From patchwork Mon Jan 15 07:27:14 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Gibson X-Patchwork-Id: 10163223 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 36C22601C0 for ; Mon, 15 Jan 2018 07:28:23 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 103D12869C for ; Mon, 15 Jan 2018 07:28:23 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 03AE428867; Mon, 15 Jan 2018 07:28:23 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=2.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_HI,T_DKIM_INVALID autolearn=ham version=3.3.1 Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 9D6D92869C for ; Mon, 15 Jan 2018 07:28:21 +0000 (UTC) Received: from localhost ([::1]:44024 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eazBs-0001NJ-8h for patchwork-qemu-devel@patchwork.kernel.org; Mon, 15 Jan 2018 02:28:20 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37881) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eazAy-0000ia-0c for qemu-devel@nongnu.org; Mon, 15 Jan 2018 02:27:25 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eazAw-0000cF-So for qemu-devel@nongnu.org; Mon, 15 Jan 2018 02:27:24 -0500 Received: from ozlabs.org ([2401:3900:2:1::2]:44785) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1eazAw-0000aW-Ep; Mon, 15 Jan 2018 02:27:22 -0500 Received: by ozlabs.org (Postfix, from userid 1007) id 3zKlKy5stzz9sBW; Mon, 15 Jan 2018 18:27:18 +1100 (AEDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gibson.dropbear.id.au; s=201602; t=1516001238; bh=SAz/BEajg7fxKHQnq2zUoWSrOaO1eMb8ytXRbT0SVbM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=kO4ZWG9AKvTVA8JXaF1ii8TUlhZhsnxO0z0aNVLNtJsNbqZm5s/jyIucqAf9Kkbjc hxV1IqMojV0Zy7cBlimkd+PMLj1/R9Y/h67u4oJC1tBPHbvNbtB0E6s9ash0Yvvpks 8DxKTIdaWrDVRfu8toArKLsRqV4Jzk8/FtIt/yhM= From: David Gibson To: groug@kaod.org, joserz@linux.vnet.ibm.com, surajjs@au1.ibm.com, sam.bobroff@au1.ibm.com Date: Mon, 15 Jan 2018 18:27:14 +1100 Message-Id: <20180115072715.25921-2-david@gibson.dropbear.id.au> X-Mailer: git-send-email 2.14.3 In-Reply-To: <20180115072715.25921-1-david@gibson.dropbear.id.au> References: <20180115072715.25921-1-david@gibson.dropbear.id.au> X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 2401:3900:2:1::2 Subject: [Qemu-devel] [PATCH 1/2] 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, qemu-ppc@nongnu.org, qemu-devel@nongnu.org, David Gibson Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP 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, sPAPRMachineState *spapr) PowerPCCPU *cpu = POWERPC_CPU(cs); DeviceClass *dc = DEVICE_GET_CLASS(cs); int index = spapr_vcpu_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; @@ -503,7 +503,7 @@ 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 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; 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, }, }; @@ -192,14 +201,14 @@ 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 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);