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* Merge branch 'x86-xen-for-linus' of ↵Linus Torvalds2009-09-144-29/+133
|\ | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'x86-xen-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: x86: split __phys_addr out into separate file xen: use stronger barrier after unlocking lock xen: only enable interrupts while actually blocking for spinlock xen: make -fstack-protector work under Xen
| * xen: use stronger barrier after unlocking lockYang Xiaowei2009-09-101-2/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We need to have a stronger barrier between releasing the lock and checking for any waiting spinners. A compiler barrier is not sufficient because the CPU's ordering rules do not prevent the read xl->spinners from happening before the unlock assignment, as they are different memory locations. We need to have an explicit barrier to enforce the write-read ordering to different memory locations. Because of it, I can't bring up > 4 HVM guests on one SMP machine. [ Code and commit comments expanded -J ] [ Impact: avoid deadlock when using Xen PV spinlocks ] Signed-off-by: Yang Xiaowei <xiaowei.yang@intel.com> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
| * xen: only enable interrupts while actually blocking for spinlockJeremy Fitzhardinge2009-09-101-8/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Where possible we enable interrupts while waiting for a spinlock to become free, in order to reduce big latency spikes in interrupt handling. However, at present if we manage to pick up the spinlock just before blocking, we'll end up holding the lock with interrupts enabled for a while. This will cause a deadlock if we recieve an interrupt in that window, and the interrupt handler tries to take the lock too. Solve this by shrinking the interrupt-enabled region to just around the blocking call. [ Impact: avoid race/deadlock when using Xen PV spinlocks ] Reported-by: "Yang, Xiaowei" <xiaowei.yang@intel.com> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
| * xen: make -fstack-protector work under XenJeremy Fitzhardinge2009-09-103-19/+115
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | -fstack-protector uses a special per-cpu "stack canary" value. gcc generates special code in each function to test the canary to make sure that the function's stack hasn't been overrun. On x86-64, this is simply an offset of %gs, which is the usual per-cpu base segment register, so setting it up simply requires loading %gs's base as normal. On i386, the stack protector segment is %gs (rather than the usual kernel percpu %fs segment register). This requires setting up the full kernel GDT and then loading %gs accordingly. We also need to make sure %gs is initialized when bringing up secondary cpus too. To keep things consistent, we do the full GDT/segment register setup on both architectures. Because we need to avoid -fstack-protected code before setting up the GDT and because there's no way to disable it on a per-function basis, several files need to have stack-protector inhibited. [ Impact: allow Xen booting with stack-protector enabled ] Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
* | Merge branch 'x86-cpu-for-linus' of ↵Linus Torvalds2009-09-141-1/+1
|\ \ | |/ |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'x86-cpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (22 commits) x86: Fix code patching for paravirt-alternatives on 486 x86, msr: change msr-reg.o to obj-y, and export its symbols x86: Use hard_smp_processor_id() to get apic id for AMD K8 cpus x86, sched: Workaround broken sched domain creation for AMD Magny-Cours x86, mcheck: Use correct cpumask for shared bank4 x86, cacheinfo: Fixup L3 cache information for AMD multi-node processors x86: Fix CPU llc_shared_map information for AMD Magny-Cours x86, msr: Fix msr-reg.S compilation with gas 2.16.1, on 32-bit too x86: Move kernel_fpu_using to irq_fpu_usable in asm/i387.h x86, msr: fix msr-reg.S compilation with gas 2.16.1 x86, msr: Export the register-setting MSR functions via /dev/*/msr x86, msr: Create _on_cpu helpers for {rw,wr}msr_safe_regs() x86, msr: Have the _safe MSR functions return -EIO, not -EFAULT x86, msr: CFI annotations, cleanups for msr-reg.S x86, asm: Make _ASM_EXTABLE() usable from assembly code x86, asm: Add 32-bit versions of the combined CFI macros x86, AMD: Disable wrongly set X86_FEATURE_LAHF_LM CPUID bit x86, msr: Rewrite AMD rd/wrmsr variants x86, msr: Add rd/wrmsr interfaces with preset registers x86: add specific support for Intel Atom architecture ...
