From patchwork Fri Jun 24 10:34:33 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jan Beulich X-Patchwork-Id: 9197283 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 7B0226077D for ; Fri, 24 Jun 2016 10:36:28 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 682A4284AA for ; Fri, 24 Jun 2016 10:36:28 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 594B2284AC; Fri, 24 Jun 2016 10:36:28 +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=-4.2 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 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.wl.linuxfoundation.org (Postfix) with ESMTPS id D2F08284AA for ; Fri, 24 Jun 2016 10:36:27 +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 1bGORb-0004l4-8Z; Fri, 24 Jun 2016 10:34:39 +0000 Received: from mail6.bemta6.messagelabs.com ([85.158.143.247]) by lists.xenproject.org with esmtp (Exim 4.84_2) (envelope-from ) id 1bGORZ-0004kY-KN for xen-devel@lists.xenproject.org; Fri, 24 Jun 2016 10:34:37 +0000 Received: from [85.158.143.35] by server-1.bemta-6.messagelabs.com id D8/D3-09256-CBC0D675; Fri, 24 Jun 2016 10:34:36 +0000 X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFtrBIsWRWlGSWpSXmKPExsXS6fjDS3cPT26 4weubghbft0xmcmD0OPzhCksAYxRrZl5SfkUCa8btNzNZC1brVFz8W97AuFuli5GTQ0ggT+Ln hWlsIDavgJ3EiV+t7CC2hIChxL75q4DiHBwsAqoSD3e4gITZBNQl2p5tZwUJiwgYSJw7mgQSZ haYxCSx5ZomiC0sECTx7+BWZojpdhKLvq8Hm8IpYC+x/7U4iMkrICjxd4cwRKedxMxVN1kmMP LMQsjMQpKBsLUkHv66BWVrSyxb+JoZpJxZQFpi+T8OCNNF4s5MRlQVILa/xOyWn4wLGDlWMao XpxaVpRbpGuslFWWmZ5TkJmbm6BoamOnlphYXJ6an5iQmFesl5+duYgSGKAMQ7GDs+Od0iFGS g0lJlHfaopxwIb6k/JTKjMTijPii0pzU4kOMMhwcShK81sCQFxIsSk1PrUjLzAFGC0xagoNHS YQ3EyTNW1yQmFucmQ6ROsWoKCXO+40bKCEAksgozYNrg0XoJUZZKWFeRqBDhHgKUotyM0tQ5V 8xinMwKgnzmoKM58nMK4Gb/gpoMRPQ4rv92SCLSxIRUlINjNYi644eW7OkQTJzmk9ZScae9em 6CddfRv06F9Q7r+jliYiv7uGeE+foJERkXJfYlPT7UXTYoi3xj4v1fs5hXrlfINzQTGr2IWN+ v+UNkZ/5BCbfv35zTs+tCpsLeYsvtS/1jFE5ndb7dDGHyYxSVknRmunnl5+o89h+qlhPg6Hn1 IKvDzLW/ldiKc5INNRiLipOBAAQELxrywIAAA== X-Env-Sender: JBeulich@suse.com X-Msg-Ref: server-10.tower-21.messagelabs.com!1466764474!20553199!1 X-Originating-IP: [137.65.248.74] X-SpamReason: No, hits=0.0 required=7.0 tests= X-StarScan-Received: X-StarScan-Version: 8.46; banners=-,-,- X-VirusChecked: Checked Received: (qmail 24605 invoked from network); 24 Jun 2016 10:34:35 -0000 Received: from prv-mh.provo.novell.com (HELO prv-mh.provo.novell.com) (137.65.248.74) by server-10.tower-21.messagelabs.com with DHE-RSA-AES256-GCM-SHA384 encrypted SMTP; 24 Jun 2016 10:34:35 -0000 Received: from INET-PRV-MTA by prv-mh.provo.novell.com with Novell_GroupWise; Fri, 24 Jun 2016 04:34:33 -0600 Message-Id: <576D28D902000078000F879D@prv-mh.provo.novell.com> X-Mailer: Novell GroupWise Internet Agent 14.2.0 Date: Fri, 24 Jun 2016 04:34:33 -0600 From: "Jan Beulich" To: "xen-devel" References: <576D25DA02000078000F86C2@prv-mh.provo.novell.com> In-Reply-To: <576D25DA02000078000F86C2@prv-mh.provo.novell.com> Mime-Version: 1.0 Cc: Stefano Stabellini , Wei Liu , George Dunlap , Andrew Cooper , Ian Jackson , Tim Deegan , dgdegra@tycho.nsa.gov Subject: [Xen-devel] [PATCH v2 11/11] x86/HVM: serialize trap injecting producer and consumer 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-Virus-Scanned: ClamAV using ClamSMTP Since injection works on a remote vCPU, and since there's no enforcement of the subject vCPU being paused, there's a potential race between the producing and consuming sides. Fix this by leveraging the vector field as synchronization variable. Signed-off-by: Jan Beulich Reviewed-by: Andrew Cooper x86/HVM: serialize trap injecting producer and consumer Since injection works on a remote vCPU, and since there's no enforcement of the subject vCPU being