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2009-03-02xen: deal with virtually mapped percpu dataJeremy Fitzhardinge
The virtually mapped percpu space causes us two problems: - for hypercalls which take an mfn, we need to do a full pagetable walk to convert the percpu va into an mfn, and - when a hypercall requires a page to be mapped RO via all its aliases, we need to make sure its RO in both the percpu mapping and in the linear mapping This primarily affects the gdt and the vcpu info structure. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Cc: Xen-devel <xen-devel@lists.xensource.com> Cc: Gerd Hoffmann <kraxel@redhat.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Tejun Heo <htejun@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-02-13xen: fix xen_flush_tlb_othersIan Campbell
The commit commit 4595f9620cda8a1e973588e743cf5f8436dd20c6 Author: Rusty Russell <rusty@rustcorp.com.au> Date: Sat Jan 10 21:58:09 2009 -0800 x86: change flush_tlb_others to take a const struct cpumask causes xen_flush_tlb_others to allocate a multicall and then issue it without initializing it in the case where the cpumask is empty, leading to: [ 8.354898] 1 multicall(s) failed: cpu 1 [ 8.354921] Pid: 2213, comm: bootclean Not tainted 2.6.29-rc3-x86_32p-xenU-tip #135 [ 8.354937] Call Trace: [ 8.354955] [<c01036e3>] xen_mc_flush+0x133/0x1b0 [ 8.354971] [<c0105d2a>] ? xen_force_evtchn_callback+0x1a/0x30 [ 8.354988] [<c0105a60>] xen_flush_tlb_others+0xb0/0xd0 [ 8.355003] [<c0126643>] flush_tlb_page+0x53/0xa0 [ 8.355018] [<c0176a80>] do_wp_page+0x2a0/0x7c0 [ 8.355034] [<c0238f0a>] ? notify_remote_via_irq+0x3a/0x70 [ 8.355049] [<c0178950>] handle_mm_fault+0x7b0/0xa50 [ 8.355065] [<c0131a3e>] ? wake_up_new_task+0x8e/0xb0 [ 8.355079] [<c01337b5>] ? do_fork+0xe5/0x320 [ 8.355095] [<c0121919>] do_page_fault+0xe9/0x240 [ 8.355109] [<c0121830>] ? do_page_fault+0x0/0x240 [ 8.355125] [<c032457a>] error_code+0x72/0x78 [ 8.355139] call 1/1: op=2863311530 arg=[aaaaaaaa] result=-38 xen_flush_tlb_others+0x41/0xd0 Since empty cpumasks are rare and undoing an xen_mc_entry() is tricky just issue such requests normally. Signed-off-by: Ian Campbell <ian.campbell@citrix.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-02-04xen: fix 32-bit build resulting from mmu moveJeremy Fitzhardinge
Moving the mmu code from enlighten.c to mmu.c inadvertently broke the 32-bit build. Fix it. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2009-01-30x86/paravirt: use callee-saved convention for pte_val/make_pte/etcJeremy Fitzhardinge
Impact: Optimization In the native case, pte_val, make_pte, etc are all just identity functions, so there's no need to clobber a lot of registers over them. (This changes the 32-bit callee-save calling convention to return both EAX and EDX so functions can return 64-bit values.) Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
2009-01-30xen: move remaining mmu-related stuff into mmu.cJeremy Fitzhardinge
Impact: Cleanup Move remaining mmu-related stuff into mmu.c. A general cleanup, and lay the groundwork for later patches. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
2009-01-19x86-64: Move TLB state from PDA to per-cpu and consolidate with 32-bit.Brian Gerst
Signed-off-by: Brian Gerst <brgerst@gmail.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2009-01-16percpu: add optimized generic percpu accessorsIngo Molnar
It is an optimization and a cleanup, and adds the following new generic percpu methods: percpu_read() percpu_write() percpu_add() percpu_sub() percpu_and() percpu_or() percpu_xor() and implements support for them on x86. (other architectures will fall back to a default implementation) The advantage is that for example to read a local percpu variable, instead of this sequence: return __get_cpu_var(var); ffffffff8102ca2b: 48 8b 14 fd 80 09 74 mov -0x7e8bf680(,%rdi,8),%rdx ffffffff8102ca32: 81 ffffffff8102ca33: 48 c7 c0 d8 59 00 00 mov $0x59d8,%rax ffffffff8102ca3a: 48 8b 04 10 mov (%rax,%rdx,1),%rax We can get a single instruction by using the optimized variants: return percpu_read(var); ffffffff8102ca3f: 65 48 8b 05 91 8f fd mov %gs:0x7efd8f91(%rip),%rax I also cleaned up the x86-specific APIs and made the x86 code use these new generic percpu primitives. tj: * fixed generic percpu_sub() definition as Roel Kluin pointed out * added percpu_and() for completeness's sake * made generic percpu ops atomic against preemption Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Tejun Heo <tj@kernel.org>