| * x86, msr: Have the _safe MSR functions return -EIO, not -EFAULTH. Peter Anvin2009-09-011-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | For some reason, the _safe MSR functions returned -EFAULT, not -EIO. However, the only user which cares about the return code as anything other than a boolean is the MSR driver, which wants -EIO. Change it to -EIO across the board. Signed-off-by: H. Peter Anvin <hpa@zytor.com> Cc: Jeremy Fitzhardinge <jeremy@xensource.com> Cc: Chris Wright <chrisw@sous-sol.org> Cc: Alok Kataria <akataria@vmware.com> Cc: Rusty Russell <rusty@rustcorp.com.au>
* | x86, xen: Initialize cx to suppress warningH. Peter Anvin2009-08-261-0/+1
| | | | | | | | | | | | | | | | Initialize cx before calling xen_cpuid(), in order to suppress the "may be used uninitialized in this function" warning. Signed-off-by: H. Peter Anvin <hpa@zytor.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org>
* | x86, xen: Suppress WP test on XenJeremy Fitzhardinge2009-08-261-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | Xen always runs on CPUs which properly support WP enforcement in privileged mode, so there's no need to test for it. This also works around a crash reported by Arnd Hannemann, though I think its just a band-aid for that case. Reported-by: Arnd Hannemann <hannemann@nets.rwth-aachen.de> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Acked-by: Pekka Enberg <penberg@cs.helsinki.fi> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
* | Merge branch 'bugfix' of ↵Ingo Molnar2009-08-202-12/+14
|\ \ | |/ |/| | | git://git.kernel.org/pub/scm/linux/kernel/git/jeremy/xen into x86/urgent
| * xen: rearrange things to fix stackprotectorJeremy Fitzhardinge2009-08-202-12/+14
| | | | | | | | | | | | | | | | | | Make sure the stack-protector segment registers are properly set up before calling any functions which may have stack-protection compiled into them. [ Impact: prevent Xen early-boot crash when stack-protector is enabled ] Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
* | Merge branch 'x86-xen-for-linus' of ↵Linus Torvalds2009-06-114-24/+71
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'x86-xen-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (42 commits) xen: cache cr0 value to avoid trap'n'emulate for read_cr0 xen/x86-64: clean up warnings about IST-using traps xen/x86-64: fix breakpoints and hardware watchpoints xen: reserve Xen start_info rather than e820 reserving xen: add FIX_TEXT_POKE to fixmap lguest: update lazy mmu changes to match lguest's use of kvm hypercalls xen: honour VCPU availability on boot xen: add "capabilities" file xen: drop kexec bits from /sys/hypervisor since kexec isn't implemented yet xen/sys/hypervisor: change writable_pt to features xen: add /sys/hypervisor support xen/xenbus: export xenbus_dev_changed xen: use device model for suspending xenbus devices xen: remove suspend_cancel hook xen/dev-evtchn: clean up locking in evtchn xen: export ioctl headers to userspace xen: add /dev/xen/evtchn driver xen: add irq_from_evtchn xen: clean up gate trap/interrupt constants xen: set _PAGE_NX in __supported_pte_mask before pagetable construction ...
