From patchwork Thu Mar 17 12:13:52 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Durrant X-Patchwork-Id: 8610581 Return-Path: X-Original-To: patchwork-xen-devel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 86167C0553 for ; Thu, 17 Mar 2016 12:27:00 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 4EFFE202FE for ; Thu, 17 Mar 2016 12:26:59 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id F1EF420268 for ; Thu, 17 Mar 2016 12:26:57 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.84_2) (envelope-from ) id 1agWyX-0003eS-6q; Thu, 17 Mar 2016 12:24:25 +0000 Received: from mail6.bemta3.messagelabs.com ([195.245.230.39]) by lists.xenproject.org with esmtp (Exim 4.84_2) (envelope-from ) id 1agWyV-0003dS-OE for xen-devel@lists.xenproject.org; Thu, 17 Mar 2016 12:24:23 +0000 Received: from [85.158.137.68] by server-3.bemta-3.messagelabs.com id D9/1F-03294-7F1AAE65; Thu, 17 Mar 2016 12:24:23 +0000 X-Env-Sender: prvs=877c75a5a=Paul.Durrant@citrix.com X-Msg-Ref: server-7.tower-31.messagelabs.com!1458217460!22281800!2 X-Originating-IP: [66.165.176.89] X-SpamReason: No, hits=0.0 required=7.0 tests=sa_preprocessor: VHJ1c3RlZCBJUDogNjYuMTY1LjE3Ni44OSA9PiAyMDMwMDc=\n, received_headers: No Received headers X-StarScan-Received: X-StarScan-Version: 8.11; banners=-,-,- X-VirusChecked: Checked Received: (qmail 43758 invoked from network); 17 Mar 2016 12:24:22 -0000 Received: from smtp.citrix.com (HELO SMTP.CITRIX.COM) (66.165.176.89) by server-7.tower-31.messagelabs.com with RC4-SHA encrypted SMTP; 17 Mar 2016 12:24:22 -0000 X-IronPort-AV: E=Sophos;i="5.24,350,1454976000"; d="scan'208";a="339878882" From: Paul Durrant To: Date: Thu, 17 Mar 2016 12:13:52 +0000 Message-ID: <1458216832-18378-3-git-send-email-paul.durrant@citrix.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1458216832-18378-1-git-send-email-paul.durrant@citrix.com> References: <1458216832-18378-1-git-send-email-paul.durrant@citrix.com> MIME-Version: 1.0 X-DLP: MIA2 Cc: Wei Liu , Stefano Stabellini , Andrew Cooper , Ian Jackson , Paul Durrant , Jan Beulich , Keir Fraser Subject: [Xen-devel] [PATCH v5 2/2] x86/hvm/viridian: Enable APIC assist enlightenment X-BeenThere: xen-devel@lists.xen.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xen.org Sender: "Xen-devel" X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP This patch adds code to enable the APIC assist enlightenment which, under certain conditions, means that the guest can avoid an EOI of the local APIC and thereby avoid a VMEXIT. Use of the enlightenment by the hypervisor is under control of the toolstack, and is added to the default set. Signed-off-by: Paul Durrant Cc: Ian Jackson Cc: Stefano Stabellini Cc: Wei Liu Cc: Keir Fraser Cc: Jan Beulich Cc: Andrew Cooper --- v4: - Re-worded xl.cfg text and added missing LIBXL_HAVE_ definition v3: - Re-instated read-modify-write for forwards compatibility - Fix a coding style issue v2: - Removed some code duplication and unnecessary read-modify-write operations on the APIC assist word. - Stated in the xl.cfg text that the enlightenment has no effect if posted interrupts