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spapr: Handle Decimal Floating Point (DFP) as an optional capability

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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@gibson.dropbear.id.au>
Reviewed-by: Greg Kurz <groug@kaod.org>
This commit is contained in:
David Gibson 2017-12-11 17:34:30 +11:00
parent 2938664286
commit 2d1fb9bc8e
3 changed files with 25 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
hw/ppc/spapr.c
View File

@ -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)));
}
@ -3834,7 +3834,7 @@ 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);
}
@ -3916,7 +3916,8 @@ 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);
}

18
hw/ppc/spapr_caps.c
View File

@ -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;

3
include/hw/ppc/spapr.h
View File

@ -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;