From patchwork Wed Dec 4 16:20:25 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Roger_Pau_Monn=C3=A9?= X-Patchwork-Id: 11273279 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id D86821593 for ; Wed, 4 Dec 2019 16:21:46 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id B4ACD206DB for ; Wed, 4 Dec 2019 16:21:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=citrix.com header.i=@citrix.com header.b="ROGMLSu8" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B4ACD206DB Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=citrix.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1icXOa-0006vU-TS; Wed, 04 Dec 2019 16:20:56 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1icXOZ-0006v0-RX for xen-devel@lists.xenproject.org; Wed, 04 Dec 2019 16:20:55 +0000 X-Inumbo-ID: 0a218c48-16b2-11ea-99dd-bc764e2007e4 Received: from esa1.hc3370-68.iphmx.com (unknown [216.71.145.142]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id 0a218c48-16b2-11ea-99dd-bc764e2007e4; Wed, 04 Dec 2019 16:20:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=citrix.com; s=securemail; t=1575476452; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=4k3gp64Eb41SEtR8x1EWU9UW9MTRECYJ23Ww9hRv8as=; b=ROGMLSu8duZXfs11+ftMtWjQ+0OllEKHLsE/oCj1WD3OSquLS8u42j43 y4hc7JpONzQkub4m0SCReZRuKOaoBv1DFMkcXKABL91vLMfirkqT8rPQ/ OBhBD9l2m+x0eVo5kFe9tT5Wj5wnrbBS2ZKS3puQaK+XvWfxmT5vdsM3C 8=; Authentication-Results: esa1.hc3370-68.iphmx.com; dkim=none (message not signed) header.i=none; spf=None smtp.pra=roger.pau@citrix.com; spf=Pass smtp.mailfrom=roger.pau@citrix.com; spf=None smtp.helo=postmaster@mail.citrix.com Received-SPF: None (esa1.hc3370-68.iphmx.com: no sender authenticity information available from domain of roger.pau@citrix.com) identity=pra; client-ip=162.221.158.21; receiver=esa1.hc3370-68.iphmx.com; envelope-from="roger.pau@citrix.com"; x-sender="roger.pau@citrix.com"; x-conformance=sidf_compatible Received-SPF: Pass (esa1.hc3370-68.iphmx.com: domain of roger.pau@citrix.com designates 162.221.158.21 as permitted sender) identity=mailfrom; client-ip=162.221.158.21; receiver=esa1.hc3370-68.iphmx.com; envelope-from="roger.pau@citrix.com"; x-sender="roger.pau@citrix.com"; x-conformance=sidf_compatible; x-record-type="v=spf1"; x-record-text="v=spf1 ip4:209.167.231.154 ip4:178.63.86.133 ip4:195.66.111.40/30 ip4:85.115.9.32/28 ip4:199.102.83.4 ip4:192.28.146.160 ip4:192.28.146.107 ip4:216.52.6.88 ip4:216.52.6.188 ip4:162.221.158.21 ip4:162.221.156.83 ip4:168.245.78.127 ~all" Received-SPF: None (esa1.hc3370-68.iphmx.com: no sender authenticity information available from domain of postmaster@mail.citrix.com) identity=helo; client-ip=162.221.158.21; receiver=esa1.hc3370-68.iphmx.com; envelope-from="roger.pau@citrix.com"; x-sender="postmaster@mail.citrix.com"; x-conformance=sidf_compatible IronPort-SDR: M9QDGibj8NxtLJpgf2GP/+LrJpM24eyQmuKYkHKy1LLPe13bSzG21Y91bOka1G44LHPBWdzvkO 36rUuZ0Lzn81k8PKj0TaRqKgTFZNSrzcVUJIwNt1rpm47lfbPDEnYb29Klnnl7TOSNwSaQGLaS M4BRWwmQ48BaRyQg8hiZSuw7GmTa9ea1WKbIcquhT9+CCCjHmhR3h71EbeALbMFxbRnk8GAvvQ Gsrxe9uF66zx5BAcBHvYz5u6eoKoTITsAXg1tQo1mfILmXyD+BELsIAv1oBvVoPL/iJDsgS59n xbw= X-SBRS: 2.7 X-MesageID: 9323390 X-Ironport-Server: esa1.hc3370-68.iphmx.com X-Remote-IP: 162.221.158.21 X-Policy: $RELAYED X-IronPort-AV: E=Sophos;i="5.69,277,1571716800"; d="scan'208";a="9323390" From: Roger Pau Monne To: Date: Wed, 4 Dec 2019 17:20:25 +0100 Message-ID: <20191204162025.37510-5-roger.pau@citrix.com> X-Mailer: git-send-email 2.24.0 In-Reply-To: <20191204162025.37510-1-roger.pau@citrix.com> References: <20191204162025.37510-1-roger.pau@citrix.com> MIME-Version: 1.0 Subject: [Xen-devel] [PATCH v3 4/4] x86/apic: allow enabling x2APIC mode regardless of interrupt remapping X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: Andrew Cooper , Wei Liu , Jan Beulich , Roger Pau Monne Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" x2APIC mode doesn't mandate interrupt remapping, and hence can be enabled independently. This patch enables x2APIC when available, regardless of whether there's interrupt remapping support. This is beneficial specially when running on virtualized environments, since it reduces the amount of vmexits. For example when sending an IPI in xAPIC mode Xen performs at least 3 different accesses to the APIC MMIO region, while when using x2APIC mode a single wrmsr is used. The following numbers are from a lock profiling of a Xen PV shim running a Linux PV kernel with 32 vCPUs and xAPIC mode: (XEN) Global lock flush_lock: addr=ffff82d0804af1c0, lockval=03190319, not locked (XEN) lock:656153(892606463454), block:602183(9495067321843) Average lock time: 1360363ns Average block time: 15767743ns While the following are from the same