diff options
Diffstat (limited to 'arch/x86/xen/enlighten.c')
-rw-r--r-- | arch/x86/xen/enlighten.c | 50 |
1 files changed, 46 insertions, 4 deletions
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c index 46957ead3060..11d6fb4e8483 100644 --- a/arch/x86/xen/enlighten.c +++ b/arch/x86/xen/enlighten.c @@ -483,6 +483,7 @@ static void set_aliased_prot(void *v, pgprot_t prot) pte_t pte; unsigned long pfn; struct page *page; + unsigned char dummy; ptep = lookup_address((unsigned long)v, &level); BUG_ON(ptep == NULL); @@ -492,6 +493,32 @@ static void set_aliased_prot(void *v, pgprot_t prot) pte = pfn_pte(pfn, prot); + /* + * Careful: update_va_mapping() will fail if the virtual address + * we're poking isn't populated in the page tables. We don't + * need to worry about the direct map (that's always in the page + * tables), but we need to be careful about vmap space. In + * particular, the top level page table can lazily propagate + * entries between processes, so if we've switched mms since we + * vmapped the target in the first place, we might not have the + * top-level page table entry populated. + * + * We disable preemption because we want the same mm active when + * we probe the target and when we issue the hypercall. We'll + * have the same nominal mm, but if we're a kernel thread, lazy + * mm dropping could change our pgd. + * + * Out of an abundance of caution, this uses __get_user() to fault + * in the target address just in case there's some obscure case + * in which the target address isn't readable. + */ + + preempt_disable(); + + pagefault_disable(); /* Avoid warnings due to being atomic. */ + __get_user(dummy, (unsigned char __user __force *)v); + pagefault_enable(); + if (HYPERVISOR_update_va_mapping((unsigned long)v, pte, 0)) BUG(); @@ -503,6 +530,8 @@ static void set_aliased_prot(void *v, pgprot_t prot) BUG(); } else kmap_flush_unused(); + + preempt_enable(); } static void xen_alloc_ldt(struct desc_struct *ldt, unsigned entries) @@ -510,6 +539,17 @@ static void xen_alloc_ldt(struct desc_struct *ldt, unsigned entries) const unsigned entries_per_page = PAGE_SIZE / LDT_ENTRY_SIZE; int i; + /* + * We need to mark the all aliases of the LDT pages RO. We + * don't need to call vm_flush_aliases(), though, since that's + * only responsible for flushing aliases out the TLBs, not the + * page tables, and Xen will flush the TLB for us if needed. + * + * To avoid confusing future readers: none of this is necessary + * to load the LDT. The hypervisor only checks this when the + * LDT is faulted in due to subsequent descriptor access. + */ + for(i = 0; i < entries; i += entries_per_page) set_aliased_prot(ldt + i, PAGE_KERNEL_RO); } @@ -1181,10 +1221,11 @@ static const struct pv_cpu_ops xen_cpu_ops __initconst = { .read_tscp = native_read_tscp, .iret = xen_iret, - .irq_enable_sysexit = xen_sysexit, #ifdef CONFIG_X86_64 .usergs_sysret32 = xen_sysret32, .usergs_sysret64 = xen_sysret64, +#else + .irq_enable_sysexit = xen_sysexit, #endif .load_tr_desc = paravirt_nop, @@ -1423,7 +1464,7 @@ static void xen_pvh_set_cr_flags(int cpu) return; /* * For BSP, PSE PGE are set in probe_page_size_mask(), for APs - * set them here. For all, OSFXSR OSXMMEXCPT are set in fpu_init. + * set them here. For all, OSFXSR OSXMMEXCPT are set in fpu__init_cpu(). */ if (cpu_has_pse) cr4_set_bits_and_update_boot(X86_CR4_PSE); @@ -1467,6 +1508,7 @@ asmlinkage __visible void __init xen_start_kernel(void) { struct physdev_set_iopl set_iopl; unsigned long initrd_start = 0; + u64 pat; int rc; if (!xen_start_info) @@ -1574,8 +1616,8 @@ asmlinkage __visible void __init xen_start_kernel(void) * Modify the cache mode translation tables to match Xen's PAT * configuration. */ - - pat_init_cache_modes(); + rdmsrl(MSR_IA32_CR_PAT, pat); + pat_init_cache_modes(pat); /* keep using Xen gdt for now; no urgent need to change it */ |