[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] x86/mm: Skip the hypervisor range when walking PGD
On 11/05/15 10:56, Boris Ostrovsky wrote: > The range between 0xffff800000000000 and 0xffff87ffffffffff is reserved > for hypervisor and therefore we should not try to follow PGD's indexes > corresponding to those addresses. > > While this has alsways been a problem, with commit e1a58320a38d ("x86/mm: > Warn on W^X mappings") ptdump_walk_pgd_level_core() can now be called > during boot, causing a PV Xen guest to crash. > > Reported-by: Sander Eikelenboom <linux@xxxxxxxxxxxxxx> > Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> > --- > arch/x86/mm/dump_pagetables.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c > index 1bf417e..756c921 100644 > --- a/arch/x86/mm/dump_pagetables.c > +++ b/arch/x86/mm/dump_pagetables.c > @@ -362,8 +362,13 @@ static void ptdump_walk_pgd_level_core(struct seq_file > *m, pgd_t *pgd, > bool checkwx) > { > #ifdef CONFIG_X86_64 > +/* ffff800000000000 - ffff87ffffffffff is reserved for hypervisor */ > +#define is_hypervisor_range(idx) (paravirt_enabled() && \ > + (((idx) >= pgd_index(__PAGE_OFFSET) - 16) && \ > + ((idx) < pgd_index(__PAGE_OFFSET)))) > pgd_t *start = (pgd_t *) &init_level4_pgt; > #else > +#define is_hypervisor_range(idx) 0 > pgd_t *start = swapper_pg_dir; > #endif > pgprotval_t prot; > @@ -381,7 +386,7 @@ static void ptdump_walk_pgd_level_core(struct seq_file > *m, pgd_t *pgd, > > for (i = 0; i < PTRS_PER_PGD; i++) { > st.current_address = normalize_addr(i * PGD_LEVEL_MULT); > - if (!pgd_none(*start)) { > + if (!pgd_none(*start) && !is_hypervisor_range(i)) { > if (pgd_large(*start) || !pgd_present(*start)) { > prot = pgd_flags(*start); > note_page(m, &st, __pgprot(prot), 1); > Maybe we could use the max_lines field in the address_markers[] array? We really shouldn't be mapping anything in the hypervisor space even on native. -hpa _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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