2009-01-02Merge branch 'cpus4096-for-linus-2' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'cpus4096-for-linus-2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (66 commits) x86: export vector_used_by_percpu_irq x86: use logical apicid in x2apic_cluster's x2apic_cpu_mask_to_apicid_and() sched: nominate preferred wakeup cpu, fix x86: fix lguest used_vectors breakage, -v2 x86: fix warning in arch/x86/kernel/io_apic.c sched: fix warning in kernel/sched.c sched: move test_sd_parent() to an SMP section of sched.h sched: add SD_BALANCE_NEWIDLE at MC and CPU level for sched_mc>0 sched: activate active load balancing in new idle cpus sched: bias task wakeups to preferred semi-idle packages sched: nominate preferred wakeup cpu sched: favour lower logical cpu number for sched_mc balance sched: framework for sched_mc/smt_power_savings=N sched: convert BALANCE_FOR_xx_POWER to inline functions x86: use possible_cpus=NUM to extend the possible cpus allowed x86: fix cpu_mask_to_apicid_and to include cpu_online_mask x86: update io_apic.c to the new cpumask code x86: Introduce topology_core_cpumask()/topology_thread_cpumask() x86: xen: use smp_call_function_many() x86: use work_on_cpu in x86/kernel/cpu/mcheck/mce_amd_64.c ... Fixed up trivial conflict in kernel/time/tick-sched.c manually
2008-12-16x86: xen: use smp_call_function_many()Mike Travis
Impact: use new API, remove cpumask from stack. Change smp_call_function_mask() callers to smp_call_function_many(). This removes a cpumask from the stack, and falls back should allocating the cpumask var fail (only possible with CONFIG_CPUMASKS_OFFSTACK). Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Mike Travis <travis@sgi.com> Cc: jeremy@xensource.com
2008-12-16xen: whitespace/checkpatch cleanupTej
Impact: cleanup Signed-off-by: Tej <bewith.tej@gmail.com> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-23xen: pin correct PGD on suspendIan Campbell
Impact: fix Xen guest boot failure commit eefb47f6a1e855653d275cb90592a3587ea93a09 ("xen: use spin_lock_nest_lock when pinning a pagetable") changed xen_pgd_walk to walk over mm->pgd rather than taking pgd as an argument. This breaks xen_mm_(un)pin_all() because it makes init_mm.pgd readonly instead of the pgd we are interested in and therefore the pin subsequently fails. (XEN) mm.c:2280:d15 Bad type (saw 00000000e8000001 != exp 0000000060000000) for mfn bc464 (pfn 21ca7) (XEN) mm.c:2665:d15 Error while pinning mfn bc464 [ 14.586913] 1 multicall(s) failed: cpu 0 [ 14.586926] Pid: 14, comm: kstop/0 Not tainted 2.6.28-rc5-x86_32p-xenU-00172-gee2f6cc #200 [ 14.586940] Call Trace: [ 14.586955] [<c030c17a>] ? printk+0x18/0x1e [ 14.586972] [<c0103df3>] xen_mc_flush+0x163/0x1d0 [ 14.586986] [<c0104bc1>] __xen_pgd_pin+0xa1/0x110 [ 14.587000] [<c015a330>] ? stop_cpu+0x0/0xf0 [ 14.587015] [<c0104d7b>] xen_mm_pin_all+0x4b/0x70 [ 14.587029] [<c022bcb9>] xen_suspend+0x39/0xe0 [ 14.587042] [<c015a330>] ? stop_cpu+0x0/0xf0 [ 14.587054] [<c015a3cd>] stop_cpu+0x9d/0xf0 [ 14.587067] [<c01417cd>] run_workqueue+0x8d/0x150 [ 14.587080] [<c030e4b3>] ? _spin_unlock_irqrestore+0x23/0x40 [ 14.587094] [<c014558a>] ? prepare_to_wait+0x3a/0x70 [ 14.587107] [<c0141918>] worker_thread+0x88/0xf0 [ 14.587120] [<c01453c0>] ? autoremove_wake_function+0x0/0x50 [ 14.587133] [<c0141890>] ? worker_thread+0x0/0xf0 [ 14.587146] [<c014509c>] kthread+0x3c/0x70 [ 14.587157] [<c0145060>] ? kthread+0x0/0x70 [ 14.587170] [<c0109d1b>] kernel_thread_helper+0x7/0x10 [ 14.587181] call 1/3: op=14 arg=[c0415000] result=0 [ 14.587192] call 2/3: op=14 arg=[e1ca2000] result=0 [ 14.587204] call 3/3: op=26 arg=[c1808860] result=-22 Signed-off-by: Ian Campbell <ian.campbell@citrix.com> Acked-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-07Merge branch 'x86-fixes-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: x86, xen: fix use of pgd_page now that it really does return a page
2008-11-07xen: make sure stray alias mappings are gone before pinningJeremy Fitzhardinge
Xen requires that all mappings of pagetable pages are read-only, so that they can't be updated illegally. As a result, if a page is being turned into a pagetable page, we need to make sure all its mappings are RO. If the page had been used for ioremap or vmalloc, it may still have left over mappings as a result of not having been lazily unmapped. This change makes sure we explicitly mop them all up before pinning the page. Unlike aliases created by kmap, the there can be vmalloc aliases even for non-high pages, so we must do the flush unconditionally. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Cc: Linux Memory Management List <linux-mm@kvack.org> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-06x86, xen: fix use of pgd_page now that it really does return a pageJeremy Fitzhardinge
