[Xen-changelog] [qemu-xen master] spapr: Handle Decimal Floating Point (DFP) as an optional capability

[patchbot@xxxxxxx]

commit e4f4fa00ebebe4b2c2f2ec2d27b7a2b77ce1c25f
Author:     David Gibson <david@xxxxxxxxxxxxxxxxxxxxx>
AuthorDate: Mon Dec 11 17:34:30 2017 +1100
Commit:     Michael Roth <mdroth@xxxxxxxxxxxxxxxxxx>
CommitDate: Mon Feb 5 18:53:54 2018 -0600

    spapr: Handle Decimal Floating Point (DFP) as an optional capability
    
    Decimal Floating Point has been available on POWER7 and later (server)
    cpus.  However, it can be disabled on the hypervisor, meaning that it's
    not available to guests.
    
    We currently handle this by conditionally advertising DFP support in the
    device tree depending on whether the guest CPU model supports it - which
    can also depend on what's allowed in the host for -cpu host.  That can lead
    to confusion on migration, since host properties are silently affecting
    guest visible properties.
    
    This patch handles it by treating it as an optional capability for the
    pseries machine type.
    
    Signed-off-by: David Gibson <david@xxxxxxxxxxxxxxxxxxxxx>
    Reviewed-by: Greg Kurz <groug@xxxxxxxx>
    (cherry picked from commit 2d1fb9bc8e6e78931d8e1bfeb0ed7a4d223b0480)
    Signed-off-by: Michael Roth <mdroth@xxxxxxxxxxxxxxxxxx>
---
 hw/ppc/spapr.c         |  7 ++++---
 hw/ppc/spapr_caps.c    | 18 ++++++++++++++++++
 include/hw/ppc/spapr.h |  3 +++
 3 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index f006662..c55ed9e 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -572,7 +572,7 @@ static void spapr_populate_cpu_dt(CPUState *cs, void *fdt, 
int offset,
     /* Advertise DFP (Decimal Floating Point) if available
      *   0 / no property == no DFP
      *   1               == DFP available */
-    if (env->insns_flags2 & PPC2_DFP) {
+    if (spapr_has_cap(spapr, SPAPR_CAP_DFP)) {
         _FDT((fdt_setprop_cell(fdt, offset, "ibm,dfp", 1)));
     }
 
@@ -3680,7 +3680,7 @@ static void spapr_machine_class_init(ObjectClass *oc, 
void *data)
      */
     mc->numa_mem_align_shift = 28;
 
-    smc->default_caps = spapr_caps(SPAPR_CAP_VSX);
+    smc->default_caps = spapr_caps(SPAPR_CAP_VSX | SPAPR_CAP_DFP);
     spapr_caps_add_properties(smc, &error_abort);
 }
 
@@ -3762,7 +3762,8 @@ static void spapr_machine_2_11_class_options(MachineClass 
*mc)
     sPAPRMachineClass *smc = SPAPR_MACHINE_CLASS(mc);
 
     spapr_machine_2_12_class_options(mc);
-    smc->default_caps = spapr_caps(SPAPR_CAP_HTM | SPAPR_CAP_VSX);
+    smc->default_caps = spapr_caps(SPAPR_CAP_HTM | SPAPR_CAP_VSX
+                                   | SPAPR_CAP_DFP);
     SET_MACHINE_COMPAT(mc, SPAPR_COMPAT_2_11);
 }
 
diff --git a/hw/ppc/spapr_caps.c b/hw/ppc/spapr_caps.c
index 7c855c6..9d070a3 100644
--- a/hw/ppc/spapr_caps.c
+++ b/hw/ppc/spapr_caps.c
@@ -70,6 +70,16 @@ static void cap_vsx_allow(sPAPRMachineState *spapr, Error 
**errp)
     }
 }
 
+static void cap_dfp_allow(sPAPRMachineState *spapr, Error **errp)
+{
+    PowerPCCPU *cpu = POWERPC_CPU(first_cpu);
+    CPUPPCState *env = &cpu->env;
+
+    if (!(env->insns_flags2 & PPC2_DFP)) {
+        error_setg(errp, "DFP support not available, try cap-dfp=off");
+    }
+}
+
 static sPAPRCapabilityInfo capability_table[] = {
     {
         .name = "htm",
@@ -85,6 +95,13 @@ static sPAPRCapabilityInfo capability_table[] = {
         .allow = cap_vsx_allow,
         /* TODO: add cap_vsx_disallow */
     },
+    {
+        .name = "dfp",
+        .description = "Allow Decimal Floating Point (DFP)",
+        .flag = SPAPR_CAP_DFP,
+        .allow = cap_dfp_allow,
+        /* TODO: add cap_dfp_disallow */
+    },
 };
 
 static sPAPRCapabilities default_caps_with_cpu(sPAPRMachineState *spapr,
@@ -104,6 +121,7 @@ static sPAPRCapabilities 
default_caps_with_cpu(sPAPRMachineState *spapr,
     if (!ppc_check_compat(cpu, CPU_POWERPC_LOGICAL_2_06,
                           0, spapr->max_compat_pvr)) {
         caps.mask &= ~SPAPR_CAP_VSX;
+        caps.mask &= ~SPAPR_CAP_DFP;
     }
 
     return caps;
diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
index 7765f34..65cab2a 100644
--- a/include/hw/ppc/spapr.h
+++ b/include/hw/ppc/spapr.h
@@ -62,6 +62,9 @@ typedef enum {
 /* Vector Scalar Extensions */
 #define SPAPR_CAP_VSX               0x0000000000000002ULL
 
+/* Decimal Floating Point */
+#define SPAPR_CAP_DFP               0x0000000000000004ULL
+
 typedef struct sPAPRCapabilities sPAPRCapabilities;
 struct sPAPRCapabilities {
     uint64_t mask;
--
generated by git-patchbot for /home/xen/git/qemu-xen.git#master

_______________________________________________
Xen-changelog mailing list
Xen-changelog@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/xen-changelog