From nobody Tue Oct 28 01:56:29 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) client-ip=208.118.235.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; dkim=fail; spf=pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org Return-Path: Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) by mx.zohomail.com with SMTPS id 1516156494355148.06012377370666; Tue, 16 Jan 2018 18:34:54 -0800 (PST) Received: from localhost ([::1]:55894 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ebdYz-00065E-H7 for importer@patchew.org; Tue, 16 Jan 2018 21:34:53 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45608) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ebdQK-0007rf-In for qemu-devel@nongnu.org; Tue, 16 Jan 2018 21:25:59 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ebdQI-0001Jm-FO for qemu-devel@nongnu.org; Tue, 16 Jan 2018 21:25:56 -0500 Received: from ozlabs.org ([103.22.144.67]:46743) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1ebdQI-0001HH-2i; Tue, 16 Jan 2018 21:25:54 -0500 Received: by ozlabs.org (Postfix, from userid 1007) id 3zLrY73np0z9t2l; Wed, 17 Jan 2018 13:25:45 +1100 (AEDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gibson.dropbear.id.au; s=201602; t=1516155947; bh=I/LlNomLBkB7csa2mexfdzJhoZMlw3AG2LPLtJcFhyw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cPsyV7xOhQ46dpWUQWwMEx+9IoqdBhDJsZQQbO00Onk4FXmJWyaWs0OcX0J661moH k4r8pkx3dB7+HtOU6wufM/WhcKaCPdpFAENpV/WKxCS3O10JYcxDjwTH+jRSaw5fnv OIJBQBsa6a974JGVaRTEBz9sxaO6AqeenDnV1llg= From: David Gibson To: peter.maydell@linaro.org Date: Wed, 17 Jan 2018 13:25:14 +1100 Message-Id: <20180117022525.31767-12-david@gibson.dropbear.id.au> X-Mailer: git-send-email 2.14.3 In-Reply-To: <20180117022525.31767-1-david@gibson.dropbear.id.au> References: <20180117022525.31767-1-david@gibson.dropbear.id.au> X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 103.22.144.67 Subject: [Qemu-devel] [PULL 11/22] target/ppc: Clarify compat mode max_threads value X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: lvivier@redhat.com, surajjs@au1.ibm.com, joserz@linux.vnet.ibm.com, qemu-devel@nongnu.org, groug@kaod.org, qemu-ppc@nongnu.org, David Gibson Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) X-ZohoMail: RDKM_2 RSF_0 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" 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 --- 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 3e528fe91e..e35214bfc3 100644 --- a/hw/ppc/spapr.c +++ b/hw/ppc/spapr.c @@ -345,7 +345,7 @@ static int spapr_fixup_cpu_dt(void *fdt, sPAPRMachineSt= ate *spapr) PowerPCCPU *cpu =3D POWERPC_CPU(cs); DeviceClass *dc =3D DEVICE_GET_CLASS(cs); int index =3D spapr_vcpu_id(cpu); - int compat_smt =3D MIN(smp_threads, ppc_compat_max_threads(cpu)); + int compat_smt =3D MIN(smp_threads, ppc_compat_max_vthreads(cpu)); =20 if ((index % smt) !=3D 0) { continue; @@ -503,7 +503,7 @@ static void spapr_populate_cpu_dt(CPUState *cs, void *f= dt, int offset, size_t page_sizes_prop_size; uint32_t vcpus_per_socket =3D smp_threads * smp_cores; uint32_t pft_size_prop[] =3D {0, cpu_to_be32(spapr->htab_shift)}; - int compat_smt =3D MIN(smp_threads, ppc_compat_max_threads(cpu)); + int compat_smt =3D 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 276b5b52c2..807c906f68 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; =20 static const CompatInfo compat_table[] =3D { @@ -45,28 +54,28 @@ static const CompatInfo compat_table[] =3D { .pcr =3D PCR_COMPAT_3_00 | PCR_COMPAT_2_07 | PCR_COMPAT_2_06 | PCR_COMPAT_2_05 | PCR_TM_DIS | PCR_VSX_DIS, .pcr_level =3D PCR_COMPAT_2_05, - .max_threads =3D 2, + .max_vthreads =3D 2, }, { /* POWER7, ISA2.06 */ .name =3D "power7", .pvr =3D CPU_POWERPC_LOGICAL_2_06, .pcr =3D PCR_COMPAT_3_00 | PCR_COMPAT_2_07 | PCR_COMPAT_2_06 | PCR= _TM_DIS, .pcr_level =3D PCR_COMPAT_2_06, - .max_threads =3D 4, + .max_vthreads =3D 4, }, { .name =3D "power7+", .pvr =3D CPU_POWERPC_LOGICAL_2_06_PLUS, .pcr =3D PCR_COMPAT_3_00 | PCR_COMPAT_2_07 | PCR_COMPAT_2_06 | PCR= _TM_DIS, .pcr_level =3D PCR_COMPAT_2_06, - .max_threads =3D 4, + .max_vthreads =3D 4, }, { /* POWER8, ISA2.07 */ .name =3D "power8", .pvr =3D CPU_POWERPC_LOGICAL_2_07, .pcr =3D PCR_COMPAT_3_00 | PCR_COMPAT_2_07, .pcr_level =3D PCR_COMPAT_2_07, - .max_threads =3D 8, + .max_vthreads =3D 8, }, { /* POWER9, ISA3.00 */ .name =3D "power9", @@ -80,7 +89,7 @@ static const CompatInfo compat_table[] =3D { * confusing if half of the threads disappear from the guest * if it announces it's POWER9 aware at CAS time. */ - .max_threads =3D 8, + .max_vthreads =3D 8, }, }; =20 @@ -192,14 +201,14 @@ void ppc_set_compat_all(uint32_t compat_pvr, Error **= errp) } } =20 -int ppc_compat_max_threads(PowerPCCPU *cpu) +int ppc_compat_max_vthreads(PowerPCCPU *cpu) { const CompatInfo *compat =3D compat_by_pvr(cpu->compat_pvr); int n_threads =3D CPU(cpu)->nr_threads; =20 if (cpu->compat_pvr) { g_assert(compat); - n_threads =3D MIN(n_threads, compat->max_threads); + n_threads =3D MIN(n_threads, compat->max_vthreads); } =20 return n_threads; diff --git a/target/ppc/cpu.h b/target/ppc/cpu.h index a5e49f23e9..dc6820c5eb 100644 --- a/target/ppc/cpu.h +++ b/target/ppc/cpu.h @@ -1395,7 +1395,7 @@ 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); --=20 2.14.3