Impact: fix 32-bit Xen guest boot crash On 32-bit PAE, pud_page, for no good reason, didn't really return a struct page *. Since Jan Beulich's fix "i386/PAE: fix pud_page()", pud_page does return a struct page *. Because PAE has 3 pagetable levels, the pud level is folded into the pgd level, so pgd_page() is the same as pud_page(), and now returns a struct page *. Update the xen/mmu.c code which uses pgd_page() accordingly. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-10-27xen: fix Xen domU boot with batched mprotectChris Lalancette
Impact: fix guest kernel boot crash on certain configs Recent i686 2.6.27 kernels with a certain amount of memory (between 736 and 855MB) have a problem booting under a hypervisor that supports batched mprotect (this includes the RHEL-5 Xen hypervisor as well as any 3.3 or later Xen hypervisor). The problem ends up being that xen_ptep_modify_prot_commit() is using virt_to_machine to calculate which pfn to update. However, this only works for pages that are in the p2m list, and the pages coming from change_pte_range() in mm/mprotect.c are kmap_atomic pages. Because of this, we can run into the situation where the lookup in the p2m table returns an INVALID_MFN, which we then try to pass to the hypervisor, which then (correctly) denies the request to a totally bogus pfn. The right thing to do is to use arbitrary_virt_to_machine, so that we can be sure we are modifying the right pfn. This unfortunately introduces a performance penalty because of a full page-table-walk, but we can avoid that penalty for pages in the p2m list by checking if virt_addr_valid is true, and if so, just doing the lookup in the p2m table. The attached patch implements this, and allows my 2.6.27 i686 based guest with 768MB of memory to boot on a RHEL-5 hypervisor again. Thanks to Jeremy for the suggestions about how to fix this particular issue. Signed-off-by: Chris Lalancette <clalance@redhat.com> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Cc: Chris Lalancette <clalance@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-10-20mm: rewrite vmap layerNick Piggin
Rewrite the vmap allocator to use rbtrees and lazy tlb flushing, and provide a fast, scalable percpu frontend for small vmaps (requires a slightly different API, though). The biggest problem with vmap is actually vunmap. Presently this requires a global kernel TLB flush, which on most architectures is a broadcast IPI to all CPUs to flush the cache. This is all done under a global lock. As the number of CPUs increases, so will the number of vunmaps a scaled workload will want to perform, and so will the cost of a global TLB flush. This gives terrible quadratic scalability characteristics. Another problem is that the entire vmap subsystem works under a single lock. It is a rwlock, but it is actually taken for write in all the fast paths, and the read locking would likely never be run concurrently anyway, so it's just pointless. This is a rewrite of vmap subsystem to solve those problems. The existing vmalloc API is implemented on top of the rewritten subsystem. The TLB flushing problem is solved by using lazy TLB unmapping. vmap addresses do not have to be flushed immediately when they are vunmapped, because the kernel will not reuse them again (would be a use-after-free) until they are reallocated. So the addresses aren't allocated again until a subsequent TLB flush. A single TLB flush then can flush multiple vunmaps from each CPU. XEN and PAT and such do not like deferred TLB flushing because they can't always handle multiple aliasing virtual addresses to a physical address. They now call vm_unmap_aliases() in order to flush any deferred mappings. That call is very expensive (well, actually not a lot more expensive than a single vunmap under the old scheme), however it should be OK if not called too often. The virtual memory extent information is stored in an rbtree rather than a linked list to improve the algorithmic scalability. There is a per-CPU allocator for small vmaps, which amortizes or avoids global locking. To use the per-CPU interface, the vm_map_ram / vm_unmap_ram interfaces must be used in place of vmap and vunmap. Vmalloc does not use these interfaces at the moment, so it will not be quite so scalable (although it will use lazy TLB flushing). As a quick test of performance, I ran a test that loops in the kernel, linearly mapping then touching then unmapping 4 pages. Different numbers of tests were run in parallel on an 4 core, 2 socket opteron. Results are in