From 92bdaef7b2c5d3cb8abc902faa1f7670a183dcdc Mon Sep 17 00:00:00 2001 From: Konrad Rzeszutek Wilk Date: Thu, 5 May 2011 13:50:43 -0400 Subject: [PATCH] Revert "xen/mmu: Add workaround "x86-64, mm: Put early page table high"" This reverts commit a38647837a411f7df79623128421eef2118b5884. It does not work with certain AMD machines. last_pfn = 0x100000 max_arch_pfn = 0x400000000 initial memory mapped : 0 - 02c3a000 Base memory trampoline at [ffff88000009b000] 9b000 size 20480 init_memory_mapping: 0000000000000000-0000000100000000 0000000000 - 0100000000 page 4k kernel direct mapping tables up to 100000000 @ ff7fb000-100000000 init_memory_mapping: 0000000100000000-00000001e0800000 0100000000 - 01e0800000 page 4k kernel direct mapping tables up to 1e0800000 @ 1df0f3000-1e0000000 xen: setting RW the range fffdc000 - 100000000 RAMDISK: 0203b000 - 02c3a000 No NUMA configuration found Faking a node at 0000000000000000-00000001e0800000 NUMA: Using 63 for the hash shift. Initmem setup node 0 0000000000000000-00000001e0800000 NODE_DATA [00000001dfffb000 - 00000001dfffffff] BUG: unable to handle kernel NULL pointer dereference at (null) IP: [] setup_node_bootmem+0x18a/0x1ea PGD 0 Oops: 0003 [#1] SMP last sysfs file: CPU 0 Modules linked in: Pid: 0, comm: swapper Not tainted 2.6.39-0-virtual #6~smb1 RIP: e030:[] [] setup_node_bootmem+0x18a/0x1ea RSP: e02b:ffffffff81c01e38 EFLAGS: 00010046 RAX: 0000000000000000 RBX: 00000001e0800000 RCX: 0000000000001040 RDX: 0000000000004100 RSI: 0000000000000000 RDI: ffff8801dfffb000 RBP: ffffffff81c01e58 R08: 0000000000000020 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000bfe400 FS: 0000000000000000(0000) GS:ffffffff81cca000(0000) knlGS:0000000000000000 CS: e033 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 0000000001c03000 CR4: 0000000000000660 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process swapper (pid: 0, threadinfo ffffffff81c00000, task ffffffff81c0b020) Stack: 0000000000000040 0000000000000001 0000000000000000 ffffffffffffffff ffffffff81c01e88 ffffffff81cf6c25 0000000000000000 0000000000000000 ffffffff81cf687f 0000000000000000 ffffffff81c01ea8 ffffffff81cf6e45 Call Trace: [] numa_register_memblks.constprop.3+0x150/0x181 [] ? numa_add_memblk+0x7c/0x7c [] numa_init.part.2+0x1c/0x7c [] ? numa_add_memblk+0x7c/0x7c [] numa_init+0x6c/0x70 [] initmem_init+0x39/0x3b [] setup_arch+0x64e/0x769 [] ? printk+0x51/0x53 [] start_kernel+0xd4/0x3f3 [] x86_64_start_reservations+0x132/0x136 [] xen_start_kernel+0x588/0x58f Code: 41 00 00 48 8b 3c c5 a0 24 cc 81 31 c0 40 f6 c7 01 74 05 aa 66 ba ff 40 40 f6 c7 02 74 05 66 ab 83 ea 02 89 d1 c1 e9 02 f6 c2 02 ab 74 02 66 ab 80 e2 01 74 01 aa 49 63 c4 48 c1 eb 0c 44 89 RIP [] setup_node_bootmem+0x18a/0x1ea RSP CR2: 0000000000000000 ---[ end trace a7919e7f17c0a725 ]--- Kernel panic - not syncing: Attempted to kill the idle task! Pid: 0, comm: swapper Tainted: G D 2.6.39-0-virtual #6~smb1 Reported-by: Stefan Bader Signed-off-by: Konrad Rzeszutek Wilk --- arch/x86/xen/mmu.c | 123 --------------------------------------------- 1 file changed, 123 deletions(-) diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c index 55c965b38c27..cf4ef61e425b 100644 --- a/arch/x86/xen/mmu.c +++ b/arch/x86/xen/mmu.c @@ -1463,119 +1463,6 @@ static int xen_pgd_alloc(struct mm_struct *mm) return ret; } -#ifdef CONFIG_X86_64 -static __initdata u64 __last_pgt_set_rw = 0; -static __initdata u64 __pgt_buf_start = 0; -static __initdata u64 __pgt_buf_end = 0; -static __initdata u64 __pgt_buf_top = 0; -/* - * As a consequence of the commit: - * - * commit 4b239f458c229de044d6905c2b0f9fe16ed9e01e - * Author: Yinghai Lu - * Date: Fri Dec 17 16:58:28 2010 -0800 - * - * x86-64, mm: Put early page table high - * - * at some point init_memory_mapping is going to reach the pagetable pages - * area and map those pages too (mapping them as normal memory that falls - * in the range of addresses passed to init_memory_mapping as argument). - * Some of those pages are already pagetable pages (they are in the range - * pgt_buf_start-pgt_buf_end) therefore they are going to be mapped RO and - * everything is fine. - * Some of these pages are not pagetable pages yet (they fall in the range - * pgt_buf_end-pgt_buf_top; for example the page at pgt_buf_end) so they - * are going to be mapped RW. When these