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X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 17 Jul 2025 10:59:19.4744 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: dfac6fb7-d7f1-411f-3ec7-08ddc520faef X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[SATLEXMB04.amd.com] X-MS-Exchange-CrossTenant-AuthSource: SJ1PEPF00001CEB.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: IA1PR12MB6186 +Juergen for late-hwdom bit Hi, On Mon Jun 23, 2025 at 8:28 PM CEST, dmkhn wrote: > From: Denis Mukhin > > Remove the open-coded domain ID 0 and replace it with a call to > get_initial_domain_id(). Ideally we'd be better off replacing it where applicable with is hardware_domain(), or is_control_domain(), or a ORd version of both dependi= ng on what the hardcoded 0 means to do. > > Signed-off-by: Denis Mukhin > --- > Changes since v9: > - new patch > --- > xen/arch/arm/domain_build.c | 4 ++-- > xen/common/domain.c | 6 +++--- > 2 files changed, 5 insertions(+), 5 deletions(-) > > diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c > index b59b56636920..b525d78c608f 100644 > --- a/xen/arch/arm/domain_build.c > +++ b/xen/arch/arm/domain_build.c > @@ -2074,9 +2074,9 @@ void __init create_dom0(void) > if ( !llc_coloring_enabled ) > flags |=3D CDF_directmap; > =20 > - domid =3D domid_alloc(0); > + domid =3D domid_alloc(get_initial_domain_id()); > if ( domid =3D=3D DOMID_INVALID ) > - panic("Error allocating domain ID 0\n"); > + panic("Error allocating domain ID %d\n", get_initial_domain_id()= ); > =20 > dom0 =3D domain_create(domid, &dom0_cfg, flags); > if ( IS_ERR(dom0) ) On arm this is just another level of indirection. It might work as a marker= to know where dom0 is hardcoded, though. So sounds good to me. > diff --git a/xen/common/domain.c b/xen/common/domain.c > index be022c720b13..27575b4610e3 100644 > --- a/xen/common/domain.c > +++ b/xen/common/domain.c > @@ -492,7 +492,7 @@ static int late_hwdom_init(struct domain *d) > struct domain *dom0; > int rv; > =20 > - if ( d !=3D hardware_domain || d->domain_id =3D=3D 0 ) > + if ( d !=3D hardware_domain || d->domain_id =3D=3D get_initial_domai= n_id() ) This is tricky. get_initial_domain_id() is only non-zero in shim-mode. And = in that mode there's no control nor hardware domain (hence why the initial dom= ain id is not zero in that case). > return 0; > =20 > rv =3D xsm_init_hardware_domain(XSM_HOOK, d); > @@ -501,7 +501,7 @@ static int late_hwdom_init(struct domain *d) > =20 > printk("Initialising hardware domain %d\n", hardware_domid); > =20 > - dom0 =3D rcu_lock_domain_by_id(0); > + dom0 =3D rcu_lock_domain_by_id(get_initial_domain_id()); Hmmm. More generally this is probably trying to find the previous hardware domain. Which the caller already has a pointer to.=20 Maybe this would work? ``` -static int late_hwdom_init(struct domain *d) +static int late_hwdom_init(struct domain *d, struct domain *old_hwdom) { #ifdef CONFIG_LATE_HWDOM struct domain *dom0; int rv; - if ( d !=3D hardware_domain || d->domain_id =3D=3D 0 ) + if ( d !=3D hardware_domain || !old_hwdom ) return 0; rv =3D xsm_init_hardware_domain(XSM_HOOK, d); @@ -493,8 +493,6 @@ static int late_hwdom_init(struct domain *d) printk("Initialising hardware domain %d\n", hardware_domid); - dom0 =3D rcu_lock_domain_by_id(0); - ASSERT(dom0 !=3D NULL); /* * Hardware resource ranges for domain 0 have been set up from * various sources intended to restrict the hardware domain's @@ -512,11 +510,9 @@ static int late_hwdom_init(struct domain *d) #ifdef CONFIG_X86 rangeset_swap(d->arch.ioport_caps, dom0->arch.ioport_caps); setup_io_bitmap(d); - setup_io_bitmap(dom0); + setup_io_bitmap(old_hwdom); #endif - rcu_unlock_domain(dom0); - iommu_hwdom_init(d); return rv; @@ -967,7 +963,7 @@ struct domain *domain_create(domid_t domid, if ( (err =3D sched_init_domain(d, config->cpupool_id)) !=3D 0 ) goto fail; - if ( (err =3D late_hwdom_init(d)) !=3D 0 ) + if ( (err =3D late_hwdom_init(d, old_hwdom)) !=3D 0 ) goto fail; ``` Juergen, do you have any thoughts about this? > ASSERT(dom0 !=3D NULL); > /* > * Hardware resource ranges for domain 0 have been set up from > @@ -2479,7 +2479,7 @@ domid_t domid_alloc(domid_t domid) > if ( domid =3D=3D DOMID_FIRST_RESERVED ) > domid =3D find_next_zero_bit(domid_bitmap, > DOMID_FIRST_RESERVED, > - 1); > + get_initial_domain_id() + 1); IMO, this should be either 1 (for defence in depth against using zero) or 0= . There's nothing special with any other initial domain ids. > #endif > =20 > if ( domid < DOMID_FIRST_RESERVED ) Cheers, Alejandro