data arg);
 #define HTAB_SIZE(spapr)        (1ULL << ((spapr)->htab_shift))
 
 int spapr_get_vcpu_id(PowerPCCPU *cpu);
-void spapr_set_vcpu_id(PowerPCCPU *cpu, int cpu_index, Error **errp);
+bool spapr_set_vcpu_id(PowerPCCPU *cpu, int cpu_index, Error **errp);
 PowerPCCPU *spapr_find_cpu(int vcpu_id);
 
 int spapr_caps_pre_load(void *opaque);
-- 
2.26.2

[PULL 12/20] spapr: Simplify error handling in spapr_cpu_core_realize()

[David Gibson]

From: Greg Kurz <groug@kaod.org>

As recommended in "qapi/error.h", add a bool return value to
spapr_realize_vcpu() and use it in spapr_cpu_core_realize()
in order to get rid of the error propagation overhead.

Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <20200914123505.612812-12-groug@kaod.org>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 hw/ppc/spapr_cpu_core.c | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/hw/ppc/spapr_cpu_core.c b/hw/ppc/spapr_cpu_core.c
index 0c879d4da2..b03620823a 100644
--- a/hw/ppc/spapr_cpu_core.c
+++ b/hw/ppc/spapr_cpu_core.c
@@ -227,14 +227,14 @@ static void spapr_cpu_core_unrealize(DeviceState *dev)
     g_free(sc->threads);
 }
 
-static void spapr_realize_vcpu(PowerPCCPU *cpu, SpaprMachineState *spapr,
+static bool spapr_realize_vcpu(PowerPCCPU *cpu, SpaprMachineState *spapr,
                                SpaprCpuCore *sc, Error **errp)
 {
     CPUPPCState *env = &cpu->env;
     CPUState *cs = CPU(cpu);
 
     if (!qdev_realize(DEVICE(cpu), NULL, errp)) {
-        return;
+        return false;
     }
 
     /* Set time-base frequency to 512 MHz */
@@ -245,13 +245,14 @@ static void spapr_realize_vcpu(PowerPCCPU *cpu, SpaprMachineState *spapr,
 
     if (spapr_irq_cpu_intc_create(spapr, cpu, errp) < 0) {
         cpu_remove_sync(CPU(cpu));
-        return;
+        return false;
     }
 
     if (!sc->pre_3_0_migration) {
         vmstate_register(NULL, cs->cpu_index, &vmstate_spapr_cpu_state,
                          cpu->machine_data);
     }
+    return true;
 }
 
 static PowerPCCPU *spapr_create_vcpu(SpaprCpuCore *sc, int i, Error **errp)
@@ -312,7 +313,6 @@ static void spapr_cpu_core_realize(DeviceState *dev, Error **errp)
                                                   TYPE_SPAPR_MACHINE);
     SpaprCpuCore *sc = SPAPR_CPU_CORE(OBJECT(dev));
     CPUCore *cc = CPU_CORE(OBJECT(dev));
-    Error *local_err = NULL;
     int i, j;
 
     if (!spapr) {
@@ -322,15 +322,14 @@ static void spapr_cpu_core_realize(DeviceState *dev, Error **errp)
 
     sc->threads = g_new(PowerPCCPU *, cc->nr_threads);
     for (i = 0; i < cc->nr_threads; i++) {
-        sc->threads[i] = spapr_create_vcpu(sc, i, &local_err);
-        if (local_err) {
+        sc->threads[i] = spapr_create_vcpu(sc, i, errp);
+        if (!sc->threads[i]) {
             goto err;
         }
     }
 
     for (j = 0; j < cc->nr_threads; j++) {
-        spapr_realize_vcpu(sc->threads[j], spapr, sc, &local_err);
-        if (local_err) {
+        if (!spapr_realize_vcpu(sc->threads[j], spapr, sc, errp)) {
             goto err_unrealize;
         }
     }
@@ -347,7 +346,6 @@ err:
         spapr_delete_vcpu(sc->threads[i], sc);
     }
     g_free(sc->threads);
-    error_propagate(errp, local_err);
 }
 
 static Property spapr_cpu_core_properties[] = {
-- 
2.26.2

[PULL 13/20] spapr: Add a return value to spapr_nvdimm_validate()

[David Gibson]

From: Greg Kurz <groug@kaod.org>

As recommended in "qapi/error.h", return true on success and false on
failure. This allows to reduce error propagation overhead in the callers.

Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <20200914123505.612812-13-groug@kaod.org>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 hw/ppc/spapr.c                |  4 +---
 hw/ppc/spapr_nvdimm.c         | 14 ++++++++------
 include/hw/ppc/spapr_nvdimm.h |  2 +-
 3 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index c6af456cfc..7f3a620d41 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -3478,9 +3478,7 @@ static void spapr_memory_pre_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
     }
 
     if (is_nvdimm) {
-        spapr_nvdimm_validate(hotplug_dev, NVDIMM(dev), size, &local_err);
-        if (local_err) {
-            error_propagate(errp, local_err);
+        if (!spapr_nvdimm_validate(hotplug_dev, NVDIMM(dev), size, errp)) {
             return;
         }
     } else if (size % SPAPR_MEMORY_BLOCK_SIZE) {
diff --git a/hw/ppc/spapr_nvdimm.c b/hw/ppc/spapr_nvdimm.c
index c06f903e5b..b3a489e9fe 100644
--- a/hw/ppc/spapr_nvdimm.c
+++ b/hw/ppc/spapr_nvdimm.c
@@ -33,7 +33,7 @@
 #include "sysemu/sysemu.h"
 #include "hw/ppc/spapr_numa.h"
 
