From mboxrd@z Thu Jan 1 00:00:00 1970 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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 832BFC87FCA for ; Fri, 8 Aug 2025 02:20:19 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.1073903.1436663 (Exim 4.92) (envelope-from ) id 1ukCiD-00065j-N9; Fri, 08 Aug 2025 02:20:05 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 1073903.1436663; Fri, 08 Aug 2025 02:20:05 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1ukCiD-00065c-IM; Fri, 08 Aug 2025 02:20:05 +0000 Received: by outflank-mailman (input) for mailman id 1073903; Fri, 08 Aug 2025 02:20:05 +0000 Received: from se1-gles-flk1-in.inumbo.com ([94.247.172.50] helo=se1-gles-flk1.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1ukCiC-0005lR-4n for xen-devel@lists.xenproject.org; Fri, 08 Aug 2025 02:20:05 +0000 Received: from mail-10630.protonmail.ch (mail-10630.protonmail.ch [79.135.106.30]) by se1-gles-flk1.inumbo.com (Halon) with ESMTPS id 305b74fd-73fe-11f0-b898-0df219b8e170; Fri, 08 Aug 2025 04:20:02 +0200 (CEST) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: 305b74fd-73fe-11f0-b898-0df219b8e170 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=proton.me; s=protonmail; t=1754619601; x=1754878801; bh=AHtqm8Rq9uACsvnZ5tyK7BjxNs5//7MbFetoXPPO1cc=; h=Date:To:From:Cc:Subject:Message-ID:In-Reply-To:References: Feedback-ID:From:To:Cc:Date:Subject:Reply-To:Feedback-ID: Message-ID:BIMI-Selector; b=f1PscD6lZO/kOSm5kakrnC6D82MYnPHIZr0g91tB5xPWdgrf29WE5a1FTRkesx5HU X8yY+m9DWwph3vtAuI+0AQ5sqy0JcDrYtCwpL0Xrxs+b01cf5aFZzamKgXGoCYqJhB RvCss5FzdMyAl5j2dbOdJJ9naCO3/piwmhz8bHy/F7P2SqaKPm3nD7y8mji3KMNFna FAHK2ARShX9ueyck1b7AwcdiZlbHQaRfuD5sEtPM5GhcCsp6rOMzY+5ssrhGUSlSxj qNNctoSAyx8WoIBmxUbqjrd0bCwTyb0jwV67sH0q0ZEP1PCWQoKun8wOe0VNEP+tod cyd5D1RLJKz7Q== Date: Fri, 08 Aug 2025 02:19:56 +0000 To: xen-devel@lists.xenproject.org From: dmkhn@proton.me Cc: andrew.cooper3@citrix.com, anthony.perard@vates.tech, jbeulich@suse.com, julien@xen.org, michal.orzel@amd.com, roger.pau@citrix.com, sstabellini@kernel.org, dmukhin@ford.com Subject: [PATCH v14 1/4] xen/domain: unify domain ID allocation Message-ID: <20250808021938.669855-2-dmukhin@ford.com> In-Reply-To: <20250808021938.669855-1-dmukhin@ford.com> References: <20250808021938.669855-1-dmukhin@ford.com> Feedback-ID: 123220910:user:proton X-Pm-Message-ID: 19e5857599a554055eca274ea5705df5675bb685 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable From: Denis Mukhin =20 Currently, there are two different domain ID allocation implementations: 1) Sequential IDs allocation in dom0less Arm code based on max_init_domid= ; 2) Sequential IDs allocation in XEN_DOMCTL_createdomain; does not use max_init_domid (both Arm and x86). The domain ID allocation covers dom0 or late hwdom, predefined domains, post-boot domains, excluding Xen system domains (domid >=3D DOMID_FIRST_RESERVED). It makes sense to have a common helper code for such task across architectu= res (Arm and x86) and between dom0less / toolstack domU allocation. Note, fixing dependency