are in use. - Added the enlightenment to the default set. --- docs/man/xl.cfg.pod.5 | 12 +++++++- tools/libxl/libxl.h | 6 ++++ tools/libxl/libxl_dom.c | 4 +++ tools/libxl/libxl_types.idl | 1 + xen/arch/x86/hvm/viridian.c | 59 ++++++++++++++++++++++++++++++++++---- xen/arch/x86/hvm/vlapic.c | 58 +++++++++++++++++++++++++++++++++---- xen/include/asm-x86/hvm/viridian.h | 5 ++++ xen/include/public/hvm/params.h | 7 ++++- 8 files changed, 139 insertions(+), 13 deletions(-) diff --git a/docs/man/xl.cfg.pod.5 b/docs/man/xl.cfg.pod.5 index 56b1117..abf638c 100644 --- a/docs/man/xl.cfg.pod.5 +++ b/docs/man/xl.cfg.pod.5 @@ -1484,10 +1484,20 @@ This set incorporates use of hypercalls for remote TLB flushing. This enlightenment may improve performance of Windows guests running on hosts with higher levels of (physical) CPU contention. +=item B + +This set incorporates use of the APIC assist page to avoid EOI of +the local APIC. +This enlightenment may improve performance of guests that make use of +per-vcpu event channel upcall vectors. +Note that this enlightenment will have no effect if the guest is +using APICv posted interrupts. + =item B This is a special value that enables the default set of groups, which -is currently the B, B and B groups. +is currently the B, B, B and B +groups. =item B diff --git a/tools/libxl/libxl.h b/tools/libxl/libxl.h index f9e3ef5..055a7b4 100644 --- a/tools/libxl/libxl.h +++ b/tools/libxl/libxl.h @@ -218,6 +218,12 @@ #define LIBXL_HAVE_SOFT_RESET 1 /* + * LIBXL_HAVE_APIC_ASSIST indicates that the 'apic_assist' value + * is present in the viridian enlightenment enumeration. + */ +#define LIBXL_HAVE_APIC_ASSIST 1 + +/* * libxl ABI compatibility * * The only guarantee which libxl makes regarding ABI compatibility diff --git a/tools/libxl/libxl_dom.c b/tools/libxl/libxl_dom.c index b825b98..09d3bca 100644 --- a/tools/libxl/libxl_dom.c +++ b/tools/libxl/libxl_dom.c @@ -211,6 +211,7 @@ static int hvm_set_viridian_features(libxl__gc *gc, uint32_t domid, libxl_bitmap_set(&enlightenments, LIBXL_VIRIDIAN_ENLIGHTENMENT_BASE); libxl_bitmap_set(&enlightenments, LIBXL_VIRIDIAN_ENLIGHTENMENT_FREQ); libxl_bitmap_set(&enlightenments, LIBXL_VIRIDIAN_ENLIGHTENMENT_TIME_REF_COUNT); + libxl_bitmap_set(&enlightenments, LIBXL_VIRIDIAN_ENLIGHTENMENT_APIC_ASSIST); } libxl_for_each_set_bit(v, info->u.hvm.viridian_enable) { @@ -253,6 +254,9 @@ static int hvm_set_viridian_features(libxl__gc *gc, uint32_t domid, if (libxl_bitmap_test(&enlightenments, LIBXL_VIRIDIAN_ENLIGHTENMENT_HCALL_REMOTE_TLB_FLUSH)) mask |= HVMPV_hcall_remote_tlb_flush; + if (libxl_bitmap_test(&enlightenments, LIBXL_VIRIDIAN_ENLIGHTENMENT_APIC_ASSIST)) + mask |= HVMPV_apic_assist; + if (mask != 0 && xc_hvm_param_set(CTX->xch, domid, diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl index 632c009..e3be957 100644 --- a/tools/libxl/libxl_types.idl +++ b/tools/libxl/libxl_types.idl @@ -221,6 +221,7 @@ libxl_viridian_enlightenment = Enumeration("viridian_enlightenment", [ (2, "time_ref_count"), (3, "reference_tsc"), (4, "hcall_remote_tlb_flush"), + (5, "apic_assist"), ]) libxl_hdtype = Enumeration("hdtype", [ diff --git a/xen/arch/x86/hvm/viridian.c b/xen/arch/x86/hvm/viridian.c index abbca3c..0f548ce 100644 --- a/xen/arch/x86/hvm/viridian.c +++ b/xen/arch/x86/hvm/viridian.c @@ -227,11 +227,6 @@ static void initialize_apic_assist(struct vcpu *v) void *va; /* - * We don't yet make use of the APIC assist page but by setting - * the CPUID3A_MSR_APIC_ACCESS bit in CPUID leaf 40000003 we are duty - * bound to support the MSR. We therefore do just enough to keep windows - * happy. - * * See section 13.3.4.1 of the specification for details of this * enlightenment. */ @@ -255,6 +250,7 @@ static void initialize_apic_assist(struct vcpu *v) *(uint32_t *)va = 0; v->arch.hvm_vcpu.viridian.apic_assist.va = va; + v->arch.hvm_vcpu.viridian.apic_assist.vector = -1; return; fail: @@ -262,6 +258,59 @@ static void initialize_apic_assist(struct vcpu *v) page ? page_to_mfn(page) : INVALID_MFN); } +static uint32_t *get_apic_assist_word(struct vcpu *v) +{ + if ( !(viridian_feature_mask(v->domain) & HVMPV_apic_assist) ) + return NULL; + + return v->arch.hvm_vcpu.viridian.apic_assist.va; +} + +void viridian_start_apic_assist(struct vcpu *v, int vector) +{ + uint32_t *va = get_apic_assist_word(v); + + if ( !va ) + return; + + /* + * If there is already an assist pending then something has gone + * wrong and the VM will most likely hang so force a crash now + * to make the problem clear. + */ + if ( v->arch.hvm_vcpu.viridian.apic_assist.vector >= 0 ) + domain_crash(v->domain); + + v->arch.hvm_vcpu.viridian.apic_assist.vector = vector; + *va |= 1u; +} + +bool_t viridian_complete_apic_assist(struct vcpu *v, int *vector) +{ + uint32_t *va = get_apic_assist_word(v); + + if ( !va ) + return 0; + + if ( *va & 1u ) + return 0; /* Interrupt not yet processed by the guest */ + + *vector = v->arch.hvm_vcpu.viridian.apic_assist.vector; + v->arch.hvm_vcpu.viridian.apic_assist.vector = -1; + return 1; +} + +void viridian_abort_apic_assist(struct vcpu *v) +{ + uint32_t *va = get_apic_assist_word(v); + + if ( !va ) + return; + + *va &= ~1u; + v->arch.hvm_vcpu.viridian.apic_assist.vector = -1; +} + static void teardown_apic_assist(struct vcpu *v) { void *va = v->arch.hvm_vcpu.viridian.apic_assist.va; diff --git a/xen/arch/x86/hvm/vlapic.c b/xen/arch/x86/hvm/vlapic.c index 01a8430..aac4263 100644 --- a/xen/arch/x86/hvm/vlapic.c +++ b/xen/arch/x86/hvm/vlapic.c @@ -38,6 +38,7 @@ #include #include #include +#include #include #include @@ -95,6 +96,18 @@ static int vlapic_find_highest_vector(const void *bitmap) return (fls(word[word_offset*4]) - 1) + (word_offset * 32); } +static int vlapic_find_lowest_vector(const void *bitmap) +{ + const uint32_t *word = bitmap; + unsigned int word_offset; + + /* Work forwards through the bitmap (first 32-bit word in every four). */ + for ( word_offset = 0; word_offset < NR_VECTORS / 32; word_offset++) + if ( word[word_offset * 4] ) + return (ffs(word[word_offset * 4]) - 1) + (word_offset * 32); + + return -1; +} /* * IRR-specific bitmap update & search routines. @@ -1157,7 +1170,7 @@ int vlapic_virtual_intr_delivery_enabled(void) int vlapic_has_pending_irq(struct