lwn.git/arch/x86/kernel/kvm.c, branch v3.18.26

x86, kvm: Clear paravirt_enabled on KVM guests for espfix32's benefit

2015-01-08T18:30:15+00:00

commit 29fa6825463c97e5157284db80107d1bfac5d77b upstream. paravirt_enabled has the following effects: - Disables the F00F bug workaround warning. There is no F00F bug workaround any more because Linux's standard IDT handling already works around the F00F bug, but the warning still exists. This is only cosmetic, and, in any event, there is no such thing as KVM on a CPU with the F00F bug. - Disables 32-bit APM BIOS detection. On a KVM paravirt system, there should be no APM BIOS anyway. - Disables tboot. I think that the tboot code should check the CPUID hypervisor bit directly if it matters. - paravirt_enabled disables espfix32. espfix32 should *not* be disabled under KVM paravirt. The last point is the purpose of this patch. It fixes a leak of the high 16 bits of the kernel stack address on 32-bit KVM paravirt guests. Fixes CVE-2014-8134. Suggested-by: Konrad Rzeszutek Wilk Signed-off-by: Andy Lutomirski Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman

Merge branch 'for-3.18-consistent-ops' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu

2014-10-15T05:48:18+00:00

Pull percpu consistent-ops changes from Tejun Heo: "Way back, before the current percpu allocator was implemented, static and dynamic percpu memory areas were allocated and handled separately and had their own accessors. The distinction has been gone for many years now; however, the now duplicate two sets of accessors remained with the pointer based ones - this_cpu_*() - evolving various other operations over time. During the process, we also accumulated other inconsistent operations. This pull request contains Christoph's patches to clean up the duplicate accessor situation. __get_cpu_var() uses are replaced with with this_cpu_ptr() and __this_cpu_ptr() with raw_cpu_ptr(). Unfortunately, the former sometimes is tricky thanks to C being a bit messy with the distinction between lvalues and pointers, which led to a rather ugly solution for cpumask_var_t involving the introduction of this_cpu_cpumask_var_ptr(). This converts most of the uses but not all. Christoph will follow up with the remaining conversions in this merge window and hopefully remove the obsolete accessors" * 'for-3.18-consistent-ops' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu: (38 commits) irqchip: Properly fetch the per cpu offset percpu: Resolve ambiguities in __get_cpu_var/cpumask_var_t -fix ia64: sn_nodepda cannot be assigned to after this_cpu conversion. Use __this_cpu_write. percpu: Resolve ambiguities in __get_cpu_var/cpumask_var_t Revert "powerpc: Replace __get_cpu_var uses" percpu: Remove __this_cpu_ptr clocksource: Replace __this_cpu_ptr with raw_cpu_ptr sparc: Replace __get_cpu_var uses avr32: Replace __get_cpu_var with __this_cpu_write blackfin: Replace __get_cpu_var uses tile: Use this_cpu_ptr() for hardware counters tile: Replace __get_cpu_var uses powerpc: Replace __get_cpu_var uses alpha: Replace __get_cpu_var ia64: Replace __get_cpu_var uses s390: cio driver &__get_cpu_var replacements s390: Replace __get_cpu_var uses mips: Replace __get_cpu_var uses MIPS: Replace __get_cpu_var uses in FPU emulator. arm: Replace __this_cpu_ptr with raw_cpu_ptr ...

kvm: ensure hard lockup detection is disabled by default

2014-10-14T00:18:27+00:00

Use watchdog_enable_hardlockup_detector() to set hard lockup detection's default value to false. It's risky to run this detection in a guest, as false positives are easy to trigger, especially if the host is overcommitted. Signed-off-by: Ulrich Obergfell Signed-off-by: Andrew Jones Signed-off-by: Don Zickus Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