on max_init_domid is out of scope of this patch. Wrap the domain ID allocation as an arch-independent function domid_alloc()= in new common/domid.c based on the bitmap. Allocation algorithm: - If an explicit domain ID is provided, verify its availability and use it = if ID is not used; - If DOMID_INVALID is provided, search the range [1..DOMID_FIRST_RESERVED-1= ], starting from the last used ID. Implementation guarantees that two consecutive calls will never return th= e same ID. ID#0 is reserved for the first boot domain (currently, dom0) and excluded from the allocation range. Remove is_free_domid() helper as it is not needed now. No functional change intended. Signed-off-by: Denis Mukhin --- Changes since v13: - fixed panic() formatting in x86's create_dom0() - fixed login in do_domctl() - optimizations in domid_alloc() --- xen/arch/arm/domain_build.c | 7 +- xen/arch/x86/setup.c | 7 +- xen/common/Makefile | 1 + xen/common/device-tree/dom0less-build.c | 15 ++-- xen/common/domain.c | 2 + xen/common/domctl.c | 43 ++--------- xen/common/domid.c | 95 +++++++++++++++++++++++++ xen/include/xen/domain.h | 3 + 8 files changed, 126 insertions(+), 47 deletions(-) create mode 100644 xen/common/domid.c diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c index 463ae4474d30..789f2b9d3ce7 100644 --- a/xen/arch/arm/domain_build.c +++ b/xen/arch/arm/domain_build.c @@ -2050,6 +2050,7 @@ void __init create_dom0(void) .grant_opts =3D XEN_DOMCTL_GRANT_version(opt_gnttab_max_version), }; unsigned int flags =3D CDF_privileged | CDF_hardware; + domid_t domid; int rc; =20 /* The vGIC for DOM0 is exactly emulating the hardware GIC */ @@ -2074,7 +2075,11 @@ void __init create_dom0(void) if ( !llc_coloring_enabled ) flags |=3D CDF_directmap; =20 - dom0 =3D domain_create(0, &dom0_cfg, flags); + domid =3D domid_alloc(0); + if ( domid =3D=3D DOMID_INVALID ) + panic("Error allocating domain ID 0\n"); + + dom0 =3D domain_create(domid, &dom0_cfg, flags); if ( IS_ERR(dom0) ) panic("Error creating domain 0 (rc =3D %ld)\n", PTR_ERR(dom0)); =20 diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c index 1543dd251cc6..398da734c0c5 100644 --- a/xen/arch/x86/setup.c +++ b/xen/arch/x86/setup.c @@ -1047,8 +1047,11 @@ static struct domain *__init create_dom0(struct boot= _info *bi) if ( iommu_enabled ) dom0_cfg.flags |=3D XEN_DOMCTL_CDF_iommu; =20 - /* Create initial domain. Not d0 for pvshim. */ - bd->domid =3D get_initial_domain_id(); + /* Allocate initial domain ID. Not d0 for pvshim. */ + bd->domid =3D domid_alloc(get_initial_domain_id()); + if ( bd->domid =3D=3D DOMID_INVALID ) + panic("Error allocating domain ID %u\n", get_initial_domain_id()); + d =3D domain_create(bd->domid, &dom0_cfg, pv_shim ? 