[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] x86/pv: Fix construction of 32bit dom0's
>>> On 06.02.19 at 21:41, <andrew.cooper3@xxxxxxxxxx> wrote: > Slightly RFC: > > 1) I've not worked out exactly what the > > v->vcpu_info = (void *)&d->shared_info->compat.vcpu_info[0]; > > line is supposed to be doing and whether it is needed, but it doesn't > appear to matter. It is perhaps another redundant opencoding. Afaict this is just to be independent of the fact that the vcpu_info array is first in struct shared_info. I'd be fine with it getting replaced by a respective BUILD_BUG_ON(), but I'd like to ask that it not be dropped without replacement. > 2) The reported > > Dom0 alloc.: 000000003e800000->000000003ec00000 (240470 pages to be > allocated) > > line changes by 1 page because of the alloc_domheap_page() moving ahead of > the printk(), but I'm fairly sure this is benign. There is a matching > reduction in the length of the constructed m2p which is perhaps less > benign. Well, the M2P of course has to be correctly sized. An off-by-one would likely result in hard to repro bug reports. > @@ -606,23 +598,14 @@ int __init dom0_construct_pv(struct domain *d, > { > maddr_to_page(mpt_alloc)->u.inuse.type_info = PGT_l4_page_table; > l4start = l4tab = __va(mpt_alloc); mpt_alloc += PAGE_SIZE; > + clear_page(l4tab); > + init_xen_l4_slots(l4tab, _mfn(virt_to_mfn(l4start)), > + d, INVALID_MFN, true); > + v->arch.guest_table = pagetable_from_paddr(__pa(l4start)); > } > else > - { > - page = alloc_domheap_page(d, MEMF_no_owner | MEMF_no_scrub); > - if ( !page ) > - panic("Not enough RAM for domain 0 PML4\n"); > - page->u.inuse.type_info = PGT_l4_page_table|PGT_validated|1; > - l4start = l4tab = page_to_virt(page); > - maddr_to_page(mpt_alloc)->u.inuse.type_info = PGT_l3_page_table; > - l3start = __va(mpt_alloc); mpt_alloc += PAGE_SIZE; This one is lost without replacement, but is needed. Commit 7a9d764630 ("x86/32-on-64: adjust Dom0 initial page table layout") specifically introduced it to make sure the guest-perceived top level page table is allocated first (and hence marks the beginning of the boot page tables, so Dom0 can later put all of them into general use). Jan _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxxx https://lists.xenproject.org/mailman/listinfo/xen-devel
|
![]() |
Lists.xenproject.org is hosted with RackSpace, monitoring our |