pages become pagetable pages and - * are hooked into the pagetable, xen will find that the guest has already - * a RW mapping of them somewhere and fail the operation. - * The reason Xen requires pagetables to be RO is that the hypervisor needs - * to verify that the pagetables are valid before using them. The validation - * operations are called "pinning". - * - * In order to fix the issue we mark all the pages in the entire range - * pgt_buf_start-pgt_buf_top as RO, however when the pagetable allocation - * is completed only the range pgt_buf_start-pgt_buf_end is reserved by - * init_memory_mapping. Hence the kernel is going to crash as soon as one - * of the pages in the range pgt_buf_end-pgt_buf_top is reused (b/c those - * ranges are RO). - * - * For this reason, 'mark_rw_past_pgt' is introduced which is called _after_ - * the init_memory_mapping has completed (in a perfect world we would - * call this function from init_memory_mapping, but lets ignore that). - * - * Because we are called _after_ init_memory_mapping the pgt_buf_[start, - * end,top] have all changed to new values (b/c init_memory_mapping - * is called and setting up another new page-table). Hence, the first time - * we enter this function, we save away the pgt_buf_start value and update - * the pgt_buf_[end,top]. - * - * When we detect that the "old" pgt_buf_start through pgt_buf_end - * PFNs have been reserved (so memblock_x86_reserve_range has been called), - * we immediately set out to RW the "old" pgt_buf_end through pgt_buf_top. - * - * And then we update those "old" pgt_buf_[end|top] with the new ones - * so that we can redo this on the next pagetable. - */ -static __init void mark_rw_past_pgt(void) { - - if (pgt_buf_end > pgt_buf_start) { - u64 addr, size; - - /* Save it away. */ - if (!__pgt_buf_start) { - __pgt_buf_start = pgt_buf_start; - __pgt_buf_end = pgt_buf_end; - __pgt_buf_top = pgt_buf_top; - return; - } - /* If we get the range that starts at __pgt_buf_end that means - * the range is reserved, and that in 'init_memory_mapping' - * the 'memblock_x86_reserve_range' has been called with the - * outdated __pgt_buf_start, __pgt_buf_end (the "new" - * pgt_buf_[start|end|top] refer now to a new pagetable. - * Note: we are called _after_ the pgt_buf_[..] have been - * updated.*/ - - addr = memblock_x86_find_in_range_size(PFN_PHYS(__pgt_buf_start), - &size, PAGE_SIZE); - - /* Still not reserved, meaning 'memblock_x86_reserve_range' - * hasn't been called yet. Update the _end and _top.*/ - if (addr == PFN_PHYS(__pgt_buf_start)) { - __pgt_buf_end = pgt_buf_end; - __pgt_buf_top = pgt_buf_top; - return; - } - - /* OK, the area is reserved, meaning it is time for us to - * set RW for the old end->top PFNs. */ - - /* ..unless we had already done this. */ - if (__pgt_buf_end == __last_pgt_set_rw) - return; - - addr = PFN_PHYS(__pgt_buf_end); - - /* set as RW the rest */ - printk(KERN_DEBUG "xen: setting RW the range %llx - %llx\n", - PFN_PHYS(__pgt_buf_end), PFN_PHYS(__pgt_buf_top)); - - while (addr < PFN_PHYS(__pgt_buf_top)) { - make_lowmem_page_readwrite(__va(addr)); - addr += PAGE_SIZE; - } - /* And update everything so that we are ready for the next - * pagetable (the one created for regions past 4GB) */ - __last_pgt_set_rw = __pgt_buf_end; - __pgt_buf_start = pgt_buf_start; - __pgt_buf_end = pgt_buf_end; - __pgt_buf_top = pgt_buf_top; - } - return; -} -#else -static __init void mark_rw_past_pgt(void) { } -#endif static void xen_pgd_free(struct mm_struct *mm, pgd_t *pgd) { #ifdef CONFIG_X86_64 @@ -1601,14 +1488,6 @@ static __init pte_t mask_rw_pte(pte_t *ptep, pte_t pte) { unsigned long pfn = pte_pfn(pte); - /* - * A bit of optimization. We do not need to call the workaround - * when xen_set_pte_init is called with a PTE with 0 as PFN. - * That is b/c the pagetable at that point are just being populated - * with empty values and we can save some cycles by not calling - * the 'memblock' code.*/ - if (pfn) - mark_rw_past_pgt(); /* * If the new pfn is within the range of the newly allocated * kernel pagetable, and it isn't being mapped into an @@ -2118,8 +1997,6 @@ __init void xen_ident_map_ISA(void) static __init void xen_post_allocator_init(void) { - mark_rw_past_pgt(); - #ifdef CONFIG_XEN_DEBUG pv_mmu_ops.make_pte = PV_CALLEE_SAVE(xen_make_pte_debug); #endif -- GitLab