[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH 1/3] [not-for-unstable] xen/arm: vgic-v3: Delay the initialization of the domain information
On Tue, 4 Sep 2018, Andrew Cooper wrote: > On 04/09/18 20:35, Julien Grall wrote: > > Hi, > > > > On 09/04/2018 08:21 PM, Julien Grall wrote: > >> A follow-up patch will require to know the number of vCPUs when > >> initializating the vGICv3 domain structure. However this information is > >> not available at domain creation. This is only known once > >> XEN_DOMCTL_max_vpus is called for that domain. > >> > >> In order to get the max vCPUs around, delay the domain part of the vGIC > >> v3 initialization until the first vCPU of the domain is initialized. > >> > >> Signed-off-by: Julien Grall <julien.grall@xxxxxxx> > >> > >> --- > >> > >> Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> > >> > >> This is nasty but I can't find a better way for Xen 4.11 and older. This > >> is not necessary for unstable as the number of vCPUs is known at domain > >> creation. > >> > >> Andrew, I have CCed you to know whether you have a better idea where to > >> place this call on Xen 4.11 and older. > > > > I just noticed that d->max_vcpus is initialized after > > arch_domain_create. So without this patch on Xen 4.12, it will not work. > > > > This is getting nastier because arch_domain_init is the one initialize > > the value returned by dom0_max_vcpus. So I am not entirely sure what > > to do here. > > The positioning after arch_domain_create() is unfortunate, but I > couldn’t manage better with ARM's current behaviour and Jan's insistence > that the allocation of d->vcpu was common. I'd prefer if the dependency > could be broken and the allocation moved earlier. > > One option might be to have an arch_check_domainconfig() (or similar?) > which is called very early on and can sanity check the values, including > cross-checking the vgic and max_vcpus settings? It could even be > responsible for mutating XEN_DOMCTL_CONFIG_GIC_NATIVE into the correct > real value. > > As for your patch here, its a gross hack, but its probably the best > which can be done. *Sighs* If that is what we have to do, it is as ugly as hell, but that is what we'll do. My only suggestion to marginally improve it would be instead of: > + if ( v->vcpu_id == 0 ) > + { > + rc = vgic_v3_real_domain_init(d); > + if ( rc ) > + return rc; > + } to check on d->arch.vgic.rdist_regions instead: if ( d->arch.vgic.rdist_regions == NULL ) { // initialize domain _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxxx https://lists.xenproject.org/mailman/listinfo/xen-devel
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