nanoseconds per map+touch+unmap. threads vanilla vmap rewrite 1 14700 2900 2 33600 3000 4 49500 2800 8 70631 2900 So with a 8 cores, the rewritten version is already 25x faster. In a slightly more realistic test (although with an older and less scalable version of the patch), I ripped the not-very-good vunmap batching code out of XFS, and implemented the large buffer mapping with vm_map_ram and vm_unmap_ram... along with a couple of other tricks, I was able to speed up a large directory workload by 20x on a 64 CPU system. I believe vmap/vunmap is actually sped up a lot more than 20x on such a system, but I'm running into other locks now. vmap is pretty well blown off the profiles. Before: 1352059 total 0.1401 798784 _write_lock 8320.6667 <- vmlist_lock 529313 default_idle 1181.5022 15242 smp_call_function 15.8771 <- vmap tlb flushing 2472 __get_vm_area_node 1.9312 <- vmap 1762 remove_vm_area 4.5885 <- vunmap 316 map_vm_area 0.2297 <- vmap 312 kfree 0.1950 300 _spin_lock 3.1250 252 sn_send_IPI_phys 0.4375 <- tlb flushing 238 vmap 0.8264 <- vmap 216 find_lock_page 0.5192 196 find_next_bit 0.3603 136 sn2_send_IPI 0.2024 130 pio_phys_write_mmr 2.0312 118 unmap_kernel_range 0.1229 After: 78406 total 0.0081 40053 default_idle 89.4040 33576 ia64_spinlock_contention 349.7500 1650 _spin_lock 17.1875 319 __reg_op 0.5538 281 _atomic_dec_and_lock 1.0977 153 mutex_unlock 1.5938 123 iget_locked 0.1671 117 xfs_dir_lookup 0.1662 117 dput 0.1406 114 xfs_iget_core 0.0268 92 xfs_da_hashname 0.1917 75 d_alloc 0.0670 68 vmap_page_range 0.0462 <- vmap 58 kmem_cache_alloc 0.0604 57 memset 0.0540 52 rb_next 0.1625 50 __copy_user 0.0208 49 bitmap_find_free_region 0.2188 <- vmap 46 ia64_sn_udelay 0.1106 45 find_inode_fast 0.1406 42 memcmp 0.2188 42 finish_task_switch 0.1094 42 __d_lookup 0.0410 40 radix_tree_lookup_slot 0.1250 37 _spin_unlock_irqrestore 0.3854 36 xfs_bmapi 0.0050 36 kmem_cache_free 0.0256 35 xfs_vn_getattr 0.0322 34 radix_tree_lookup 0.1062 33 __link_path_walk 0.0035 31 xfs_da_do_buf 0.0091 30 _xfs_buf_find 0.0204 28 find_get_page 0.0875 27 xfs_iread 0.0241 27 __strncpy_from_user 0.2812 26 _xfs_buf_initialize 0.0406 24 _xfs_buf_lookup_pages 0.0179 24 vunmap_page_range 0.0250 <- vunmap 23 find_lock_page 0.0799 22 vm_map_ram 0.0087 <- vmap 20 kfree 0.0125 19 put_page 0.0330 18 __kmalloc 0.0176 17 xfs_da_node_lookup_int 0.0086 17 _read_lock 0.0885 17 page_waitqueue 0.0664 vmap has gone from being the top 5 on the profiles and flushing the crap out of all TLBs, to using less than 1% of kernel time. [akpm@linux-foundation.org: cleanups, section fix] [akpm@linux-foundation.org: fix build on alpha] Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Cc: Krzysztof Helt <krzysztof.h1@poczta.fm> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-09xen: use spin_lock_nest_lock when pinning a pagetableJeremy Fitzhardinge
When pinning/unpinning a pagetable with split pte locks, we can end up holding multiple pte locks at once (we need to hold the locks while there's a pending batched hypercall affecting the pte page). Because all the pte locks are in the same lock class, lockdep thinks that we're potentially taking a lock recursively. This warning is spurious because we always take the pte locks while holding mm->page_table_lock. lockdep now has spin_lock_nest_lock to express this kind of dominant lock use, so use it here so that lockdep knows what's going on. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-09-10Merge branch 'core/xen' into x86/xenIngo Molnar
2008-09-10mm: define USE_SPLIT_PTLOCKS rather than repeating expressionJeremy Fitzhardinge
Define USE_SPLIT_PTLOCKS as a constant expression rather than repeating "NR_CPUS >= CONFIG_SPLIT_PTLOCK_CPUS" all over the place. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Acked-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-08-21xen: add debugfs supportJeremy Fitzhardinge
Add support for exporting statistics on mmu updates, multicall batching and pv spinlocks into debugfs. The base path is xen/ and each subsystem adds its own directory: mmu, multicalls, spinlocks. In each directory, writing 1 to "zero_stats" will cause the corresponding stats to be zeroed the next time they're updated. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Acked-by: Jan Beulich <jbeulich@novell.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-08-20xen: add xen_ prefixes to make tracing with ftrace easierJeremy Fitzhardinge
It's easier to pattern match on Xen function if they all start with xen_. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-08-20xen: clarify locking used when pinning a pagetable.Jeremy Fitzhardinge