-void spapr_nvdimm_validate(HotplugHandler *hotplug_dev, NVDIMMDevice *nvdimm,
+bool spapr_nvdimm_validate(HotplugHandler *hotplug_dev, NVDIMMDevice *nvdimm,
                            uint64_t size, Error **errp)
 {
     const MachineClass *mc = MACHINE_GET_CLASS(hotplug_dev);
@@ -45,7 +45,7 @@ void spapr_nvdimm_validate(HotplugHandler *hotplug_dev, NVDIMMDevice *nvdimm,
 
     if (!mc->nvdimm_supported) {
         error_setg(errp, "NVDIMM hotplug not supported for this machine");
-        return;
+        return false;
     }
 
     /*
@@ -59,20 +59,20 @@ void spapr_nvdimm_validate(HotplugHandler *hotplug_dev, NVDIMMDevice *nvdimm,
      */
     if (!ms->nvdimms_state->is_enabled && nvdimm_opt) {
         error_setg(errp, "nvdimm device found but 'nvdimm=off' was set");
-        return;
+        return false;
     }
 
     if (object_property_get_int(OBJECT(nvdimm), NVDIMM_LABEL_SIZE_PROP,
                                 &error_abort) == 0) {
         error_setg(errp, "PAPR requires NVDIMM devices to have label-size set");
-        return;
+        return false;
     }
 
     if (size % SPAPR_MINIMUM_SCM_BLOCK_SIZE) {
         error_setg(errp, "PAPR requires NVDIMM memory size (excluding label)"
                    " to be a multiple of %" PRIu64 "MB",
                    SPAPR_MINIMUM_SCM_BLOCK_SIZE / MiB);
-        return;
+        return false;
     }
 
     uuidstr = object_property_get_str(OBJECT(nvdimm), NVDIMM_UUID_PROP,
@@ -82,8 +82,10 @@ void spapr_nvdimm_validate(HotplugHandler *hotplug_dev, NVDIMMDevice *nvdimm,
 
     if (qemu_uuid_is_null(&uuid)) {
         error_setg(errp, "NVDIMM device requires the uuid to be set");
-        return;
+        return false;
     }
+
+    return true;
 }
 
 
diff --git a/include/hw/ppc/spapr_nvdimm.h b/include/hw/ppc/spapr_nvdimm.h
index 3eb344e8e9..b834d82f55 100644
--- a/include/hw/ppc/spapr_nvdimm.h
+++ b/include/hw/ppc/spapr_nvdimm.h
@@ -28,7 +28,7 @@ QEMU_BUILD_BUG_ON(SPAPR_MINIMUM_SCM_BLOCK_SIZE % SPAPR_MEMORY_BLOCK_SIZE);
 int spapr_pmem_dt_populate(SpaprDrc *drc, SpaprMachineState *spapr,
                            void *fdt, int *fdt_start_offset, Error **errp);
 void spapr_dt_persistent_memory(SpaprMachineState *spapr, void *fdt);
-void spapr_nvdimm_validate(HotplugHandler *hotplug_dev, NVDIMMDevice *nvdimm,
+bool spapr_nvdimm_validate(HotplugHandler *hotplug_dev, NVDIMMDevice *nvdimm,
                            uint64_t size, Error **errp);
 void spapr_add_nvdimm(DeviceState *dev, uint64_t slot, Error **errp);
 void spapr_create_nvdimm_dr_connectors(SpaprMachineState *spapr);
-- 
2.26.2

[PULL 14/20] spapr: Add a return value to spapr_check_pagesize()

[David Gibson]

From: Greg Kurz <groug@kaod.org>

As recommended in "qapi/error.h", return true on success and false on
failure. This allows to reduce error propagation overhead in the callers.

Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <20200914123505.612812-14-groug@kaod.org>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 hw/ppc/spapr.c         | 4 +---
 hw/ppc/spapr_caps.c    | 7 +++++--
 include/hw/ppc/spapr.h | 2 +-
 3 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 7f3a620d41..4256794f3b 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -3490,9 +3490,7 @@ static void spapr_memory_pre_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
     memdev = object_property_get_link(OBJECT(dimm), PC_DIMM_MEMDEV_PROP,
                                       &error_abort);
     pagesize = host_memory_backend_pagesize(MEMORY_BACKEND(memdev));
-    spapr_check_pagesize(spapr, pagesize, &local_err);
-    if (local_err) {
-        error_propagate(errp, local_err);
+    if (!spapr_check_pagesize(spapr, pagesize, errp)) {
         return;
     }
 
diff --git a/hw/ppc/spapr_caps.c b/hw/ppc/spapr_caps.c
index 10a80a8159..9341e9782a 100644
--- a/hw/ppc/spapr_caps.c
+++ b/hw/ppc/spapr_caps.c
@@ -310,13 +310,13 @@ static void cap_safe_indirect_branch_apply(SpaprMachineState *spapr,
 
 #define VALUE_DESC_TRISTATE     " (broken, workaround, fixed)"
 