| * | xen: cache cr0 value to avoid trap'n'emulate for read_cr0Jeremy Fitzhardinge2009-05-091-1/+17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | stts() is implemented in terms of read_cr0/write_cr0 to update the state of the TS bit. This happens during context switch, and so is fairly performance critical. Rather than falling back to a trap-and-emulate native read_cr0, implement our own by caching the last-written value from write_cr0 (the TS bit is the only one we really care about). Impact: optimise Xen context switches Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
| * | xen/x86-64: clean up warnings about IST-using trapsJeremy Fitzhardinge2009-05-091-2/+20
| | | | | | | | | | | | | | | | | | | | | | | | | | | Ignore known IST-using traps. Aside from the debugger traps, they're low-level faults which Xen will handle for us, so the kernel needn't worry about them. Keep warning in case unknown trap starts using IST. Impact: suppress spurious warnings Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
| * | xen/x86-64: fix breakpoints and hardware watchpointsJeremy Fitzhardinge2009-05-091-1/+18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Native x86-64 uses the IST mechanism to run int3 and debug traps on an alternative stack. Xen does not do this, and so the frames were being misinterpreted by the ptrace code. This change special-cases these two exceptions by using Xen variants which run on the normal kernel stack properly. Impact: avoid crash or bad data when IST trap is invoked under Xen Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
| * | xen: reserve Xen start_info rather than e820 reservingJeremy Fitzhardinge2009-05-081-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Use reserve_early rather than e820 reservations for Xen start info and mfn->pfn table, so that the memory use is a bit more self-documenting. [ Impact: cleanup ] Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Cc: Xen-devel <xen-devel@lists.xensource.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> LKML-Reference: <4A032EF1.6070708@goop.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * | Merge branch 'x86/urgent' into x86/xenIngo Molnar2009-05-082-2/+12
| |\| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Conflicts: arch/frv/include/asm/pgtable.h arch/x86/include/asm/required-features.h arch/x86/xen/mmu.c Merge reason: x86/xen was on a .29 base still, move it to a fresher branch and pick up Xen fixes as well, plus resolve conflicts Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * | xen: add FIX_TEXT_POKE to fixmapJeremy Fitzhardinge2009-04-101-0/+3
| | | | | | | | | | | | | | | | | | | | | FIX_TEXT_POKE[01] are used to map kernel addresses, so they're mapping pfns, not mfns. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
| * | Merge commit 'origin/master' into for-linus/xen/masterJeremy Fitzhardinge2009-04-072-7/+6Star
| |\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | * commit 'origin/master': (4825 commits) Fix build errors due to CONFIG_BRANCH_TRACER=y parport: Use the PCI IRQ if offered tty: jsm cleanups Adjust path to gpio headers KGDB_SERIAL_CONSOLE check for module Change KCONFIG name tty: Blackin CTS/RTS Change hardware flow control from poll to interrupt driven Add support for the MAX3100 SPI UART. lanana: assign a device name and numbering for MAX3100 serqt: initial clean up pass for tty side tty: Use the generic RS485 ioctl on CRIS tty: Correct inline types for tty_driver_kref_get() splice: fix deadlock in splicing to file nilfs2: support nanosecond timestamp nilfs2: introduce secondary super block nilfs2: simplify handling of active state of segments nilfs2: mark minor flag for checkpoint created by internal operation nilfs2: clean up sketch file nilfs2: super block operations fix endian bug ... Conflicts: arch/x86/include/asm/thread_info.h arch/x86/lguest/boot.c drivers/xen/manage.c
| * | | xen: clean up gate trap/interrupt constantsJeremy Fitzhardinge2009-03-301-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | Use GATE_INTERRUPT/TRAP rather than 0xe/f. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
| * | | xen: set _PAGE_NX in __supported_pte_mask before pagetable constructionJeremy Fitzhardinge2009-03-301-1/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Some 64-bit machines don't support the NX flag in ptes. Check for NX before constructing the kernel pagetables. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
| * | | xen/mmu: weaken flush_tlb_other testJeremy Fitzhardinge2009-03-301-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Impact: fixes crashing bug There's no particular problem with getting an empty cpu mask, so just shortcut-return if we get one. Avoids crash reported by Christophe Saout <christophe@saout.de> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
| * | | xen/mmu: some early pagetable cleanupsJeremy Fitzhardinge2009-03-302-14/+28
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 1. make sure early-allocated ptes are pinned, so they can be later unpinned 2. don't pin pmd+pud, just make them RO 3. scatter some __inits around Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