Add some comments explaining the locking and pinning algorithm when using split pte locks. Also implement a minor optimisation of not pinning the PTE when not using split pte locks. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Cc: Xen-devel <xen-devel@lists.xensource.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-22x86: add PTE_FLAGS_MASKJeremy Fitzhardinge
PTE_PFN_MASK was getting lonely, so I made it a friend. Signed-off-by: Jeremy Fitzhardinge <jeremy@goop.org> Cc: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-22x86: rename PTE_MASK to PTE_PFN_MASKJeremy Fitzhardinge
Rusty, in his peevish way, complained that macros defining constants should have a name which somewhat accurately reflects the actual purpose of the constant. Aside from the fact that PTE_MASK gives no clue as to what's actually being masked, and is misleadingly similar to the functionally entirely different PMD_MASK, PUD_MASK and PGD_MASK, I don't really see what the problem is. But if this patch silences the incessent noise, then it will have achieved its goal (TODO: write test-case). Signed-off-by: Jeremy Fitzhardinge <jeremy@goop.org> Cc: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-16xen64: allocate and manage user pagetablesJeremy Fitzhardinge
Because the x86_64 architecture does not enforce segment limits, Xen cannot protect itself with them as it does in 32-bit mode. Therefore, to protect itself, it runs the guest kernel in ring 3. Since it also runs the guest userspace in ring3, the guest kernel must maintain a second pagetable for its userspace, which does not map kernel space. Naturally, the guest kernel pagetables map both kernel and userspace. The userspace pagetable is attached to the corresponding kernel pagetable via the pgd's page->private field. It is allocated and freed at the same time as the kernel pgd via the paravirt_pgd_alloc/free hooks. Fortunately, the user pagetable is almost entirely shared with the kernel pagetable; the only difference is the pgd page itself. set_pgd will populate all entries in the kernel pagetable, and also set the corresponding user pgd entry if the address is less than STACK_TOP_MAX. The user pagetable must be pinned and unpinned with the kernel one, but because the pagetables are aliased, pgd_walk() only needs to be called on the kernel pagetable. The user pgd page is then pinned/unpinned along with the kernel pgd page. xen_write_cr3 must write both the kernel and user cr3s. The init_mm.pgd pagetable never has a user pagetable allocated for it, because it can never be used while running usermode. One awkward area is that early in boot the page structures are not available. No user pagetable can exist at that point, but it complicates the logic to avoid looking at the page structure. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Cc: Stephen Tweedie <sct@redhat.com> Cc: Eduardo Habkost <ehabkost@redhat.com> Cc: Mark McLoughlin <markmc@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-16xen: rework pgd_walk to deal with 32/64 bitJeremy Fitzhardinge
Rewrite pgd_walk to deal with 64-bit address spaces. There are two notible features of 64-bit workspaces: 1. The physical address is only 48 bits wide, with the upper 16 bits being sign extension; kernel addresses are negative, and userspace is positive. 2. The Xen hypervisor mapping is at the negative-most address, just above the sign-extension hole. 1. means that we can't easily use addresses when traversing the space, since we must deal with sign extension. This rewrite expresses everything in terms of pgd/pud/pmd indices, which means we don't need to worry about the exact configuration of the virtual memory space. This approach works equally well in 32-bit. To deal with 2, assume the hole is between the uppermost userspace address and PAGE_OFFSET. For 64-bit this skips the Xen mapping hole. For 32-bit, the hole is zero-sized. In all cases, the uppermost kernel address is FIXADDR_TOP. A side-effect of this patch is that the upper boundary is actually handled properly, exposing a long-standing bug in 32-bit, which failed to pin kernel pmd page. The kernel pmd is not shared, and so must be explicitly pinned, even though the kernel ptes are shared and don't need pinning. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Cc: Stephen Tweedie <sct@redhat.com> Cc: Eduardo Habkost <ehabkost@redhat.com> Cc: Mark McLoughlin <markmc@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-16xen: use set_pte_vaddrJeremy Fitzhardinge