-void spapr_check_pagesize(SpaprMachineState *spapr, hwaddr pagesize,
+bool spapr_check_pagesize(SpaprMachineState *spapr, hwaddr pagesize,
                           Error **errp)
 {
     hwaddr maxpagesize = (1ULL << spapr->eff.caps[SPAPR_CAP_HPT_MAXPAGESIZE]);
 
     if (!kvmppc_hpt_needs_host_contiguous_pages()) {
-        return;
+        return true;
     }
 
     if (maxpagesize > pagesize) {
@@ -324,7 +324,10 @@ void spapr_check_pagesize(SpaprMachineState *spapr, hwaddr pagesize,
                    "Can't support %"HWADDR_PRIu" kiB guest pages with %"
                    HWADDR_PRIu" kiB host pages with this KVM implementation",
                    maxpagesize >> 10, pagesize >> 10);
+        return false;
     }
+
+    return true;
 }
 
 static void cap_hpt_maxpagesize_apply(SpaprMachineState *spapr,
diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
index 02f3c29838..bba8736269 100644
--- a/include/hw/ppc/spapr.h
+++ b/include/hw/ppc/spapr.h
@@ -934,7 +934,7 @@ void spapr_caps_cpu_apply(SpaprMachineState *spapr, PowerPCCPU *cpu);
 void spapr_caps_add_properties(SpaprMachineClass *smc);
 int spapr_caps_post_migration(SpaprMachineState *spapr);
 
-void spapr_check_pagesize(SpaprMachineState *spapr, hwaddr pagesize,
+bool spapr_check_pagesize(SpaprMachineState *spapr, hwaddr pagesize,
                           Error **errp);
 /*
  * XIVE definitions
-- 
2.26.2

[PULL 15/20] ppc/pnv: Increase max firmware size

[David Gibson]

From: Cédric Le Goater <clg@kaod.org>

Builds enabling GCOV can be bigger than 4MB and the limit on FSP
systems is 16MB.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Message-Id: <20201002091440.1349326-1-clg@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 hw/ppc/pnv.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/ppc/pnv.c b/hw/ppc/pnv.c
index 6670967e26..d9e52873ea 100644
--- a/hw/ppc/pnv.c
+++ b/hw/ppc/pnv.c
@@ -61,7 +61,7 @@
 
 #define FW_FILE_NAME            "skiboot.lid"
 #define FW_LOAD_ADDR            0x0
-#define FW_MAX_SIZE             (4 * MiB)
+#define FW_MAX_SIZE             (16 * MiB)
 
 #define KERNEL_LOAD_ADDR        0x20000000
 #define KERNEL_MAX_SIZE         (256 * MiB)
-- 
2.26.2

[PULL 16/20] spapr: add spapr_machine_using_legacy_numa() helper

[David Gibson]

From: Daniel Henrique Barboza <danielhb413@gmail.com>

The changes to come to NUMA support are all guest visible. In
theory we could just create a new 5_1 class option flag to
avoid the changes to cascade to 5.1 and under. The reality is that
these changes are only relevant if the machine has more than one
NUMA node. There is no need to change guest behavior that has
been around for years needlesly.

This new helper will be used by the next patches to determine
whether we should retain the (soon to be) legacy NUMA behavior
in the pSeries machine. The new behavior will only be exposed
if:

- machine is pseries-5.2 and newer;
- more than one NUMA node is declared in NUMA state.

Reviewed-by: Greg Kurz <groug@kaod.org>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Message-Id: <20201007172849.302240-2-danielhb413@gmail.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 hw/ppc/spapr.c         | 12 ++++++++++++
 include/hw/ppc/spapr.h |  2 ++
 2 files changed, 14 insertions(+)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 4256794f3b..63315f2d0f 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -294,6 +294,15 @@ static hwaddr spapr_node0_size(MachineState *machine)
     return machine->ram_size;
 }
 
+bool spapr_machine_using_legacy_numa(SpaprMachineState *spapr)
+{
+    MachineState *machine = MACHINE(spapr);
+    SpaprMachineClass *smc = SPAPR_MACHINE_GET_CLASS(machine);
+
+    return smc->pre_5_2_numa_associativity ||
+           machine->numa_state->num_nodes <= 1;
+}
+
 static void add_str(GString *s, const gchar *s1)
 {
     g_string_append_len(s, s1, strlen(s1) + 1);
@@ -4519,8 +4528,11 @@ DEFINE_SPAPR_MACHINE(5_2, "5.2", true);
  */
 static void spapr_machine_5_1_class_options(MachineClass *mc)
 {
+    SpaprMachineClass *smc = SPAPR_MACHINE_CLASS(mc);
+
     spapr_machine_5_2_class_options(mc);
     compat_props_add(mc->compat_props, hw_compat_5_1, hw_compat_5_1_len);
+    smc->pre_5_2_numa_associativity = true;
 }
 