0 : CDF_privileged | CDF_hardware); if ( IS_ERR(d) ) diff --git a/xen/common/Makefile b/xen/common/Makefile index c316957fcb36..0c7d0f5d46e1 100644 --- a/xen/common/Makefile +++ b/xen/common/Makefile @@ -11,6 +11,7 @@ obj-$(filter-out $(CONFIG_X86),$(CONFIG_ACPI)) +=3D devic= e.o obj-$(CONFIG_DEVICE_TREE_PARSE) +=3D device-tree/ obj-$(CONFIG_IOREQ_SERVER) +=3D dm.o obj-y +=3D domain.o +obj-y +=3D domid.o obj-y +=3D event_2l.o obj-y +=3D event_channel.o obj-$(CONFIG_EVTCHN_FIFO) +=3D event_fifo.o diff --git a/xen/common/device-tree/dom0less-build.c b/xen/common/device-tr= ee/dom0less-build.c index 6bb038111de9..f4b6b515d2d2 100644 --- a/xen/common/device-tree/dom0less-build.c +++ b/xen/common/device-tree/dom0less-build.c @@ -833,6 +833,7 @@ void __init create_domUs(void) { struct kernel_info ki =3D KERNEL_INFO_INIT; int rc =3D parse_dom0less_node(node, &ki.bd); + domid_t domid; =20 if ( rc =3D=3D -ENOENT ) continue; @@ -842,13 +843,13 @@ void __init create_domUs(void) if ( (max_init_domid + 1) >=3D DOMID_FIRST_RESERVED ) panic("No more domain IDs available\n"); =20 - /* - * The variable max_init_domid is initialized with zero, so here i= t's - * very important to use the pre-increment operator to call - * domain_create() with a domid > 0. (domid =3D=3D 0 is reserved f= or Dom0) - */ - ki.bd.d =3D domain_create(++max_init_domid, - &ki.bd.create_cfg, ki.bd.create_flags); + domid =3D domid_alloc(DOMID_INVALID); + if ( domid =3D=3D DOMID_INVALID ) + panic("Error allocating ID for domain %s\n", dt_node_name(node= )); + + max_init_domid =3D max(max_init_domid, domid); + + ki.bd.d =3D domain_create(domid, &ki.bd.create_cfg, ki.bd.create_f= lags); if ( IS_ERR(ki.bd.d) ) panic("Error creating domain %s (rc =3D %ld)\n", dt_node_name(node), PTR_ERR(ki.bd.d)); diff --git a/xen/common/domain.c b/xen/common/domain.c index 5241a1629eeb..a7e303253d1a 100644 --- a/xen/common/domain.c +++ b/xen/common/domain.c @@ -692,6 +692,8 @@ static void _domain_destroy(struct domain *d) =20 lock_profile_deregister_struct(LOCKPROF_TYPE_PERDOM, d); =20 + domid_free(d->domain_id); + free_domain_struct(d); } =20 diff --git a/xen/common/domctl.c b/xen/common/domctl.c index f2a7caaf853c..71e712c1f316 100644 --- a/xen/common/domctl.c +++ b/xen/common/domctl.c @@ -51,20 +51,6 @@ static int xenctl_bitmap_to_nodemask(nodemask_t *nodemas= k, MAX_NUMNODES); } =20 -static inline int is_free_domid(domid_t dom) -{ - struct domain *d; - - if ( dom >=3D DOMID_FIRST_RESERVED ) - return 0; - - if ( (d =3D rcu_lock_domain_by_id(dom)) =3D=3D NULL ) - return 1; - - rcu_unlock_domain(d); - return 0; -} - void getdomaininfo(struct domain *d, struct xen_domctl_getdomaininfo *info= ) { struct vcpu *v; @@ -423,36 +409,19 @@ long do_domctl(XEN_GUEST_HANDLE_PARAM(xen_domctl_t) u= _domctl) =20 case XEN_DOMCTL_createdomain: { - domid_t dom; - static domid_t rover =3D 0; + /* NB: ID#0 is reserved, find the first suitable ID instead. */ + domid_t domid =3D domid_alloc(op->domain ?: DOMID_INVALID); =20 - dom =3D op->domain; - if ( (dom > 0) && (dom < DOMID_FIRST_RESERVED) ) + if ( domid =3D=3D DOMID_INVALID ) { ret =3D -EEXIST; - if ( !is_free_domid(dom) ) - break; - } - else - { - for ( dom =3D rover + 1; dom !