From ff6f7e10c6991c676b9a4058e15db5262a6c38f3 Mon Sep 17 00:00:00 2001 From: David Gibson Date: Thu, 7 Dec 2017 17:08:47 +1100 Subject: [PATCH] spapr: Handle VMX/VSX presence as an spapr capability flag 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 Reviewed-by: Greg Kurz (cherry picked from commit 2938664286499c0c30d6e455a7e2e5d3e6c3f63d) Signed-off-by: Michael Roth --- 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 69ddc4bb2348..f006662c5c98 100644 --- a/hw/ppc/spapr.c +++ b/hw/ppc/spapr.c @@ -557,14 +557,16 @@ 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 @@ -3678,7 +3680,7 @@ static void spapr_machine_class_init(ObjectClass *oc, void *data) */ mc->numa_mem_align_shift = 28; - smc->default_caps = spapr_caps(0); + smc->default_caps = spapr_caps(SPAPR_CAP_VSX); spapr_caps_add_properties(smc, &error_abort); } @@ -3760,7 +3762,7 @@ 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); + smc->default_caps = spapr_caps(SPAPR_CAP_HTM | SPAPR_CAP_VSX); SET_MACHINE_COMPAT(mc, SPAPR_COMPAT_2_11); } diff --git a/hw/ppc/spapr_caps.c b/hw/ppc/spapr_caps.c index cad40fe49af5..7c855c67ad40 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 985948b6221f..7765f3439d9b 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;