 DEFINE_SPAPR_MACHINE(5_1, "5.1", false);
diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
index bba8736269..bb47896f17 100644
--- a/include/hw/ppc/spapr.h
+++ b/include/hw/ppc/spapr.h
@@ -138,6 +138,7 @@ struct SpaprMachineClass {
     bool smp_threads_vsmt; /* set VSMT to smp_threads by default */
     hwaddr rma_limit;          /* clamp the RMA to this size */
     bool pre_5_1_assoc_refpoints;
+    bool pre_5_2_numa_associativity;
 
     void (*phb_placement)(SpaprMachineState *spapr, uint32_t index,
                           uint64_t *buid, hwaddr *pio, 
@@ -853,6 +854,7 @@ int spapr_max_server_number(SpaprMachineState *spapr);
 void spapr_store_hpte(PowerPCCPU *cpu, hwaddr ptex,
                       uint64_t pte0, uint64_t pte1);
 void spapr_mce_req_event(PowerPCCPU *cpu, bool recovered);
+bool spapr_machine_using_legacy_numa(SpaprMachineState *spapr);
 
 /* DRC callbacks. */
 void spapr_core_release(DeviceState *dev);
-- 
2.26.2

[PULL 17/20] spapr_numa: forbid asymmetrical NUMA setups

[David Gibson]

From: Daniel Henrique Barboza <danielhb413@gmail.com>

The pSeries machine does not support asymmetrical NUMA
configurations. This doesn't make much of a different
since we're not using user input for pSeries NUMA setup,
but this will change in the next patches.

To avoid breaking existing setups, gate this change by
checking for legacy NUMA support.

Reviewed-by: Greg Kurz <groug@kaod.org>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Message-Id: <20201007172849.302240-3-danielhb413@gmail.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 hw/ppc/spapr_numa.c | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/hw/ppc/spapr_numa.c b/hw/ppc/spapr_numa.c
index 64fe567f5d..fe395e80a3 100644
--- a/hw/ppc/spapr_numa.c
+++ b/hw/ppc/spapr_numa.c
@@ -19,6 +19,24 @@
 /* Moved from hw/ppc/spapr_pci_nvlink2.c */
 #define SPAPR_GPU_NUMA_ID           (cpu_to_be32(1))
 
+static bool spapr_numa_is_symmetrical(MachineState *ms)
+{
+    int src, dst;
+    int nb_numa_nodes = ms->numa_state->num_nodes;
+    NodeInfo *numa_info = ms->numa_state->nodes;
+
+    for (src = 0; src < nb_numa_nodes; src++) {
+        for (dst = src; dst < nb_numa_nodes; dst++) {
+            if (numa_info[src].distance[dst] !=
+                numa_info[dst].distance[src]) {
+                return false;
+            }
+        }
+    }
+
+    return true;
+}
+
 void spapr_numa_associativity_init(SpaprMachineState *spapr,
                                    MachineState *machine)
 {
@@ -61,6 +79,22 @@ void spapr_numa_associativity_init(SpaprMachineState *spapr,
 
         spapr->numa_assoc_array[i][MAX_DISTANCE_REF_POINTS] = cpu_to_be32(i);
     }
+
+    /*
+     * Legacy NUMA guests (pseries-5.1 and older, or guests with only
+     * 1 NUMA node) will not benefit from anything we're going to do
+     * after this point.
+     */
+    if (spapr_machine_using_legacy_numa(spapr)) {
+        return;
+    }
+
+    if (!spapr_numa_is_symmetrical(machine)) {
+        error_report("Asymmetrical NUMA topologies aren't supported "
+                     "in the pSeries machine");
+        exit(EXIT_FAILURE);
+    }
+
 }
 
 void spapr_numa_write_associativity_dt(SpaprMachineState *spapr, void *fdt,
-- 
2.26.2

[PULL 18/20] spapr_numa: change reference-points and maxdomain settings

[David Gibson]

From: Daniel Henrique Barboza <danielhb413@gmail.com>

This is the first guest visible change introduced in
spapr_numa.c. The previous settings of both reference-points
and maxdomains were too restrictive, but enough for the
existing associativity we're setting in the resources.

We'll change that in the following patches, populating the
associativity arrays based on user input. For those changes
to be effective, reference-points and maxdomains must be
more flexible. After this patch, we'll have 4 distinct
levels of NUMA (0x4, 0x3, 0x2, 0x1) and maxdomains will
allow for any type of configuration the user intends to
do - under the scope and limitations of PAPR itself, of
course.

Reviewed-by: Greg Kurz <groug@kaod.org>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Message-Id: <20201007172849.302240-4-danielhb413@gmail.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 hw/ppc/spapr_numa.c | 43 +++++++++++++++++++++++++++++++++++--------
 1 file changed, 35 insertions(+), 8 deletions(-)

diff --git a/hw/ppc/spapr_numa.c b/hw/ppc/spapr_numa.c
index fe395e80a3..16badb1f4b 100644
--- a/hw/ppc/spapr_numa.c
+++ b/hw/ppc/spapr_numa.c
@@ -178,24 +178,51 @@ int spapr_numa_write_assoc_lookup_arrays(SpaprMachineState *spapr, void *fdt,
  */
 void spapr_numa_write_rtas_dt(SpaprMachineState *spapr, void *fdt, int rtas)
 {
+    MachineState *ms = MACHINE(spapr);
     SpaprMachineClass *smc = SPAPR_MACHINE_GET_CLASS(spapr);
     uint32_t refpoints[] = {
         cpu_to_be32(0x4),
-        cpu_to_be32(0x4),
+        cpu_to_be32(0x3),
         cpu_to_be32(0x2),
+        cpu_to_be32(0x1),
     };
     uint32_t nr_refpoints = ARRAY_SIZE(refpoints);
-    uint32_t maxdomain = cpu_to_be32(spapr->gpu_numa_id > 1 ? 1 : 0);
+    uint32_t maxdomain = ms->numa_state->num_nodes + spapr->gpu_numa_id;
     uint32_t maxdomains[] = {
         cpu_to_be32(4),
-        maxdomain,
-        maxdomain,
-        maxdomain,
-        cpu_to_be32(spapr->gpu_numa_id),
+        cpu_to_be32(maxdomain),
+        cpu_to_be32(maxdomain),
+        cpu_to_be32(maxdomain),
+        cpu_to_be32(maxdomain)
     };
 
