diff options
| -rw-r--r-- | arch/x86/xen/mmu.c | 44 |
1 files changed, 39 insertions, 5 deletions
diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c index f5e86eee4e0e..e8e34938c57d 100644 --- a/arch/x86/xen/mmu.c +++ b/arch/x86/xen/mmu.c @@ -1408,7 +1408,6 @@ static void __xen_write_cr3(bool kernel, unsigned long cr3) xen_mc_callback(set_current_cr3, (void *)cr3); } } - static void xen_write_cr3(unsigned long cr3) { BUG_ON(preemptible()); @@ -1434,6 +1433,45 @@ static void xen_write_cr3(unsigned long cr3) xen_mc_issue(PARAVIRT_LAZY_CPU); /* interrupts restored */ } +#ifdef CONFIG_X86_64 +/* + * At the start of the day - when Xen launches a guest, it has already + * built pagetables for the guest. We diligently look over them + * in xen_setup_kernel_pagetable and graft as appropiate them in the + * init_level4_pgt and its friends. Then when we are happy we load + * the new init_level4_pgt - and continue on. + * + * The generic code starts (start_kernel) and 'init_mem_mapping' sets + * up the rest of the pagetables. When it has completed it loads the cr3. + * N.B. that baremetal would start at 'start_kernel' (and the early + * #PF handler would create bootstrap pagetables) - so we are running + * with the same assumptions as what to do when write_cr3 is executed + * at this point. + * + * Since there are no user-page tables at all, we have two variants + * of xen_write_cr3 - the early bootup (this one), and the late one + * (xen_write_cr3). The reason we have to do that is that in 64-bit + * the Linux kernel and user-space are both in ring 3 while the + * hypervisor is in ring 0. + */ +static void __init xen_write_cr3_init(unsigned long cr3) +{ + BUG_ON(preemptible()); + + xen_mc_batch(); /* disables interrupts */ + + /* Update while interrupts are disabled, so its atomic with + respect to ipis */ + this_cpu_write(xen_cr3, cr3); + + __xen_write_cr3(true, cr3); + + xen_mc_issue(PARAVIRT_LAZY_CPU); /* interrupts restored */ + + pv_mmu_ops.write_cr3 = &xen_write_cr3; +} +#endif + static int xen_pgd_alloc(struct mm_struct *mm) { pgd_t *pgd = mm->pgd; @@ -2102,11 +2140,7 @@ static const struct pv_mmu_ops xen_mmu_ops __initconst = { .write_cr2 = xen_write_cr2, .read_cr3 = xen_read_cr3, -#ifdef CONFIG_X86_32 .write_cr3 = xen_write_cr3_init, -#else - .write_cr3 = xen_write_cr3, -#endif .flush_tlb_user = xen_flush_tlb, .flush_tlb_kernel = xen_flush_tlb, |