From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757996AbYG0PpU (ORCPT ); Sun, 27 Jul 2008 11:45:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752046AbYG0PpG (ORCPT ); Sun, 27 Jul 2008 11:45:06 -0400 Received: from gw.goop.org ([64.81.55.164]:44164 "EHLO mail.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751224AbYG0PpE (ORCPT ); Sun, 27 Jul 2008 11:45:04 -0400 Message-ID: <488C97FE.2010606@goop.org> Date: Sun, 27 Jul 2008 08:45:02 -0700 From: Jeremy Fitzhardinge User-Agent: Thunderbird 2.0.0.14 (X11/20080501) MIME-Version: 1.0 To: Ingo Molnar CC: Linux Kernel Mailing List Subject: [PATCH] xen: fix allocation and use of large ldts X-Enigmail-Version: 0.95.6 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When the ldt gets to more than 1 page in size, the kernel uses vmalloc to allocate it. This means that: - when making the ldt RO, we must update the pages in both the vmalloc mapping and the linear mapping to make sure there are no RW aliases. - we need to use arbitrary_virt_to_machine to compute the machine addr for each update Signed-off-by: Jeremy Fitzhardinge --- arch/x86/xen/enlighten.c | 49 ++++++++++++++++++++++++++++++++++++---------- 1 file changed, 39 insertions(+), 10 deletions(-) =================================================================== --- a/arch/x86/xen/enlighten.c +++ b/arch/x86/xen/enlighten.c @@ -305,24 +305,53 @@ return 0; } +/* If 'v' is a vmalloc mapping, then find the linear mapping of the + page (if any) and also set its protections to match. */ +static void set_aliased_prot(void *v, pgprot_t prot) +{ + int level; + pte_t *ptep; + pte_t pte; + unsigned long pfn; + struct page *page; + + ptep = lookup_address((unsigned long)v, &level); + BUG_ON(ptep == NULL); + + pfn = pte_pfn(*ptep); + page = pfn_to_page(pfn); + + pte = pfn_pte(pfn, prot); + + if (HYPERVISOR_update_va_mapping((unsigned long)v, pte, 0)) + BUG(); + + if (!PageHighMem(page)) { + void *av = __va(PFN_PHYS(pfn)); + + if (av != v) + if (HYPERVISOR_update_va_mapping((unsigned long)av, pte, 0)) + BUG(); + } else + kmap_flush_unused(); +} + static void xen_alloc_ldt(struct desc_struct *ldt, unsigned entries) { - unsigned pages = roundup(entries * LDT_ENTRY_SIZE, PAGE_SIZE); - void *v = ldt; + const unsigned entries_per_page = PAGE_SIZE / LDT_ENTRY_SIZE; int i; - for(i = 0; i < pages; i += PAGE_SIZE) - make_lowmem_page_readonly(v + i); + for(i = 0; i < entries; i += entries_per_page) + set_aliased_prot(ldt + i, PAGE_KERNEL_RO); } static void xen_free_ldt(struct desc_struct *ldt, unsigned entries) { - unsigned pages = roundup(entries * LDT_ENTRY_SIZE, PAGE_SIZE); - void *v = ldt; + const unsigned entries_per_page = PAGE_SIZE / LDT_ENTRY_SIZE; int i; - for(i = 0; i < pages; i += PAGE_SIZE) - make_lowmem_page_readwrite(v + i); + for(i = 0; i < entries; i += entries_per_page) + set_aliased_prot(ldt + i, PAGE_KERNEL); } static void xen_set_ldt(const void *addr, unsigned entries) @@ -426,7 +455,7 @@ const void *ptr) { unsigned long lp = (unsigned long)&dt[entrynum]; - xmaddr_t mach_lp = virt_to_machine(lp); + xmaddr_t mach_lp = arbitrary_virt_to_machine(lp); u64 entry = *(u64 *)ptr; preempt_disable(); @@ -559,7 +588,7 @@ } static void xen_load_sp0(struct tss_struct *tss, - struct thread_struct *thread) + struct thread_struct *thread) { struct multicall_space mcs = xen_mc_entry(0); MULTI_stack_switch(mcs.mc, __KERNEL_DS, thread->sp0);