-    if (smc->pre_5_1_assoc_refpoints) {
-        nr_refpoints = 2;
+    if (spapr_machine_using_legacy_numa(spapr)) {
+        uint32_t legacy_refpoints[] = {
+            cpu_to_be32(0x4),
+            cpu_to_be32(0x4),
+            cpu_to_be32(0x2),
+        };
+        uint32_t legacy_maxdomain = spapr->gpu_numa_id > 1 ? 1 : 0;
+        uint32_t legacy_maxdomains[] = {
+            cpu_to_be32(4),
+            cpu_to_be32(legacy_maxdomain),
+            cpu_to_be32(legacy_maxdomain),
+            cpu_to_be32(legacy_maxdomain),
+            cpu_to_be32(spapr->gpu_numa_id),
+        };
+
+        G_STATIC_ASSERT(sizeof(legacy_refpoints) <= sizeof(refpoints));
+        G_STATIC_ASSERT(sizeof(legacy_maxdomains) <= sizeof(maxdomains));
+
+        nr_refpoints = 3;
+
+        memcpy(refpoints, legacy_refpoints, sizeof(legacy_refpoints));
+        memcpy(maxdomains, legacy_maxdomains, sizeof(legacy_maxdomains));
+
+        /* pseries-5.0 and older reference-points array is {0x4, 0x4} */
+        if (smc->pre_5_1_assoc_refpoints) {
+            nr_refpoints = 2;
+        }
     }
 
     _FDT(fdt_setprop(fdt, rtas, "ibm,associativity-reference-points",
-- 
2.26.2

[PULL 19/20] spapr_numa: consider user input when defining associativity

[David Gibson]

From: Daniel Henrique Barboza <danielhb413@gmail.com>

A new function called spapr_numa_define_associativity_domains()
is created to calculate the associativity domains and change
the associativity arrays considering user input. This is how
the associativity domain between two NUMA nodes A and B is
calculated:

- get the distance D between them

- get the correspondent NUMA level 'n_level' for D. This is done
via a helper called spapr_numa_get_numa_level()

- all associativity arrays were initialized with their own
numa_ids, and we're calculating the distance in node_id ascending
order, starting from node id 0 (the first node retrieved by
numa_state). This will have a cascade effect in the algorithm because
the associativity domains that node 0 defines will be carried over to
other nodes, and node 1 associativities will be carried over after
taking node 0 associativities into account, and so on. This
happens because we'll assign assoc_src as the associativity domain
of dst as well, for all NUMA levels beyond and including n_level.

The PPC kernel expects the associativity domains of the first node
(node id 0) to be always 0 [1], and this algorithm will grant that
by default.

Ultimately, all of this results in a best effort approximation for
the actual NUMA distances the user input in the command line. Given
the nature of how PAPR itself interprets NUMA distances versus the
expectations risen by how ACPI SLIT works, there might be better
algorithms but, in the end, it'll also result in another way to
approximate what the user really wanted.

To keep this commit message no longer than it already is, the next
patch will update the existing documentation in ppc-spapr-numa.rst
with more in depth details and design considerations/drawbacks.

[1] https://lore.kernel.org/linuxppc-dev/5e8fbea3-8faf-0951-172a-b41a2138fbcf@gmail.com/

Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Message-Id: <20201007172849.302240-5-danielhb413@gmail.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 hw/ppc/spapr_numa.c | 110 +++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 109 insertions(+), 1 deletion(-)

diff --git a/hw/ppc/spapr_numa.c b/hw/ppc/spapr_numa.c
index 16badb1f4b..b50796bbe3 100644
--- a/hw/ppc/spapr_numa.c
+++ b/hw/ppc/spapr_numa.c
@@ -37,12 +37,108 @@ static bool spapr_numa_is_symmetrical(MachineState *ms)
     return true;
 }
 