paused, there's a potential race between the producing and consuming sides. Fix this by leveraging the vector field as synchronization variable. Signed-off-by: Jan Beulich Reviewed-by: Andrew Cooper --- a/xen/arch/x86/hvm/control.c +++ b/xen/arch/x86/hvm/control.c @@ -215,14 +215,16 @@ static int inject_trap(struct domain *d, if ( op->vcpuid >= d->max_vcpus || (v = d->vcpu[op->vcpuid]) == NULL ) return -ENOENT; - if ( v->arch.hvm_vcpu.inject_trap.vector != -1 ) + if ( cmpxchg(&v->arch.hvm_vcpu.inject_trap.vector, HVM_TRAP_VECTOR_UNSET, + HVM_TRAP_VECTOR_UPDATING) != HVM_TRAP_VECTOR_UNSET ) return -EBUSY; - v->arch.hvm_vcpu.inject_trap.vector = op->vector; v->arch.hvm_vcpu.inject_trap.type = op->type; v->arch.hvm_vcpu.inject_trap.error_code = op->error_code; v->arch.hvm_vcpu.inject_trap.insn_len = op->insn_len; v->arch.hvm_vcpu.inject_trap.cr2 = op->cr2; + smp_wmb(); + v->arch.hvm_vcpu.inject_trap.vector = op->vector; return 0; } --- a/xen/arch/x86/hvm/hvm.c +++ b/xen/arch/x86/hvm/hvm.c @@ -510,10 +510,11 @@ void hvm_do_resume(struct vcpu *v) } /* Inject pending hw/sw trap */ - if ( v->arch.hvm_vcpu.inject_trap.vector != -1 ) + if ( v->arch.hvm_vcpu.inject_trap.vector >= 0 ) { + smp_rmb(); hvm_inject_trap(&v->arch.hvm_vcpu.inject_trap); - v->arch.hvm_vcpu.inject_trap.vector = -1; + v->arch.hvm_vcpu.inject_trap.vector = HVM_TRAP_VECTOR_UNSET; } } @@ -1508,7 +1509,7 @@ int hvm_vcpu_initialise(struct vcpu *v) (void(*)(unsigned long))hvm_assert_evtchn_irq, (unsigned long)v); - v->arch.hvm_vcpu.inject_trap.vector = -1; + v->arch.hvm_vcpu.inject_trap.vector = HVM_TRAP_VECTOR_UNSET; if ( is_pvh_domain(d) ) { --- a/xen/include/asm-x86/hvm/hvm.h +++ b/xen/include/asm-x86/hvm/hvm.h @@ -78,6 +78,8 @@ enum hvm_intblk { #define HVM_HAP_SUPERPAGE_1GB 0x00000002 struct hvm_trap { +#define HVM_TRAP_VECTOR_UNSET (-1) +#define HVM_TRAP_VECTOR_UPDATING (-2) int16_t vector; uint8_t type; /* X86_EVENTTYPE_* */ uint8_t insn_len; /* Instruction length */ --- a/xen/arch/x86/hvm/control.c +++ b/xen/arch/x86/hvm/control.c @@ -215,14 +215,16 @@ static int inject_trap(struct domain *d, if ( op->vcpuid >= d->max_vcpus || (v = d->vcpu[op->vcpuid]) == NULL ) return -ENOENT; - if ( v->arch.hvm_vcpu.inject_trap.vector != -1 ) + if ( cmpxchg(&v->arch.hvm_vcpu.inject_trap.vector, HVM_TRAP_VECTOR_UNSET, + HVM_TRAP_VECTOR_UPDATING) != HVM_TRAP_VECTOR_UNSET ) return -EBUSY; - v->arch.hvm_vcpu.inject_trap.vector = op->vector; v->arch.hvm_vcpu.inject_trap.type = op->type; v->arch.hvm_vcpu.inject_trap.error_code = op->error_code; v->arch.hvm_vcpu.inject_trap.insn_len = op->insn_len; v->arch.hvm_vcpu.inject_trap.cr2 = op->cr2; + smp_wmb(); + v->arch.hvm_vcpu.inject_trap.vector = op->vector; return 0; } --- a/xen/arch/x86/hvm/hvm.c +++ b/xen/arch/x86/hvm/hvm.c @@ -510,10 +510,11 @@ void hvm_do_resume(struct vcpu *v) } /* Inject pending hw/sw trap */ - if ( v->arch.hvm_vcpu.inject_trap.vector != -1 ) + if ( v->arch.hvm_vcpu.inject_trap.vector >= 0 ) { + smp_rmb(); hvm_inject_trap(&v->arch.hvm_vcpu.inject_trap); - v->arch.hvm_vcpu.inject_trap.vector = -1; + v->arch.hvm_vcpu.inject_trap.vector = HVM_TRAP_VECTOR_UNSET; } } @@ -1508,7 +1509,7 @@ int hvm_vcpu_initialise(struct vcpu *v) (void(*)(unsigned long))hvm_assert_evtchn_irq, (unsigned long)v); - v->arch.hvm_vcpu.inject_trap.vector = -1; + v->arch.hvm_vcpu.inject_trap.vector = HVM_TRAP_VECTOR_UNSET; if ( is_pvh_domain(d) ) { --- a/xen/include/asm-x86/hvm/hvm.h +++ b/xen/include/asm-x86/hvm/hvm.h @@ -78,6 +78,8 @@ enum hvm_intblk { #define HVM_HAP_SUPERPAGE_1GB 0x00000002 struct hvm_trap { +#define HVM_TRAP_VECTOR_UNSET (-1) +#define HVM_TRAP_VECTOR_UPDATING (-2) int16_t vector; uint8_t type; /* X86_EVENTTYPE_* */ uint8_t insn_len; /* Instruction length */