| * | | xen: mask XSAVE from cpuidJeremy Fitzhardinge2009-03-301-6/+44
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Xen leaves XSAVE set in cpuid, but doesn't allow cr4.OSXSAVE to be set. This confuses the kernel and it ends up crashing on an xsetbv instruction. At boot time, try to set cr4.OSXSAVE, and mask XSAVE out of cpuid it we can't. This will produce a spurious error from Xen, but allows us to support XSAVE if/when Xen does. This also factors out the cpuid mask decisions to boot time. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
| * | | NULL noise: arch/x86/xen/smp.cHannes Eder2009-03-301-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Fix this sparse warnings: arch/x86/xen/smp.c:316:52: warning: Using plain integer as NULL pointer arch/x86/xen/smp.c:421:60: warning: Using plain integer as NULL pointer Signed-off-by: Hannes Eder <hannes@hanneseder.net> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
| * | | xen: remove xen_load_gdt debugJeremy Fitzhardinge2009-03-301-3/+0Star
| | | | | | | | | | | | | | | | | | | | | | | | Don't need the noise. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
| * | | xen: make xen_load_gdt simplerJeremy Fitzhardinge2009-03-301-8/+6Star
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Remove use of multicall machinery which is unused (gdt loading is never performance critical). This removes the implicit use of percpu variables, which simplifies understanding how the percpu code's use of load_gdt interacts with this code. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
| * | | xen: clean up xen_load_gdtJeremy Fitzhardinge2009-03-301-2/+13
| | | | | | | | | | | | | | | | | | | | | | | | Makes the logic a bit clearer. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
| * | | xen: split construction of p2m mfn tables from registrationJeremy Fitzhardinge2009-03-301-1/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Build the p2m_mfn_list_list early with the rest of the p2m table, but register it later when the real shared_info structure is in place. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
| * | | xen: separate p2m allocation from settingJeremy Fitzhardinge2009-03-302-17/+47
| | | | | | | | | | | | | | | | | | | | | | | | | | | | When doing very early p2m setting, we need to separate setting from allocation, so split things up accordingly. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
| * | | xen: disable preempt for leave_lazy_mmuJeremy Fitzhardinge2009-03-301-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | xen_mc_flush() requires preemption to be disabled for its own sanity, so disable it while we're flushing. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
| * | | x86/paravirt: allow preemption with lazy mmu modeJeremy Fitzhardinge2009-03-301-7/+1Star
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Impact: remove obsolete checks, simplification Lift restrictions on preemption with lazy mmu mode, as it is now allowed. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
| * | | x86/paravirt: finish change from lazy cpu to context switch start/endJeremy Fitzhardinge2009-03-301-6/+4Star
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Impact: fix lazy context switch API Pass the previous and next tasks into the context switch start end calls, so that the called functions can properly access the task state (esp in end_context_switch, in which the next task is not yet completely current). Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
| * | | x86/paravirt: flush pending mmu updates on context switchJeremy Fitzhardinge2009-03-303-5/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Impact: allow preemption during lazy mmu updates If we're in lazy mmu mode when context switching, leave lazy mmu mode, but remember the task's state in TIF_LAZY_MMU_UPDATES. When we resume the task, check this flag and re-enter lazy mmu mode if its set. This sets things up for allowing lazy mmu mode while preemptible, though that won't actually be active until the next change. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
| * | | x86/pvops: replace arch_enter_lazy_cpu_mode with arch_start_context_switchJeremy Fitzhardinge2009-03-301-4/+1Star
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Impact: simplification, prepare for later changes Make lazy cpu mode more specific to context switching, so that it makes sense to do more context-switch specific things in the callbacks. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