vcpu *v) { struct vlapic *vlapic = vcpu_vlapic(v); - int irr, isr; + int irr, vector, isr; if ( !vlapic_enabled(vlapic) ) return -1; @@ -1170,10 +1183,27 @@ int vlapic_has_pending_irq(struct vcpu *v) !nestedhvm_vcpu_in_guestmode(v) ) return irr; + /* + * If APIC assist was used then there may have been no EOI so + * we need to clear the requisite bit from the ISR here, before + * comparing with the IRR. + */ + if ( viridian_complete_apic_assist(v, &vector) && + vector != -1 ) + vlapic_clear_vector(vector, &vlapic->regs->data[APIC_ISR]); + isr = vlapic_find_highest_isr(vlapic); isr = (isr != -1) ? isr : 0; if ( (isr & 0xf0) >= (irr & 0xf0) ) + { + /* + * There's already a higher priority vector pending so + * we need to abort any previous APIC assist to ensure there + * is an EOI. + */ + viridian_abort_apic_assist(v); return -1; + } return irr; } @@ -1181,13 +1211,29 @@ int vlapic_has_pending_irq(struct vcpu *v) int vlapic_ack_pending_irq(struct vcpu *v, int vector, bool_t force_ack) { struct vlapic *vlapic = vcpu_vlapic(v); + int isr; - if ( force_ack || !vlapic_virtual_intr_delivery_enabled() ) - { - vlapic_set_vector(vector, &vlapic->regs->data[APIC_ISR]); - vlapic_clear_irr(vector, vlapic); - } + if ( !force_ack && + vlapic_virtual_intr_delivery_enabled() ) + return 1; + + if ( vlapic_test_vector(vector, &vlapic->regs->data[APIC_TMR]) ) + goto done; + + isr = vlapic_find_lowest_vector(&vlapic->regs->data[APIC_ISR]); + if ( isr >= 0 && isr < vector ) + goto done; + + /* + * This vector is edge triggered and there are no lower priority + * vectors pending, so we can use APIC assist to avoid exiting + * for EOI. + */ + viridian_start_apic_assist(v, vector); +done: + vlapic_set_vector(vector, &vlapic->regs->data[APIC_ISR]); + vlapic_clear_irr(vector, vlapic); return 1; } diff --git a/xen/include/asm-x86/hvm/viridian.h b/xen/include/asm-x86/hvm/viridian.h index 19ecc06..336e547 100644 --- a/xen/include/asm-x86/hvm/viridian.h +++ b/xen/include/asm-x86/hvm/viridian.h @@ -24,6 +24,7 @@ struct viridian_vcpu struct { union viridian_apic_assist msr; void *va; + int vector; } apic_assist; }; @@ -122,6 +123,10 @@ void viridian_time_ref_count_thaw(struct domain *d); void viridian_vcpu_deinit(struct vcpu *v); +void viridian_start_apic_assist(struct vcpu *v, int vector); +bool_t viridian_complete_apic_assist(struct vcpu *v, int *vector); +void viridian_abort_apic_assist(struct vcpu *v); + #endif /* __ASM_X86_HVM_VIRIDIAN_H__ */ /* diff --git a/xen/include/public/hvm/params.h b/xen/include/public/hvm/params.h index 73d4718..e69c72c 100644 --- a/xen/include/public/hvm/params.h +++ b/xen/include/public/hvm/params.h @@ -115,12 +115,17 @@ #define _HVMPV_hcall_remote_tlb_flush 4 #define HVMPV_hcall_remote_tlb_flush (1 << _HVMPV_hcall_remote_tlb_flush) +/* Use APIC assist */ +#define _HVMPV_apic_assist 5 +#define HVMPV_apic_assist (1 << _HVMPV_apic_assist) + #define HVMPV_feature_mask \ (HVMPV_base_freq | \ HVMPV_no_freq | \ HVMPV_time_ref_count | \ HVMPV_reference_tsc | \ - HVMPV_hcall_remote_tlb_flush) + HVMPV_hcall_remote_tlb_flush | \ + HVMPV_apic_assist) #endif