+/*
+ * This function will translate the user distances into
+ * what the kernel understand as possible values: 10
+ * (local distance), 20, 40, 80 and 160, and return the equivalent
+ * NUMA level for each. Current heuristic is:
+ *  - local distance (10) returns numa_level = 0x4, meaning there is
+ *    no rounding for local distance
+ *  - distances between 11 and 30 inclusive -> rounded to 20,
+ *    numa_level = 0x3
+ *  - distances between 31 and 60 inclusive -> rounded to 40,
+ *    numa_level = 0x2
+ *  - distances between 61 and 120 inclusive -> rounded to 80,
+ *    numa_level = 0x1
+ *  - everything above 120 returns numa_level = 0 to indicate that
+ *    there is no match. This will be calculated as disntace = 160
+ *    by the kernel (as of v5.9)
+ */
+static uint8_t spapr_numa_get_numa_level(uint8_t distance)
+{
+    if (distance == 10) {
+        return 0x4;
+    } else if (distance > 11 && distance <= 30) {
+        return 0x3;
+    } else if (distance > 31 && distance <= 60) {
+        return 0x2;
+    } else if (distance > 61 && distance <= 120) {
+        return 0x1;
+    }
+
+    return 0;
+}
+
+static void spapr_numa_define_associativity_domains(SpaprMachineState *spapr)
+{
+    MachineState *ms = MACHINE(spapr);
+    NodeInfo *numa_info = ms->numa_state->nodes;
+    int nb_numa_nodes = ms->numa_state->num_nodes;
+    int src, dst, i;
+
+    for (src = 0; src < nb_numa_nodes; src++) {
+        for (dst = src; dst < nb_numa_nodes; dst++) {
+            /*
+             * This is how the associativity domain between A and B
+             * is calculated:
+             *
+             * - get the distance D between them
+             * - get the correspondent NUMA level 'n_level' for D
+             * - all associativity arrays were initialized with their own
+             * numa_ids, and we're calculating the distance in node_id
+             * ascending order, starting from node id 0 (the first node
+             * retrieved by numa_state). This will have a cascade effect in
+             * the algorithm because the associativity domains that node 0
+             * defines will be carried over to other nodes, and node 1
+             * associativities will be carried over after taking node 0
+             * associativities into account, and so on. This happens because
+             * we'll assign assoc_src as the associativity domain of dst
+             * as well, for all NUMA levels beyond and including n_level.
+             *
+             * The PPC kernel expects the associativity domains of node 0 to
+             * be always 0, and this algorithm will grant that by default.
+             */
+            uint8_t distance = numa_info[src].distance[dst];
+            uint8_t n_level = spapr_numa_get_numa_level(distance);
+            uint32_t assoc_src;
+
+            /*
+             * n_level = 0 means that the distance is greater than our last
+             * rounded value (120). In this case there is no NUMA level match
+             * between src and dst and we can skip the remaining of the loop.
+             *
+             * The Linux kernel will assume that the distance between src and
+             * dst, in this case of no match, is 10 (local distance) doubled
+             * for each NUMA it didn't match. We have MAX_DISTANCE_REF_POINTS
+             * levels (4), so this gives us 10*2*2*2*2 = 160.
+             *
+             * This logic can be seen in the Linux kernel source code, as of
+             * v5.9, in arch/powerpc/mm/numa.c, function __node_distance().
+             */
+            if (n_level == 0) {
+                continue;
+            }
+
+            /*
+             * We must assign all assoc_src to dst, starting from n_level
+             * and going up to 0x1.
+             */
+            for (i = n_level; i > 0; i--) {
+                assoc_src = spapr->numa_assoc_array[src][i];
+                spapr->numa_assoc_array[dst][i] = assoc_src;
+            }
+        }
+    }
+
+}
+
 void spapr_numa_associativity_init(SpaprMachineState *spapr,
                                    MachineState *machine)
 {
     SpaprMachineClass *smc = SPAPR_MACHINE_GET_CLASS(spapr);
     int nb_numa_nodes = machine->numa_state->num_nodes;
     int i, j, max_nodes_with_gpus;
+    bool using_legacy_numa = spapr_machine_using_legacy_numa(spapr);
 
     /*
      * For all associativity arrays: first position is the size,
@@ -56,6 +152,17 @@ void spapr_numa_associativity_init(SpaprMachineState *spapr,
     for (i = 0; i < nb_numa_nodes; i++) {
         spapr->numa_assoc_array[i][0] = cpu_to_be32(MAX_DISTANCE_REF_POINTS);
         spapr->numa_assoc_array[i][MAX_DISTANCE_REF_POINTS] = cpu_to_be32(i);
+
+        /*
+         * Fill all associativity domains of non-zero NUMA nodes with
+         * node_id. This is required because the default value (0) is
+         * considered a match with associativity domains of node 0.
+         */
+        if (!using_legacy_numa && i != 0) {
+            for (j = 1; j < MAX_DISTANCE_REF_POINTS; j++) {
+                spapr->numa_assoc_array[i][j] = cpu_to_be32(i);
+            }
+        }
     }
 
     /*
@@ -85,7 +192,7 @@ void spapr_numa_associativity_init(SpaprMachineState *spapr,
      * 1 NUMA node) will not benefit from anything we're going to do
      * after this point.
      */
-    if (spapr_machine_using_legacy_numa(spapr)) {
+    if (using_legacy_numa) {
         return;
     }
 
@@ -95,6 +202,7 @@ void spapr_numa_associativity_init(SpaprMachineState *spapr,
         exit(EXIT_FAILURE);
     }
 
+    spapr_numa_define_associativity_domains(spapr);
 }
 
 void spapr_numa_write_associativity_dt(SpaprMachineState *spapr, void *fdt,
-- 
2.26.2

[PULL 20/20] specs/ppc-spapr-numa: update with new NUMA support

[David Gibson]

From: Daniel Henrique Barboza <danielhb413@gmail.com>

This update provides more in depth information about the
choices and drawbacks of the new NUMA support for the
spapr machine.

Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Message-Id: <20201007172849.302240-6-danielhb413@gmail.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 docs/specs/ppc-spapr-numa.rst | 235 ++++++++++++++++++++++++++++++++--
 1 file changed, 227 insertions(+), 8 deletions(-)

diff --git a/docs/specs/ppc-spapr-numa.rst b/docs/specs/ppc-spapr-numa.rst
index e762038022..5fca2bdd8e 100644
--- a/docs/specs/ppc-spapr-numa.rst
+++ b/docs/specs/ppc-spapr-numa.rst
@@ -158,9 +158,235 @@ kernel tree). This results in the following distances:
 * resources four NUMA levels apart: 160
 
 
-Consequences for QEMU NUMA tuning
+pseries NUMA mechanics
+======================
+
+Starting in QEMU 5.2, the pseries machine considers user input when setting NUMA
+topology of the guest. The overall design is:
+
+* ibm,associativity-reference-points is set to {0x4, 0x3, 0x2, 0x1}, allowing
+  for 4 distinct NUMA distance values based on the NUMA levels
+
+* ibm,max-associativity-domains supports multiple associativity domains in all
+  NUMA levels, granting user flexibility
+
+* ibm,associativity for all resources varies with user input
+
+These changes are only effective for pseries-5.2 and newer machines that are
+created with more than one NUMA node (disconsidering NUMA nodes created by
+the machine itself, e.g. NVLink 2 GPUs). The now legacy support has been
+around for such a long time, with users seeing NUMA distances 10 and 40
+(and 80 if using NVLink2 GPUs), and there is no need to disrupt the
+existing experience of those guests.
+
+To bring the user experience x86 users have when tuning up NUMA, we had
+to operate under the current pseries Linux kernel logic described in
+`How the pseries Linux guest calculates NUMA distances`_. The result
+is that we needed to translate NUMA distance user input to pseries
+Linux kernel input.
+
+Translating user distance to kernel distance
+--------------------------------------------
+
+User input for NUMA distance can vary from 10 to 254. We need to translate
+that to the values that the Linux kernel operates on (10, 20, 40, 80, 160).
+This is how it is being done:
+
+* user distance 11 to 30 will be interpreted as 20
+* user distance 31 to 60 will be interpreted as 40
+* user distance 61 to 120 will be interpreted as 80
+* user distance 121 and beyond will be interpreted as 160
+* user distance 10 stays 10
+
+The reasoning behind this aproximation is to avoid any round up to the local
+distance (10), keeping it exclusive to the 4th NUMA level (which is still
+exclusive to the node_id). All other ranges were chosen under the developer
+discretion of what would be (somewhat) sensible considering the user input.
+Any other strategy can be used here, but in the end the reality is that we'll
+have to accept that a large array of values will be translated to the same
+NUMA topology in the guest, e.g. this user input:
+
+::
+
+      0   1   2
+  0  10  31 120
+  1  31  10  30
+  2 120  30  10
+
+And this other user input:
+
+::
+
+      0   1   2
+  0  10  60  61
+  1  60  10  11
+  2  61  11  10
+
+Will both be translated to the same values internally:
+
+::
+
+      0   1   2
+  0  10  40  80
+  1  40  10  20
+  2  80  20  10
+
+Users are encouraged to use only the kernel values in the NUMA definition to
+avoid being taken by surprise with that the guest is actually seeing in the
+topology. There are enough potential surprises that are inherent to the
+associativity domain assignment process, discussed below.
+
+
+How associativity domains are assigned
+--------------------------------------
+
+LOPAPR allows more than one associativity array (or 'string') per allocated
+resource. This would be used to represent that the resource has multiple
+connections with the board, and then the operational system, when deciding
+NUMA distancing, should consider the associativity information that provides
+the shortest distance.
+
+The spapr implementation does not support multiple associativity arrays per
+resource, neither does the pseries Linux kernel. We'll have to represent the
+NUMA topology using one associativity per resource, which means that choices
+and compromises are going to be made.
+
+Consider the following NUMA topology entered by user input:
+
+::
+
+      0   1   2   3
+  0  10  40  20  40
+  1  40  10  80  40
+  2  20  80  10  20
+  3  40  40  20  10
+
+All the associativity arrays are initialized with NUMA id in all associativity
+domains:
+
+* node 0: 0 0 0 0
+* node 1: 1 1 1 1
+* node 2: 2 2 2 2
+* node 3: 3 3 3 3
+
+
+Honoring just the relative distances of node 0 to every other node, we find the
+NUMA level matches (considering the reference points {0x4, 0x3, 0x2, 0x1}) for
+each distance:
+
+* distance from 0 to 1 is 40 (no match at 0x4 and 0x3, will match
+  at 0x2)
+* distance from 0 to 2 is 20 (no match at 0x4, will match at 0x3)
+* distance from 0 to 3 is 40 (no match at 0x4 and 0x3, will match
+  at 0x2)
+
+We'll copy the associativity domains of node 0 to all other nodes, based on
+the NUMA level matches. Between 0 and 1, a match in 0x2, we'll also copy
+the domains 0x2 and 0x1 from 0 to 1 as well. This will give us:
+
+* node 0: 0 0 0 0
+* node 1: 0 0 1 1
+
+Doing the same to node 2 and node 3, these are the associativity arrays
+after considering all matches with node 0:
+
+* node 0: 0 0 0 0
+* node 1: 0 0 1 1
+* node 2: 0 0 0 2
+* node 3: 0 0 3 3
+
+The distances related to node 0 are accounted for. For node 1, and keeping
+in mind that we don't need to revisit node 0 again, the distance from
+node 1 to 2 is 80, matching at 0x1, and distance from 1 to 3 is 40,
+match in 0x2. Repeating the same logic of copying all domains up to
+the NUMA level match:
+
+* node 0: 0 0 0 0
+* node 1: 1 0 1 1
+* node 2: 1 0 0 2
+* node 3: 1 0 3 3
+
+In the last step we will analyze just nodes 2 and 3. The desired distance
+between 2 and 3 is 20, i.e. a match in 0x3:
+
+* node 0: 0 0 0 0
+* node 1: 1 0 1 1
+* node 2: 1 0 0 2
+* node 3: 1 0 0 3
+
+
+The kernel will read these arrays and will calculate the following NUMA topology for
+the guest:
+
+::
+
+      0   1   2   3
+  0  10  40  20  20
+  1  40  10  40  40
+  2  20  40  10  20
+  3  20  40  20  10
+
+Note that this is not what the user wanted - the desired distance between
+0 and 3 is 40, we calculated it as 20. This is what the current logic and
+implementation constraints of the kernel and QEMU will provide inside the
+LOPAPR specification.
+
+Users are welcome to use this knowledge and experiment with the input to get
+the NUMA topology they want, or as closer as they want. The important thing
+is to keep expectations up to par with what we are capable of provide at this
+moment: an approximation.
+
+Limitations of the implementation
 ---------------------------------
 