* | | | x86: Fix performance regression caused by paravirt_ops on native kernelsJeremy Fitzhardinge2009-05-152-6/+18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Xiaohui Xin and some other folks at Intel have been looking into what's behind the performance hit of paravirt_ops when running native. It appears that the hit is entirely due to the paravirtualized spinlocks introduced by: | commit 8efcbab674de2bee45a2e4cdf97de16b8e609ac8 | Date: Mon Jul 7 12:07:51 2008 -0700 | | paravirt: introduce a "lock-byte" spinlock implementation The extra call/return in the spinlock path is somehow causing an increase in the cycles/instruction of somewhere around 2-7% (seems to vary quite a lot from test to test). The working theory is that the CPU's pipeline is getting upset about the call->call->locked-op->return->return, and seems to be failing to speculate (though I haven't seen anything definitive about the precise reasons). This doesn't entirely make sense, because the performance hit is also visible on unlock and other operations which don't involve locked instructions. But spinlock operations clearly swamp all the other pvops operations, even though I can't imagine that they're nearly as common (there's only a .05% increase in instructions executed). If I disable just the pv-spinlock calls, my tests show that pvops is identical to non-pvops performance on native (my measurements show that it is actually about .1% faster, but Xiaohui shows a .05% slowdown). Summary of results, averaging 10 runs of the "mmperf" test, using a no-pvops build as baseline: nopv Pv-nospin Pv-spin CPU cycles 100.00% 99.89% 102.18% instructions 100.00% 100.10% 100.15% CPI 100.00% 99.79% 102.03% cache ref 100.00% 100.84% 100.28% cache miss 100.00% 90.47% 88.56% cache miss rate 100.00% 89.72% 88.31% branches 100.00% 99.93% 100.04% branch miss 100.00% 103.66% 107.72% branch miss rt 100.00% 103.73% 107.67% wallclock 100.00% 99.90% 102.20% The clear effect here is that the 2% increase in CPI is directly reflected in the final wallclock time. (The other interesting effect is that the more ops are out of line calls via pvops, the lower the cache access and miss rates. Not too surprising, but it suggests that the non-pvops kernel is over-inlined. On the flipside, the branch misses go up correspondingly...) So, what's the fix? Paravirt patching turns all the pvops calls into direct calls, so _spin_lock etc do end up having direct calls. For example, the compiler generated code for paravirtualized _spin_lock is: <_spin_lock+0>: mov %gs:0xb4c8,%rax <_spin_lock+9>: incl 0xffffffffffffe044(%rax) <_spin_lock+15>: callq *0xffffffff805a5b30 <_spin_lock+22>: retq The indirect call will get patched to: <_spin_lock+0>: mov %gs:0xb4c8,%rax <_spin_lock+9>: incl 0xffffffffffffe044(%rax) <_spin_lock+15>: callq <__ticket_spin_lock> <_spin_lock+20>: nop; nop /* or whatever 2-byte nop */ <_spin_lock+22>: retq One possibility is to inline _spin_lock, etc, when building an optimised kernel (ie, when there's no spinlock/preempt instrumentation/debugging enabled). That will remove the outer call/return pair, returning the instruction stream to a single call/return, which will presumably execute the same as the non-pvops case. The downsides arel 1) it will replicate the preempt_disable/enable code at eack lock/unlock callsite; this code is fairly small, but not nothing; and 2) the spinlock definitions are already a very heavily tangled mass of #ifdefs and other preprocessor magic, and making any changes will be non-trivial. The other obvious answer is to disable pv-spinlocks. Making them a separate config option is fairly easy, and it would be trivial to enable them only when Xen is enabled (as the only non-default user). But it doesn't really address the common case of a distro build which is going to have Xen support enabled, and leaves the open question of whether the native performance cost of pv-spinlocks is worth the performance improvement on a loaded Xen system (10% saving of overall system CPU when guests block rather than spin). Still it is a reasonable short-term workaround. [ Impact: fix pvops performance regression when running native ] Analysed-by: "Xin Xiaohui" <xiaohui.xin@intel.com> Analysed-by: "Li Xin" <xin.li@intel.com> Analysed-by: "Nakajima Jun" <jun.nakajima@intel.com> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Acked-by: H. Peter Anvin <hpa@zytor.com> Cc: Nick Piggin <npiggin@suse.de> Cc: Xen-devel <xen-devel@lists.xensource.com> LKML-Reference: <4A0B62F7.5030802@goop.org> [ fixed the help text ] Signed-off-by: Ingo Molnar <mingo@elte.hu>
* | | | xen: use header for EXPORT_SYMBOL_GPLRandy Dunlap2009-05-131-0/+1
| |_|/ |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | mmu.c needs to #include module.h to prevent these warnings: arch/x86/xen/mmu.c:239: warning: data definition has no type or storage class arch/x86/xen/mmu.c:239: warning: type defaults to 'int' in declaration of 'EXPORT_SYMBOL_GPL' arch/x86/xen/mmu.c:239: warning: parameter names (without types) in function declaration [ Impact: cleanup ] Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com> Acked-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* | | x86: xen, i386: reserve Xen pagetablesJeremy Fitzhardinge2009-05-081-0/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The Xen pagetables are no longer implicitly reserved as part of the other i386_start_kernel reservations, so make sure we explicitly reserve them. This prevents them from being released into the general kernel free page pool and reused. [ Impact: fix Xen guest crash ] Also-Bisected-by: Bryan Donlan <bdonlan@gmail.com> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Cc: Xen-devel <xen-devel@lists.xensource.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> LKML-Reference: <4A032EEC.30509@goop.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* | | clocksource: pass clocksource to read() callbackMagnus Damm2009-04-211-1/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pass clocksource pointer to the read() callback for clocksources. This allows us to share the callback between multiple instances. [hugh@veritas.com: fix powerpc build of clocksource pass clocksource mods] [akpm@linux-foundation.org: cleanup] Signed-off-by: Magnus Damm <damm@igel.co.jp> Acked-by: John Stultz <johnstul@us.ibm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | | Merge branch 'for-rc1/xen/core' of ↵Linus Torvalds2009-04-145-57/+157