Make Xen's set_pte_mfn() use set_pte_vaddr rather than copying it. Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com> Signed-off-by: Juan Quintela <quintela@redhat.com> Signed-off-by: Mark McLoughlin <markmc@redhat.com> Cc: Stephen Tweedie <sct@redhat.com> Cc: Eduardo Habkost <ehabkost@redhat.com> Cc: Mark McLoughlin <markmc@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-16xen64: use arbitrary_virt_to_machine for xen_set_pmdJeremy Fitzhardinge
When building initial pagetables in 64-bit kernel the pud/pmd pointer may be in ioremap/fixmap space, so we need to walk the pagetable to look up the physical address. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Cc: Stephen Tweedie <sct@redhat.com> Cc: Eduardo Habkost <ehabkost@redhat.com> Cc: Mark McLoughlin <markmc@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-16xen: fix truncation of machine addressJeremy Fitzhardinge
arbitrary_virt_to_machine can truncate a machine address if its above 4G. Cast the problem away. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Cc: Stephen Tweedie <sct@redhat.com> Cc: Eduardo Habkost <ehabkost@redhat.com> Cc: Mark McLoughlin <markmc@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-16xen64: get active_mm from the pdaJeremy Fitzhardinge
x86_64 stores the active_mm in the pda, so fetch it from there. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Cc: Stephen Tweedie <sct@redhat.com> Cc: Eduardo Habkost <ehabkost@redhat.com> Cc: Mark McLoughlin <markmc@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-16xen64: add extra pv_mmu_opsJeremy Fitzhardinge
We need extra pv_mmu_ops for 64-bit, to deal with the extra level of pagetable. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Cc: Stephen Tweedie <sct@redhat.com> Cc: Eduardo Habkost <ehabkost@redhat.com> Cc: Mark McLoughlin <markmc@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-16x86: use __page_aligned_data/bssJeremy Fitzhardinge
Update arch/x86's use of page-aligned variables. The change to arch/x86/xen/mmu.c fixes an actual bug, but the rest are cleanups and to set a precedent. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Cc: Stephen Tweedie <sct@redhat.com> Cc: Eduardo Habkost <ehabkost@redhat.com> Cc: Mark McLoughlin <markmc@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-16pvops-64: call paravirt_post_allocator_init() on setup_arch()Eduardo Habkost
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Cc: Stephen Tweedie <sct@redhat.com> Cc: Mark McLoughlin <markmc@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-15Merge branch 'generic-ipi' into generic-ipi-for-linusIngo Molnar
Conflicts: arch/powerpc/Kconfig arch/s390/kernel/time.c arch/x86/kernel/apic_32.c arch/x86/kernel/cpu/perfctr-watchdog.c arch/x86/kernel/i8259_64.c arch/x86/kernel/ldt.c arch/x86/kernel/nmi_64.c arch/x86/kernel/smpboot.c arch/x86/xen/smp.c include/asm-x86/hw_irq_32.h include/asm-x86/hw_irq_64.h include/asm-x86/mach-default/irq_vectors.h include/asm-x86/mach-voyager/irq_vectors.h include/asm-x86/smp.h kernel/Makefile Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-08Merge branches 'x86/numa-fixes', 'x86/apic', 'x86/apm', 'x86/bitops', ↵Ingo Molnar
'x86/build', 'x86/cleanups', 'x86/cpa', 'x86/cpu', 'x86/defconfig', 'x86/gart', 'x86/i8259', 'x86/intel', 'x86/irqstats', 'x86/kconfig', 'x86/ldt', 'x86/mce', 'x86/memtest', 'x86/pat', 'x86/ptemask', 'x86/resumetrace', 'x86/threadinfo', 'x86/timers', 'x86/vdso' and 'x86/xen' into x86/devel
2008-07-04xen: fix address truncation in pte mfn<->pfn conversionJeremy Fitzhardinge
When converting the page number in a pte/pmd/pud/pgd between machine and pseudo-physical addresses, the converted result was being truncated at 32-bits. This caused failures on machines with more than 4G of physical memory. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Cc: "Christopher S. Aker" <caker@theshore.net> Cc: Ian Campbell <Ian.Campbell@eu.citrix.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-26x86: convert to generic helpers for IPI function callsJens Axboe
This converts x86, x86-64, and xen to use the new helpers for smp_call_function() and friends, and adds support for smp_call_function_single(). Acked-by: Ingo Molnar <mingo@elte.hu> Acked-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-06-25xen: add mechanism to extend existing multicallsJeremy Fitzhardinge