+As mentioned above, the pSeries NUMA distance logic is, in fact, a way to approximate
+user choice. The Linux kernel, and PAPR itself, does not provide QEMU with the ways
+to fully map user input to actual NUMA distance the guest will use. These limitations
+creates two notable limitations in our support:
+
+* Asymmetrical topologies aren't supported. We only support NUMA topologies where
+  the distance from node A to B is always the same as B to A. We do not support
+  any A-B pair where the distance back and forth is asymmetric. For example, the
+  following topology isn't supported and the pSeries guest will not boot with this
+  user input:
+
+::
+
+      0   1
+  0  10  40
+  1  20  10
+
+
+* 'non-transitive' topologies will be poorly translated to the guest. This is the
+  kind of topology where the distance from a node A to B is X, B to C is X, but
+  the distance A to C is not X. E.g.:
+
+::
+
+      0   1   2   3
+  0  10  20  20  40
+  1  20  10  80  40
+  2  20  80  10  20
+  3  40  40  20  10
+
+  In the example above, distance 0 to 2 is 20, 2 to 3 is 20, but 0 to 3 is 40.
+  The kernel will always match with the shortest associativity domain possible,
+  and we're attempting to retain the previous established relations between the
+  nodes. This means that a distance equal to 20 between nodes 0 and 2 and the
+  same distance 20 between nodes 2 and 3 will cause the distance between 0 and 3
+  to also be 20.
+
+
+Legacy (5.1 and older) pseries NUMA mechanics
+=============================================
+
+In short, we can summarize the NUMA distances seem in pseries Linux guests, using
+QEMU up to 5.1, as follows:
+
+* local distance, i.e. the distance of the resource to its own NUMA node: 10
+* if it's a NVLink GPU device, distance: 80
+* every other resource, distance: 40
+
 The way the pseries Linux guest calculates NUMA distances has a direct effect
 on what QEMU users can expect when doing NUMA tuning. As of QEMU 5.1, this is
 the default ibm,associativity-reference-points being used in the pseries
@@ -180,12 +406,5 @@ as far as NUMA distance goes:
   to the same third NUMA level, having distance = 40
 * for NVLink GPUs, distance = 80 from everything else
 
-In short, we can summarize the NUMA distances seem in pseries Linux guests, using
-QEMU up to 5.1, as follows:
-
-* local distance, i.e. the distance of the resource to its own NUMA node: 10
-* if it's a NVLink GPU device, distance: 80
-* every other resource, distance: 40
-
 This also means that user input in QEMU command line does not change the
 NUMA distancing inside the guest for the pseries machine.
-- 
2.26.2

Re: [PULL 00/20] ppc-for-5.2 queue 20201009

[Peter Maydell]

On Fri, 9 Oct 2020 at 11:20, David Gibson <david@gibson.dropbear.id.au> wrote:
>
> The following changes since commit 497d415d76b9f59fcae27f22df1ca2c3fa4df64e:
>
>   Merge remote-tracking branch 'remotes/pmaydell/tags/pull-target-arm-20201008-1' into staging (2020-10-08 21:41:20 +0100)
>
> are available in the Git repository at:
>
>   git://github.com/dgibson/qemu.git tags/ppc-for-5.2-20201009
>
> for you to fetch changes up to 307e7a34dc474c050f345eeb519d957a42f10c77:
>
>   specs/ppc-spapr-numa: update with new NUMA support (2020-10-09 15:06:14 +1100)
>
> ----------------------------------------------------------------
> ppc patch queue 2020-10-09
>
> Here's the next set of ppc related patches for qemu-5.2.  There are
> two main things here:
>
> * Cleanups to error handling in spapr from Greg Kurz
> * Improvements to NUMA handling for spapr from Daniel Barboza
>
> There are also a handful of other bugfixes.


Applied, thanks.

Please update the changelog at https://wiki.qemu.org/ChangeLog/5.2
for any user-visible changes.

-- PMM