configuration but with the shim using x2APIC mode: (XEN) Global lock flush_lock: addr=ffff82d0804b01c0, lockval=1adb1adb, not locked (XEN) lock:1841883(1375128998543), block:1658716(10193054890781) Average lock time: 746588ns Average block time: 6145147ns Enabling x2APIC has halved the average lock time, thus reducing contention. Signed-off-by: Roger Pau Monné Reviewed-by: Jan Beulich --- Changes since v2: - Cache the result of iommu_enable_x2apic so it can be used in the lapic suspend/resume paths. Changes since v1: - Fix error paths of iommu_enable_x2apic call in x2apic_bsp_setup. --- NB: should enabling x2APIC without interrupt remapping be limited to running on virtualized environments? The bigger performance benefit is indeed achieved when using x2APIC on virt environments, but I also don't see why we wouldn't want to try using it everywhere where it's supported. --- xen/arch/x86/apic.c | 94 ++++++++++++++++++++++----------------------- 1 file changed, 45 insertions(+), 49 deletions(-) diff --git a/xen/arch/x86/apic.c b/xen/arch/x86/apic.c index a8ee18636f..333115bc88 100644 --- a/xen/arch/x86/apic.c +++ b/xen/arch/x86/apic.c @@ -44,6 +44,8 @@ static bool __read_mostly tdt_enabled; static bool __initdata tdt_enable = true; boolean_param("tdt", tdt_enable); +static bool __read_mostly iommu_x2apic_enabled; + static struct { int active; /* r/w apic fields */ @@ -492,7 +494,8 @@ static void __enable_x2apic(void) static void resume_x2apic(void) { - iommu_enable_x2apic(); + if ( iommu_x2apic_enabled ) + iommu_enable_x2apic(); __enable_x2apic(); } @@ -695,7 +698,8 @@ int lapic_suspend(void) local_irq_save(flags); disable_local_APIC(); - iommu_disable_x2apic(); + if ( iommu_x2apic_enabled ) + iommu_disable_x2apic(); local_irq_restore(flags); return 0; } @@ -860,7 +864,6 @@ void __init x2apic_bsp_setup(void) { struct IO_APIC_route_entry **ioapic_entries = NULL; const char *orig_name; - bool intremap_enabled; if ( !cpu_has_x2apic ) return; @@ -875,56 +878,46 @@ void __init x2apic_bsp_setup(void) printk("x2APIC: Already enabled by BIOS: Ignoring cmdline disable.\n"); } - if ( !iommu_supports_x2apic() ) + if ( iommu_supports_x2apic() ) { - if ( !x2apic_enabled ) + if ( (ioapic_entries = alloc_ioapic_entries()) == NULL ) { - printk("Not enabling x2APIC: depends on IOMMU support\n"); - return; + printk("Allocate ioapic_entries failed\n"); + goto out; } - panic("x2APIC: already enabled by BIOS, but no IOMMU support\n"); - } - - if ( (ioapic_entries = alloc_ioapic_entries()) == NULL ) - { - printk("Allocate ioapic_entries failed\n"); - goto out; - } - if ( save_IO_APIC_setup(ioapic_entries) ) - { - printk("Saving IO-APIC state failed\n"); - goto out; - } + if ( save_IO_APIC_setup(ioapic_entries) ) + { + printk("Saving IO-APIC state failed\n"); + goto out; + } - mask_8259A(); - mask_IO_APIC_setup(ioapic_entries); + mask_8259A(); + mask_IO_APIC_setup(ioapic_entries); - switch ( iommu_enable_x2apic() ) - { - case 0: - intremap_enabled = true; - break; - case -ENXIO: /* ACPI_DMAR_X2APIC_OPT_OUT set */ - if ( !x2apic_enabled ) + switch ( iommu_enable_x2apic() ) { + case 0: + iommu_x2apic_enabled = true; + break; + + case -ENXIO: /* ACPI_DMAR_X2APIC_OPT_OUT set */ + if ( x2apic_enabled ) + panic("IOMMU requests xAPIC mode, but x2APIC already enabled by firmware\n"); + printk("Not enabling x2APIC (upon firmware request)\n"); - intremap_enabled = false; + iommu_x2apic_enabled = false; goto restore_out; + + default: + printk(XENLOG_ERR "Failed to enable Interrupt Remapping\n"); + iommu_x2apic_enabled = false; + break; } - /* fall through */ - default: - if ( x2apic_enabled ) - panic("Interrupt remapping could not be enabled while " - "x2APIC is already enabled by BIOS\n"); - - printk(XENLOG_ERR - "Failed to enable Interrupt Remapping: Will not enable x2APIC.\n"); - intremap_enabled = false; - goto restore_out; - } - force_iommu = 1; + if ( iommu_x2apic_enabled ) + force_iommu = 1; + } if ( !x2apic_enabled ) { @@ -938,13 +931,16 @@ void __init x2apic_bsp_setup(void) printk("Switched to APIC driver %s\n", genapic.name); restore_out: - /* - * NB: do not use raw mode when restoring entries if the iommu has been - * enabled during the process, because the entries need to be translated - * and added to the remapping table in that case. - */ - restore_IO_APIC_setup(ioapic_entries, !intremap_enabled); - unmask_8259A(); + if ( iommu_supports_x2apic() ) + { + /* + * NB: do not use raw mode when restoring entries if the iommu has been + * enabled during the process, because the entries need to be translated + * and added to the remapping table in that case. + */ + restore_IO_APIC_setup(ioapic_entries, !iommu_x2apic_enabled); + unmask_8259A(); + } out: if ( ioapic_entries )