From patchwork Tue Nov 23 00:50:36 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paolo Bonzini X-Patchwork-Id: 12633281 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6F3D5C433F5 for ; Tue, 23 Nov 2021 00:51:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233465AbhKWAyV (ORCPT ); Mon, 22 Nov 2021 19:54:21 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:20913 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232649AbhKWAxy (ORCPT ); Mon, 22 Nov 2021 19:53:54 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1637628646; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=nu+6S5YnfxWC0/SRUjRUVc13IurCt0G9rMWN4/Et7NY=; b=YG1YlMRQIsa03tOLMl0MCI0U1AQLuHCEXcg2xbNizs1NAIZQzR8jRl7L0Vt75e2q1wTRAP TW1njEjoqZL+yXsBikAZc7gDSfYpfKJyxid9guYuMrWRZSXGQFrHxA6vOHwejdXV8REcSs qvrL2NcXCt1GhPgyp134+y2uMY+Ckds= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-506-dxm3XyURPRibvZF_EtCEqg-1; Mon, 22 Nov 2021 19:50:43 -0500 X-MC-Unique: dxm3XyURPRibvZF_EtCEqg-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 8D2651DDF2; Tue, 23 Nov 2021 00:50:42 +0000 (UTC) Received: from virtlab701.virt.lab.eng.bos.redhat.com (virtlab701.virt.lab.eng.bos.redhat.com [10.19.152.228]) by smtp.corp.redhat.com (Postfix) with ESMTP id 3EAC460C13; Tue, 23 Nov 2021 00:50:42 +0000 (UTC) From: Paolo Bonzini To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: pgonda@google.com Subject: [PATCH 12/12] KVM: SEV: accept signals in sev_lock_two_vms Date: Mon, 22 Nov 2021 19:50:36 -0500 Message-Id: <20211123005036.2954379-13-pbonzini@redhat.com> In-Reply-To: <20211123005036.2954379-1-pbonzini@redhat.com> References: <20211123005036.2954379-1-pbonzini@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Generally, kvm->lock is not taken for a long time, but sev_lock_two_vms is different: it takes vCPU locks inside, so userspace can hold it back just by calling a vCPU ioctl. Play it safe and use mutex_lock_killable. Signed-off-by: Paolo Bonzini --- arch/x86/kvm/svm/sev.c | 22 ++++++++++++++++------ 1 file changed, 16 insertions(+), 6 deletions(-) diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index bbbf980c7e40..59727a966f90 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -1547,6 +1547,7 @@ static int sev_lock_two_vms(struct kvm *dst_kvm, struct kvm *src_kvm) { struct kvm_sev_info *dst_sev = &to_kvm_svm(dst_kvm)->sev_info; struct kvm_sev_info *src_sev = &to_kvm_svm(src_kvm)->sev_info; + int r = -EBUSY; if (dst_kvm == src_kvm) return -EINVAL; @@ -1558,14 +1559,23 @@ static int sev_lock_two_vms(struct kvm *dst_kvm, struct kvm *src_kvm) if (atomic_cmpxchg_acquire(&dst_sev->migration_in_progress, 0, 1)) return -EBUSY; - if (atomic_cmpxchg_acquire(&src_sev->migration_in_progress, 0, 1)) { - atomic_set_release(&dst_sev->migration_in_progress, 0); - return -EBUSY; - } + if (atomic_cmpxchg_acquire(&src_sev->migration_in_progress, 0, 1)) + goto release_dst; - mutex_lock(&dst_kvm->lock); - mutex_lock(&src_kvm->lock); + r = -EINTR; + if (mutex_lock_killable(&dst_kvm->lock)) + goto release_src; + if (mutex_lock_killable(&src_kvm->lock)) + goto unlock_dst; return 0; + +unlock_dst: + mutex_unlock(&dst_kvm->lock); +release_src: + atomic_set_release(&src_sev->migration_in_progress, 0); +release_dst: + atomic_set_release(&dst_sev->migration_in_progress, 0); + return r; } static void sev_unlock_two_vms(struct kvm *dst_kvm, struct kvm *src_kvm)