From 268880a2fee41c5c1929aac996a3292db41233cb Mon Sep 17 00:00:00 2001

From: David Gibson <dgibson@redhat.com>

Date: Fri, 19 Jan 2018 02:34:39 +0100

Subject: [PATCH 11/21] spapr: Handle VMX/VSX presence as an spapr capability

 flag

RH-Author: David Gibson <dgibson@redhat.com>

Message-id: <20180119023442.28577-5-dgibson@redhat.com>

Patchwork-id: 78671

O-Subject: [RHEL-7.5 qemu-kvm-rhev PATCH 4/7] spapr: Handle VMX/VSX presence as an spapr capability flag

Bugzilla: 1523414

RH-Acked-by: Laurent Vivier <lvivier@redhat.com>

RH-Acked-by: Thomas Huth <thuth@redhat.com>

RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>

From: David Gibson <david@gibson.dropbear.id.au>

We currently have some conditionals in the spapr device tree code to decide

whether or not to advertise the availability of the VMX (aka Altivec) and

VSX vector extensions to the guest, based on whether the guest cpu has

those features.

This can lead to confusion and subtle failures on migration, since it makes

a guest visible change based only on host capabilities.  We now have a

better mechanism for this, in spapr capabilities flags, which explicitly

depend on user options rather than host capabilities.

Rework the advertisement of VSX and VMX based on a new VSX capability.  We

no longer bother with a conditional for VMX support, because every CPU

that's ever been supported by the pseries machine type supports VMX.

NOTE: Some userspace distributions (e.g. RHEL7.4) already rely on

availability of VSX in libc, so using cap-vsx=off may lead to a fatal

SIGILL in init.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

Reviewed-by: Greg Kurz <groug@kaod.org>

(cherry picked from commit 2938664286499c0c30d6e455a7e2e5d3e6c3f63d)

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>

Conflicts:

	hw/ppc/spapr.c

Because of the difference between upstream and downstream machine type

versions.  Adjusted the logic to enable CAP_VSX on all downstream

machine types, as it is for all upstream types.

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1523414

Signed-off-by: David Gibson <dgibson@redhat.com>

---

 hw/ppc/spapr.c         | 20 +++++++++++---------

 hw/ppc/spapr_caps.c    | 25 +++++++++++++++++++++++++

 include/hw/ppc/spapr.h |  3 +++

 3 files changed, 39 insertions(+), 9 deletions(-)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c

index 846b906..0ef2af9 100644

--- a/hw/ppc/spapr.c

+++ b/hw/ppc/spapr.c

@@ -560,14 +560,16 @@ static void spapr_populate_cpu_dt(CPUState *cs, void *fdt, int offset,

                           segs, sizeof(segs))));

     }

-    /* Advertise VMX/VSX (vector extensions) if available

-     *   0 / no property == no vector extensions

+    /* Advertise VSX (vector extensions) if available

      *   1               == VMX / Altivec available

-     *   2               == VSX available */

-    if (env->insns_flags & PPC_ALTIVEC) {

-        uint32_t vmx = (env->insns_flags2 & PPC2_VSX) ? 2 : 1;

-

-        _FDT((fdt_setprop_cell(fdt, offset, "ibm,vmx", vmx)));

+     *   2               == VSX available

+     *

+     * Only CPUs for which we create core types in spapr_cpu_core.c

+     * are possible, and all of those have VMX */

+    if (spapr_has_cap(spapr, SPAPR_CAP_VSX)) {

+        _FDT((fdt_setprop_cell(fdt, offset, "ibm,vmx", 2)));

+    } else {

+        _FDT((fdt_setprop_cell(fdt, offset, "ibm,vmx", 1)));

     }

     /* Advertise DFP (Decimal Floating Point) if available

@@ -3648,7 +3650,7 @@ static void spapr_machine_class_init(ObjectClass *oc, void *data)

     mc->numa_mem_align_shift = 28;

     smc->has_power9_support = true;

-    smc->default_caps = spapr_caps(0);

+    smc->default_caps = spapr_caps(SPAPR_CAP_VSX);

     spapr_caps_add_properties(smc, &error_abort);

 }

@@ -4054,7 +4056,7 @@ static void spapr_machine_rhel740_class_options(MachineClass *mc)

     smc->has_power9_support = false;

     smc->pre_2_10_has_unused_icps = true;

     smc->resize_hpt_default = SPAPR_RESIZE_HPT_DISABLED;

-    smc->default_caps = spapr_caps(SPAPR_CAP_HTM);

+    smc->default_caps = spapr_caps(SPAPR_CAP_HTM | SPAPR_CAP_VSX);

 }

 DEFINE_SPAPR_MACHINE(rhel740, "rhel7.4.0", false);

diff --git a/hw/ppc/spapr_caps.c b/hw/ppc/spapr_caps.c

index 2bdc202..9f901fb 100644

--- a/hw/ppc/spapr_caps.c

+++ b/hw/ppc/spapr_caps.c

@@ -57,6 +57,19 @@ static void cap_htm_allow(sPAPRMachineState *spapr, Error **errp)

     }

 }

+static void cap_vsx_allow(sPAPRMachineState *spapr, Error **errp)

+{

+    PowerPCCPU *cpu = POWERPC_CPU(first_cpu);

+    CPUPPCState *env = &cpu->env;

+

+    /* Allowable CPUs in spapr_cpu_core.c should already have gotten

+     * rid of anything that doesn't do VMX */

+    g_assert(env->insns_flags & PPC_ALTIVEC);

+    if (!(env->insns_flags2 & PPC2_VSX)) {

+        error_setg(errp, "VSX support not available, try cap-vsx=off");

+    }

+}

+

 static sPAPRCapabilityInfo capability_table[] = {

     {

         .name = "htm",

@@ -65,6 +78,13 @@ static sPAPRCapabilityInfo capability_table[] = {

         .allow = cap_htm_allow,

         /* TODO: add cap_htm_disallow */

     },

+    {

+        .name = "vsx",

+        .description = "Allow Vector Scalar Extensions (VSX)",

+        .flag = SPAPR_CAP_VSX,

+        .allow = cap_vsx_allow,

+        /* TODO: add cap_vsx_disallow */

+    },

 };

 static sPAPRCapabilities default_caps_with_cpu(sPAPRMachineState *spapr,

@@ -81,6 +101,11 @@ static sPAPRCapabilities default_caps_with_cpu(sPAPRMachineState *spapr,

         caps.mask &= ~SPAPR_CAP_HTM;

     }

+    if (!ppc_check_compat(cpu, CPU_POWERPC_LOGICAL_2_06,

+                          0, spapr->max_compat_pvr)) {

+        caps.mask &= ~SPAPR_CAP_VSX;

+    }

+

     return caps;

 }

diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h

index f32967a..36f6816 100644

--- a/include/hw/ppc/spapr.h

+++ b/include/hw/ppc/spapr.h

@@ -59,6 +59,9 @@ typedef enum {

 /* Hardware Transactional Memory */

 #define SPAPR_CAP_HTM               0x0000000000000001ULL

+/* Vector Scalar Extensions */

+#define SPAPR_CAP_VSX               0x0000000000000002ULL

+

 typedef struct sPAPRCapabilities sPAPRCapabilities;

 struct sPAPRCapabilities {

     uint64_t mask;

-- 

1.8.3.1