x86: Replace __get_cpu_var uses

2014-08-26T17:45:49+00:00

__get_cpu_var() is used for multiple purposes in the kernel source. One of them is address calculation via the form &__get_cpu_var(x). This calculates the address for the instance of the percpu variable of the current processor based on an offset. Other use cases are for storing and retrieving data from the current processors percpu area. __get_cpu_var() can be used as an lvalue when writing data or on the right side of an assignment. __get_cpu_var() is defined as : #define __get_cpu_var(var) (*this_cpu_ptr(&(var))) __get_cpu_var() always only does an address determination. However, store and retrieve operations could use a segment prefix (or global register on other platforms) to avoid the address calculation. this_cpu_write() and this_cpu_read() can directly take an offset into a percpu area and use optimized assembly code to read and write per cpu variables. This patch converts __get_cpu_var into either an explicit address calculation using this_cpu_ptr() or into a use of this_cpu operations that use the offset. Thereby address calculations are avoided and less registers are used when code is generated. Transformations done to __get_cpu_var() 1. Determine the address of the percpu instance of the current processor. DEFINE_PER_CPU(int, y); int *x = &__get_cpu_var(y); Converts to int *x = this_cpu_ptr(&y); 2. Same as #1 but this time an array structure is involved. DEFINE_PER_CPU(int, y[20]); int *x = __get_cpu_var(y); Converts to int *x = this_cpu_ptr(y); 3. Retrieve the content of the current processors instance of a per cpu variable. DEFINE_PER_CPU(int, y); int x = __get_cpu_var(y) Converts to int x = __this_cpu_read(y); 4. Retrieve the content of a percpu struct DEFINE_PER_CPU(struct mystruct, y); struct mystruct x = __get_cpu_var(y); Converts to memcpy(&x, this_cpu_ptr(&y), sizeof(x)); 5. Assignment to a per cpu variable DEFINE_PER_CPU(int, y) __get_cpu_var(y) = x; Converts to __this_cpu_write(y, x); 6. Increment/Decrement etc of a per cpu variable DEFINE_PER_CPU(int, y); __get_cpu_var(y)++ Converts to __this_cpu_inc(y) Cc: Thomas Gleixner Cc: x86@kernel.org Acked-by: H. Peter Anvin Acked-by: Ingo Molnar Signed-off-by: Christoph Lameter Signed-off-by: Tejun Heo

Merge branch 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2014-06-13T02:18:49+00:00

Pull more perf updates from Ingo Molnar: "A second round of perf updates: - wide reaching kprobes sanitization and robustization, with the hope of fixing all 'probe this function crashes the kernel' bugs, by Masami Hiramatsu. - uprobes updates from Oleg Nesterov: tmpfs support, corner case fixes and robustization work. - perf tooling updates and fixes from Jiri Olsa, Namhyung Ki, Arnaldo et al: * Add support to accumulate hist periods (Namhyung Kim) * various fixes, refactorings and enhancements" * 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (101 commits) perf: Differentiate exec() and non-exec() comm events perf: Fix perf_event_comm() vs. exec() assumption uprobes/x86: Rename arch_uprobe->def to ->defparam, minor comment updates perf/documentation: Add description for conditional branch filter perf/x86: Add conditional branch filtering support perf/tool: Add conditional branch filter 'cond' to perf record perf: Add new conditional branch filter 'PERF_SAMPLE_BRANCH_COND' uprobes: Teach copy_insn() to support tmpfs uprobes: Shift ->readpage check from __copy_insn() to uprobe_register() perf/x86: Use common PMU interrupt disabled code perf/ARM: Use common PMU interrupt disabled code perf: Disable sampled events if no PMU interrupt perf: Fix use after free in perf_remove_from_context() perf tools: Fix 'make help' message error perf record: Fix poll return value propagation perf tools: Move elide bool into perf_hpp_fmt struct perf tools: Remove elide setup for SORT_MODE__MEMORY mode perf tools: Fix "==" into "=" in ui_browser__warning assignment perf tools: Allow overriding sysfs and proc finding with env var perf tools: Consider header files outside perf directory in tags target ...

x86: fix page fault tracing when KVM guest support enabled

2014-05-22T15:47:17+00:00

I noticed on some of my systems that page fault tracing doesn't work: cd /sys/kernel/debug/tracing echo 1 > events/exceptions/enable cat trace; # nothing shows up I eventually traced it down to CONFIG_KVM_GUEST. At least in a KVM VM, enabling that option breaks page fault tracing, and disabling fixes it. I tried on some old kernels and this does not appear to be a regression: it never worked. There are two page-fault entry functions today. One when tracing is on and another when it is off. The KVM code calls do_page_fault() directly instead of calling the traced version: > dotraplinkage void __kprobes > do_async_page_fault(struct pt_regs *regs, unsigned long > error_code) > { > enum ctx_state prev_state; > > switch (kvm_read_and_reset_pf_reason()) { > default: > do_page_fault(regs, error_code); > break; > case KVM_PV_REASON_PAGE_NOT_PRESENT: I'm also having problems with the page fault tracing on bare metal (same symptom of no trace output). I'm unsure if it's related. Steven had an alternative to this which has zero overhead when tracing is off where this includes the standard noops even when tracing is disabled. I'm unconvinced that the extra complexity of his apporach: http://lkml.kernel.org/r/20140508194508.561ed220@gandalf.local.home is worth it, expecially considering that the KVM code is already making page fault entry slower here. This solution is dirt-simple. Cc: Thomas Gleixner Cc: x86@kernel.org Cc: Peter Zijlstra Cc: Gleb Natapov Cc: kvm@vger.kernel.org Cc: Paolo Bonzini Signed-off-by: Dave Hansen Acked-by: "H. Peter Anvin" Acked-by: Steven Rostedt Signed-off-by: Paolo Bonzini

