From b25ff3cd5a8b561f58b0245115d61cde0572cbdc Mon Sep 17 00:00:00 2001 From: David Gibson Date: Fri, 19 Jan 2018 04:04:56 +0100 Subject: [PATCH 16/21] target/ppc: Clarify compat mode max_threads value RH-Author: David Gibson Message-id: <20180119040458.5629-3-dgibson@redhat.com> Patchwork-id: 78676 O-Subject: [RHEL-7.5 qemu-kvm-rhev PATCH 2/4] target/ppc: Clarify compat mode max_threads value Bugzilla: 1529243 RH-Acked-by: Thomas Huth RH-Acked-by: Laurent Vivier RH-Acked-by: Miroslav Rezanina From: David Gibson We recently had some discussions that were sidetracked for a while, because nearly everyone misapprehended the purpose of the 'max_threads' field in the compatiblity modes table. It's all about guest expectations, not host expectations or support (that's handled elsewhere). In an attempt to avoid a repeat of that confusion, rename the field to 'max_vthreads' and add an explanatory comment. Signed-off-by: David Gibson Reviewed-by: Laurent Vivier Reviewed-by: Greg Kurz Reviewed-by: Jose Ricardo Ziviani (cherry picked from commit abbc124753896f72e3715813ea20dd1924202ff0) Signed-off-by: Miroslav Rezanina Conflicts: hw/ppc/spapr.c Contextual conflict. Signed-off-by: David Gibson --- hw/ppc/spapr.c | 4 ++-- target/ppc/compat.c | 25 +++++++++++++++++-------- target/ppc/cpu.h | 2 +- 3 files changed, 20 insertions(+), 11 deletions(-) diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c index 66227c3..5233366 100644 --- a/hw/ppc/spapr.c +++ b/hw/ppc/spapr.c @@ -345,7 +345,7 @@ static int spapr_fixup_cpu_dt(void *fdt, sPAPRMachineState *spapr) PowerPCCPU *cpu = POWERPC_CPU(cs); DeviceClass *dc = DEVICE_GET_CLASS(cs); int index = ppc_get_vcpu_dt_id(cpu); - int compat_smt = MIN(smp_threads, ppc_compat_max_threads(cpu)); + int compat_smt = MIN(smp_threads, ppc_compat_max_vthreads(cpu)); if ((index % smt) != 0) { continue; @@ -506,7 +506,7 @@ static void spapr_populate_cpu_dt(CPUState *cs, void *fdt, int offset, size_t page_sizes_prop_size; uint32_t vcpus_per_socket = smp_threads * smp_cores; uint32_t pft_size_prop[] = {0, cpu_to_be32(spapr->htab_shift)}; - int compat_smt = MIN(smp_threads, ppc_compat_max_threads(cpu)); + int compat_smt = MIN(smp_threads, ppc_compat_max_vthreads(cpu)); sPAPRDRConnector *drc; int drc_index; uint32_t radix_AP_encodings[PPC_PAGE_SIZES_MAX_SZ]; diff --git a/target/ppc/compat.c b/target/ppc/compat.c index 94ff14a..33658fb 100644 --- a/target/ppc/compat.c +++ b/target/ppc/compat.c @@ -32,7 +32,16 @@ typedef struct { uint32_t pvr; uint64_t pcr; uint64_t pcr_level; - int max_threads; + + /* + * Maximum allowed virtual threads per virtual core + * + * This is to stop older guests getting confused by seeing more + * threads than they think the cpu can support. Usually it's + * equal to the number of threads supported on bare metal + * hardware, but not always (see POWER9). + */ + int max_vthreads; } CompatInfo; static const CompatInfo compat_table[] = { @@ -45,28 +54,28 @@ static const CompatInfo compat_table[] = { .pcr = PCR_COMPAT_3_00 | PCR_COMPAT_2_07 | PCR_COMPAT_2_06 | PCR_COMPAT_2_05 | PCR_TM_DIS | PCR_VSX_DIS, .pcr_level = PCR_COMPAT_2_05, - .max_threads = 2, + .max_vthreads = 2, }, { /* POWER7, ISA2.06 */ .name = "power7", .pvr = CPU_POWERPC_LOGICAL_2_06, .pcr = PCR_COMPAT_3_00 | PCR_COMPAT_2_07 | PCR_COMPAT_2_06 | PCR_TM_DIS, .pcr_level = PCR_COMPAT_2_06, - .max_threads = 4, + .max_vthreads = 4, }, { .name = "power7+", .pvr = CPU_POWERPC_LOGICAL_2_06_PLUS, .pcr = PCR_COMPAT_3_00 | PCR_COMPAT_2_07 | PCR_COMPAT_2_06 | PCR_TM_DIS, .pcr_level = PCR_COMPAT_2_06, - .max_threads = 4, + .max_vthreads = 4, }, { /* POWER8, ISA2.07 */ .name = "power8", .pvr = CPU_POWERPC_LOGICAL_2_07, .pcr = PCR_COMPAT_3_00 | PCR_COMPAT_2_07, .pcr_level = PCR_COMPAT_2_07, - .max_threads = 8, + .max_vthreads = 8, }, { /* POWER9, ISA3.00 */ .name = "power9", @@ -80,7 +89,7 @@ static const CompatInfo compat_table[] = { * confusing if half of the threads disappear from the guest * if it announces it's POWER9 aware at CAS time. */ - .max_threads = 8, + .max_vthreads = 8, }, }; @@ -203,14 +212,14 @@ void ppc_set_compat_all(uint32_t compat_pvr, Error **errp) } } -int ppc_compat_max_threads(PowerPCCPU *cpu) +int ppc_compat_max_vthreads(PowerPCCPU *cpu) { const CompatInfo *compat = compat_by_pvr(cpu->compat_pvr); int n_threads = CPU(cpu)->nr_threads; if (cpu->compat_pvr) { g_assert(compat); - n_threads = MIN(n_threads, compat->max_threads); + n_threads = MIN(n_threads, compat->max_vthreads); } return n_threads; diff --git a/target/ppc/cpu.h b/target/ppc/cpu.h index 6c770a2..9b107e4 100644 --- a/target/ppc/cpu.h +++ b/target/ppc/cpu.h @@ -1374,7 +1374,7 @@ void 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); #endif -int ppc_compat_max_threads(PowerPCCPU *cpu); +int ppc_compat_max_vthreads(PowerPCCPU *cpu); void ppc_compat_add_property(Object *obj, const char *name, uint32_t *compat_pvr, const char *basedesc, Error **errp); -- 1.8.3.1