=3D rover; dom++ ) - { - if ( dom =3D=3D DOMID_FIRST_RESERVED ) - dom =3D 1; - if ( is_free_domid(dom) ) - break; - } - - ret =3D -ENOMEM; - if ( dom =3D=3D rover ) - break; - - rover =3D dom; + break; } =20 - d =3D domain_create(dom, &op->u.createdomain, false); + d =3D domain_create(domid, &op->u.createdomain, false); if ( IS_ERR(d) ) { + domid_free(domid); ret =3D PTR_ERR(d); d =3D NULL; break; diff --git a/xen/common/domid.c b/xen/common/domid.c new file mode 100644 index 000000000000..7839a2885810 --- /dev/null +++ b/xen/common/domid.c @@ -0,0 +1,95 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Domain ID allocator. + * + * Covers dom0 or late hwdom, predefined domains, post-boot domains. + * Excludes system domains (ID >=3D DOMID_FIRST_RESERVED). + * + * Copyright 2025 Ford Motor Company + */ + +#include + +static DEFINE_SPINLOCK(domid_lock); +static DECLARE_BITMAP(domid_bitmap, DOMID_FIRST_RESERVED); + +/* + * Allocate domain ID. + * + * @param domid Domain ID hint: + * - If an explicit domain ID is provided, verify its availability and use= it + * if ID is not used; + * - If DOMID_INVALID is provided, search [1..DOMID_FIRST_RESERVED-1] rang= e, + * starting from the last used ID. Implementation guarantees that two + * consecutive calls will never return the same ID. ID#0 is reserved for + * the first boot domain (currently, dom0) and excluded from the allocat= ion + * range. + * @return Valid domain ID in case of successful allocation, + * DOMID_INVALID - otherwise. + */ +domid_t domid_alloc(domid_t domid) +{ + static domid_t domid_last; + + spin_lock(&domid_lock); + + /* Exact match. */ + if ( domid < DOMID_FIRST_RESERVED ) + { + if ( __test_and_set_bit(domid, domid_bitmap) ) + domid =3D DOMID_INVALID; + } + /* + * Exhaustive search. + * + * Domain ID#0 is reserved for the first boot domain (e.g. control dom= ain) + * and excluded from allocation. + */ + else + { + domid_t num =3D DOMID_FIRST_RESERVED; + + domid =3D find_next_zero_bit(domid_bitmap, num, domid_last + 1); + if ( domid =3D=3D num && domid_last !=3D 0 ) + { + num =3D domid_last + 1; + domid =3D find_next_zero_bit(domid_bitmap, num, 1); + } + + ASSERT(domid <=3D DOMID_FIRST_RESERVED); + if ( domid < num ) + { + __set_bit(domid, domid_bitmap); + domid_last =3D domid; + } + else + domid =3D DOMID_INVALID; + } + + spin_unlock(&domid_lock); + + return domid; +} + +void domid_free(domid_t domid) +{ + int rc; + + ASSERT(domid <=3D DOMID_FIRST_RESERVED); + + spin_lock(&domid_lock); + rc =3D __test_and_clear_bit(domid, domid_bitmap); + spin_unlock(&domid_lock); + + ASSERT(rc); +} + +/* + * Local variables: + * mode: C + * c-file-style: "BSD" + * c-basic-offset: 4 + * tab-width: 4 + * indent-tabs-mode: nil + * End: + */ diff --git a/xen/include/xen/domain.h b/xen/include/xen/domain.h index e10baf2615fd..8aab05ae93c8 100644 --- a/xen/include/xen/domain.h +++ b/xen/include/xen/domain.h @@ -38,6 +38,9 @@ void arch_get_domain_info(const struct domain *d, =20 domid_t get_initial_domain_id(void); =20 +domid_t domid_alloc(domid_t domid); +void domid_free(domid_t domid); + /* CDF_* constant. Internal flags for domain creation. */ /* Is this a privileged domain? */ #define CDF_privileged (1U << 0) --=20 2.34.1