kprobes, x86: Use NOKPROBE_SYMBOL() instead of __kprobes annotation

2014-04-24T08:26:38+00:00

Use NOKPROBE_SYMBOL macro for protecting functions from kprobes instead of __kprobes annotation under arch/x86. This applies nokprobe_inline annotation for some cases, because NOKPROBE_SYMBOL() will inhibit inlining by referring the symbol address. This just folds a bunch of previous NOKPROBE_SYMBOL() cleanup patches for x86 to one patch. Signed-off-by: Masami Hiramatsu Link: http://lkml.kernel.org/r/20140417081814.26341.51656.stgit@ltc230.yrl.intra.hitachi.co.jp Cc: Andrew Morton Cc: Arnaldo Carvalho de Melo Cc: Borislav Petkov Cc: Dave Hansen Cc: Fernando Luis Vázquez Cao Cc: Gleb Natapov Cc: Jason Wang Cc: Jesper Nilsson Cc: Jiri Kosina Cc: Jiri Olsa Cc: Jiri Slaby Cc: Johannes Weiner Cc: Jonathan Lebon Cc: Kees Cook Cc: Matt Fleming Cc: Michel Lespinasse Cc: Paolo Bonzini Cc: Paul E. McKenney Cc: Paul Gortmaker Cc: Paul Mackerras Cc: Raghavendra K T Cc: Rusty Russell Cc: Seiji Aguchi Cc: Srivatsa Vaddagiri Cc: Tejun Heo Cc: Vineet Gupta Signed-off-by: Ingo Molnar

kvm: remove redundant registration of BSP's hv_clock area

2014-02-22T14:53:32+00:00

These days hv_clock allocation is memblock based (i.e. the percpu allocator is not involved), which means that the physical address of each of the per-cpu hv_clock areas is guaranteed to remain unchanged through all its lifetime and we do not need to update its location after CPU bring-up. Signed-off-by: Fernando Luis Vazquez Cao Signed-off-by: Paolo Bonzini

Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

2014-01-31T16:37:32+00:00

Pull more KVM updates from Paolo Bonzini: "Second batch of KVM updates. Some minor x86 fixes, two s390 guest features that need some handling in the host, and all the PPC changes. The PPC changes include support for little-endian guests and enablement for new POWER8 features" * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (45 commits) x86, kvm: correctly access the KVM_CPUID_FEATURES leaf at 0x40000101 x86, kvm: cache the base of the KVM cpuid leaves kvm: x86: move KVM_CAP_HYPERV_TIME outside #ifdef KVM: PPC: Book3S PR: Cope with doorbell interrupts KVM: PPC: Book3S HV: Add software abort codes for transactional memory KVM: PPC: Book3S HV: Add new state for transactional memory powerpc/Kconfig: Make TM select VSX and VMX KVM: PPC: Book3S HV: Basic little-endian guest support KVM: PPC: Book3S HV: Add support for DABRX register on POWER7 KVM: PPC: Book3S HV: Prepare for host using hypervisor doorbells KVM: PPC: Book3S HV: Handle new LPCR bits on POWER8 KVM: PPC: Book3S HV: Handle guest using doorbells for IPIs KVM: PPC: Book3S HV: Consolidate code that checks reason for wake from nap KVM: PPC: Book3S HV: Implement architecture compatibility modes for POWER8 KVM: PPC: Book3S HV: Add handler for HV facility unavailable KVM: PPC: Book3S HV: Flush the correct number of TLB sets on POWER8 KVM: PPC: Book3S HV: Context-switch new POWER8 SPRs KVM: PPC: Book3S HV: Align physical and virtual CPU thread numbers KVM: PPC: Book3S HV: Don't set DABR on POWER8 kvm/ppc: IRQ disabling cleanup ...

x86, asmlinkage, xen, kvm: Make {xen,kvm}_lock_spinning global and visible

2014-01-30T06:17:18+00:00

These functions are called from inline assembler stubs, thus need to be global and visible. Cc: Konrad Rzeszutek Wilk Cc: Gleb Natapov Cc: Raghavendra K T Signed-off-by: Andi Kleen Link: http://lkml.kernel.org/r/1382458079-24450-7-git-send-email-andi@firstfloor.org Signed-off-by: H. Peter Anvin