|\ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/jeremy/xen * 'for-rc1/xen/core' of git://git.kernel.org/pub/scm/linux/kernel/git/jeremy/xen: xen: add FIX_TEXT_POKE to fixmap xen: honour VCPU availability on boot xen: clean up gate trap/interrupt constants xen: set _PAGE_NX in __supported_pte_mask before pagetable construction xen: resume interrupts before system devices. xen/mmu: weaken flush_tlb_other test xen/mmu: some early pagetable cleanups Xen: Add virt_to_pfn helper function x86-64: remove PGE from must-have feature list xen: mask XSAVE from cpuid NULL noise: arch/x86/xen/smp.c xen: remove xen_load_gdt debug xen: make xen_load_gdt simpler xen: clean up xen_load_gdt xen: split construction of p2m mfn tables from registration xen: separate p2m allocation from setting xen: disable preempt for leave_lazy_mmu
| * | | xen: add FIX_TEXT_POKE to fixmapJeremy Fitzhardinge2009-04-091-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | FIX_TEXT_POKE[01] are used to map kernel addresses, so they're mapping pfns, not mfns. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
| * | | xen: clean up gate trap/interrupt constantsJeremy Fitzhardinge2009-04-081-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | Use GATE_INTERRUPT/TRAP rather than 0xe/f. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
| * | | xen: set _PAGE_NX in __supported_pte_mask before pagetable constructionJeremy Fitzhardinge2009-04-081-1/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Some 64-bit machines don't support the NX flag in ptes. Check for NX before constructing the kernel pagetables. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
| * | | xen/mmu: weaken flush_tlb_other testJeremy Fitzhardinge2009-04-081-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Impact: fixes crashing bug There's no particular problem with getting an empty cpu mask, so just shortcut-return if we get one. Avoids crash reported by Christophe Saout <christophe@saout.de> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
| * | | xen/mmu: some early pagetable cleanupsJeremy Fitzhardinge2009-04-082-14/+28
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 1. make sure early-allocated ptes are pinned, so they can be later unpinned 2. don't pin pmd+pud, just make them RO 3. scatter some __inits around Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
| * | | xen: mask XSAVE from cpuidJeremy Fitzhardinge2009-04-081-6/+44
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Xen leaves XSAVE set in cpuid, but doesn't allow cr4.OSXSAVE to be set. This confuses the kernel and it ends up crashing on an xsetbv instruction. At boot time, try to set cr4.OSXSAVE, and mask XSAVE out of cpuid it we can't. This will produce a spurious error from Xen, but allows us to support XSAVE if/when Xen does. This also factors out the cpuid mask decisions to boot time. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
| * | | NULL noise: arch/x86/xen/smp.cHannes Eder2009-04-081-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Fix this sparse warnings: arch/x86/xen/smp.c:316:52: warning: Using plain integer as NULL pointer arch/x86/xen/smp.c:421:60: warning: Using plain integer as NULL pointer Signed-off-by: Hannes Eder <hannes@hanneseder.net> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
| * | | xen: remove xen_load_gdt debugJeremy Fitzhardinge2009-04-081-3/+0Star
| | | | | | | | | | | | | | | | | | | | | | | | Don't need the noise. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
| * | | xen: make xen_load_gdt simplerJeremy Fitzhardinge2009-04-081-8/+6Star
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Remove use of multicall machinery which is unused (gdt loading is never performance critical). This removes the implicit use of percpu variables, which simplifies understanding how the percpu code's use of load_gdt interacts with this code. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
| * | | xen: clean up xen_load_gdtJeremy Fitzhardinge2009-04-081-2/+13
| | | | | | | | | | | | | | | | | | | | | | | | Makes the logic a bit clearer. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
| * | | xen: split construction of p2m mfn tables from registrationJeremy Fitzhardinge2009-04-081-1/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Build the p2m_mfn_list_list early with the rest of the p2m table, but register it later when the real shared_info structure is in place. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
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