Some Xen hypercalls accept an array of operations to work on. In general this is because its more efficient for the hypercall to the work all at once rather than as separate hypercalls (even batched as a multicall). This patch adds a mechanism (xen_mc_extend_args()) to allocate more argument space to the last-issued multicall, in order to extend its argument list. The user of this mechanism is xen/mmu.c, which uses it to extend the args array of mmu_update. This is particularly valuable when doing the update for a large mprotect, which goes via ptep_modify_prot_commit(), but it also manages to batch updates to pgd/pmds as well. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Acked-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-25xen: implement ptep_modify_prot_start/commitJeremy Fitzhardinge
Xen has a pte update function which will update a pte while preserving its accessed and dirty bits. This means that ptep_modify_prot_start() can be implemented as a simple read of the pte value. The hardware may update the pte in the meantime, but ptep_modify_prot_commit() updates it while preserving any changes that may have happened in the meantime. The updates in ptep_modify_prot_commit() are batched if we're currently in lazy mmu mode. The mmu_update hypercall can take a batch of updates to perform, but this code doesn't make particular use of that feature, in favour of using generic multicall batching to get them all into the hypervisor. The net effect of this is that each mprotect pte update turns from two expensive trap-and-emulate faults into they hypervisor into a single hypercall whose cost is amortized in a batched multicall. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Acked-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-24xen: remove support for non-PAE 32-bitJeremy Fitzhardinge
Non-PAE operation has been deprecated in Xen for a while, and is rarely tested or used. xen-unstable has now officially dropped non-PAE support. Since Xen/pvops' non-PAE support has also been broken for a while, we may as well completely drop it altogether. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-20xen: don't drop NX bitJeremy Fitzhardinge
Because NX is now enforced properly, we must put the hypercall page into the .text segment so that it is executable. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Cc: Stable Kernel <stable@kernel.org> Cc: the arch/x86 maintainers <x86@kernel.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-20xen: mask unwanted pte bits in __supported_pte_maskJeremy Fitzhardinge
[ Stable: this isn't a bugfix in itself, but it's a pre-requiste for "xen: don't drop NX bit" ] Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Cc: Stable Kernel <stable@kernel.org> Cc: the arch/x86 maintainers <x86@kernel.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-20xen: don't drop NX bitJeremy Fitzhardinge
Because NX is now enforced properly, we must put the hypercall page into the .text segment so that it is executable. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Cc: Stable Kernel <stable@kernel.org> Cc: the arch/x86 maintainers <x86@kernel.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-20xen: mask unwanted pte bits in __supported_pte_maskJeremy Fitzhardinge
[ Stable: this isn't a bugfix in itself, but it's a pre-requiste for "xen: don't drop NX bit" ] Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Cc: Stable Kernel <stable@kernel.org> Cc: the arch/x86 maintainers <x86@kernel.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-16Merge branch 'linus' into x86/xenIngo Molnar
2008-06-02xen: avoid hypercalls when updating unpinned pud/pmdJeremy Fitzhardinge
When operating on an unpinned pagetable (ie, one under construction or destruction), it isn't necessary to use a hypercall to update a pud/pmd entry. Jan Beulich observed that a similar optimisation avoided many thousands of hypercalls while doing a kernel build. One tricky part is that early in the kernel boot there's no page structure, so we can't check to see if the page is pinned. In that case, we just always use the hypercall. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Cc: Jan Beulich <jbeulich@novell.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-02xen: export get_phys_to_machineIngo Molnar
-tip testing found the following xen-console symbols trouble: ERROR: "get_phys_to_machine" [drivers/video/xen-fbfront.ko] undefined! ERROR: "get_phys_to_machine" [drivers/net/xen-netfront.ko] undefined! ERROR: "get_phys_to_machine" [drivers/input/xen-kbdfront.ko] undefined! with: http://redhat.com/~mingo/misc/config-Mon_Jun__2_12_25_13_CEST_2008.bad
2008-05-28xen: fix early bootup crash on native hardwareIngo Molnar
-tip tree auto-testing found the following early bootup hang: --------------> get_memcfg_from_srat: assigning address to rsdp RSD PTR v0 [Nvidia] BUG: Int 14: CR2 ffd00040 EDI 8092fbfe ESI ffd00040 EBP 80b0aee8 ESP 80b0aed0 EBX 000f76f0 EDX 0000000e ECX 00000003 EAX ffd00040 err 00000000 EIP 802c055a CS 00000060 flg 00010006 Stack: ffd00040 80bc78d0 80b0af6c 80b1dbfe 8093d8ba 00000008 80b42810 80b4ddb4 80b42842 00000000 80b0af1c 801079c8 808e724e 00000000 80b42871 802c0531 00000100 00000000 0003fff0 80b0af40 80129999 00040100 00040100 00000000 Pid: 0, comm: swapper Not tainted 2.6.26-rc4-sched-devel.git #570 [<802c055a>] ? strncmp+0x11/0x25 [<80b1dbfe>] ? get_memcfg_from_srat+0xb4/0x568 [<801079c8>] ? mcount_call+0x5/0x9 [<802c0531>] ? strcmp+0xa/0x22 [<80129999>] ? printk+0x38/0x3a [<80129999>] ? printk+0x38/0x3a [<8011b122>] ? memory_present+0x66/0x6f [<80b216b4>] ? setup_memory+0x13/0x40c [<80b16b47>] ? propagate_e820_map+0x80/0x97 [<80b1622a>] ? setup_arch+0x248/0x477 [<80129999>] ? printk+0x38/0x3a [<80b11759>] ? start_kernel+0x6e/0x2eb [<80b110fc>] ? i386_start_kernel+0xeb/0xf2 ======================= <------ with this config: http://redhat.com/~mingo/misc/config-Wed_May_28_01_33_33_CEST_2008.bad The thing is, the crash makes little sense at first sight. We crash on a benign-looking printk. The code around it got changed in -tip but checking those topic branches individually did not reproduce the bug. Bisection led to this commit: | d5edbc1f75420935b1ec7e65df10c8f81cea82de is first bad commit | commit d5edbc1f75420935b1ec7e65df10c8f81cea82de | Author: Jeremy Fitzhardinge <jeremy@goop.org> | Date: Mon May 26 23:31:22 2008 +0100 | | xen: add p2m mfn_list_list Which is somewhat surprising, as on native hardware Xen client side should have little to no side-effects. After some head scratching, it turns out the following happened: randconfig enabled the following Xen options: CONFIG_XEN=y CONFIG_XEN_MAX_DOMAIN_MEMORY=8 # CONFIG_XEN_BLKDEV_FRONTEND is not set # CONFIG_XEN_NETDEV_FRONTEND is not set CONFIG_HVC_XEN=y # CONFIG_XEN_BALLOON is not set which activated this piece of code in arch/x86/xen/mmu.c: > @@ -69,6 +69,13 @@ > __attribute__((section(".data.page_aligned"))) = > { [ 0 ... TOP_ENTRIES - 1] = &p2m_missing[0] }; > > +/* Arrays of p2m arrays expressed in mfns used for save/restore */ > +static unsigned long p2m_top_mfn[TOP_ENTRIES] > + __attribute__((section(".bss.page_aligned"))); > + > +static unsigned long p2m_top_mfn_list[TOP_ENTRIES / P2M_ENTRIES_PER_PAGE] > + __attribute__((section(".bss.page_aligned"))); The problem is, you must only put variables into .bss.page_aligned that have a _size_ that is _exactly_ page aligned. In this case the size of p2m_top_mfn_list is not page aligned: 80b8d000 b p2m_top_mfn 80b8f000 b p2m_top_mfn_list 80b8f008 b softirq_stack 80b97008 b hardirq_stack 80b9f008 b bm_pte So all subsequent variables get unaligned which, depending on luck, breaks the kernel in various funny ways. In this case what killed the kernel first was the misaligned bootmap pte page, resulting in that creative crash above. Anyway, this was a fun bug to track down :-) I think the moral is that .bss.page_aligned is a dangerous construct in its current form, and the symptoms of breakage are very non-trivial, so i think we need build-time checks to make sure all symbols in .bss.page_aligned are truly page aligned. The Xen fix below gets the kernel booting again. Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-05-27xen: implement save/restoreJeremy Fitzhardinge
This patch implements Xen save/restore and migration. Saving is triggered via xenbus, which is polled in drivers/xen/manage.c. When a suspend request comes in, the kernel prepares itself for saving by: 1 - Freeze all processes. This is primarily to prevent any partially-completed pagetable updates from confusing the suspend process. If CONFIG_PREEMPT isn't defined, then this isn't necessary. 2 - Suspend xenbus and other devices 3 - Stop_machine, to make sure all the other vcpus are quiescent. The Xen tools require the domain to run its save off vcpu0. 4 - Within the stop_machine state, it pins any unpinned pgds (under construction or destruction), performs canonicalizes various other pieces of state (mostly converting mfns to pfns), and finally 5 - Suspend the domain Restore reverses the steps used to save the domain, ending when all the frozen processes are thawed. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-27xen: add p2m mfn_list_listJeremy Fitzhardinge
When saving a domain, the Xen tools need to remap all our mfns to portable pfns. In order to remap our p2m table, it needs to know where all its pages are, so maintain the references to the p2m table for it to use. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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