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2016-09-20KVM: x86: introduce get_kvmclock_nsPaolo Bonzini1-2/+3
Introduce a function that reads the exact nanoseconds value that is provided to the guest in kvmclock. This crystallizes the notion of kvmclock as a thin veneer over a stable TSC, that the guest will (hopefully) convert with NTP. In other words, kvmclock is *not* a paravirtualized host-to-guest NTP. Drop the get_kernel_ns() function, that was used both to get the base value of the master clock and to get the current value of kvmclock. The former use is replaced by ktime_get_boot_ns(), the latter is the purpose of get_kernel_ns(). This also allows KVM to provide a Hyper-V time reference counter that is synchronized with the time that is computed from the TSC page. Reviewed-by: Roman Kagan <rkagan@virtuozzo.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-08-04pvclock: introduce seqcount-like APIPaolo Bonzini1-16/+23
The version field in struct pvclock_vcpu_time_info basically implements a seqcount. Wrap it with the usual read_begin and read_retry functions, and use these APIs instead of peppering the code with smp_rmb()s. While at it, change it to the more pedantically correct virt_rmb(). With this change, __pvclock_read_cycles can be simplified noticeably. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-06-27pvclock: Cleanup to remove function pvclock_get_nsec_offsetMinfei Huang1-16/+7
Function __pvclock_read_cycles is short enough, so there is no need to have another function pvclock_get_nsec_offset to calculate tsc delta. It's better to combine it into function __pvclock_read_cycles. Remove useless variables in function __pvclock_read_cycles. Signed-off-by: Minfei Huang <mnghuan@gmail.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-06-27pvclock: Add CPU barriers to get correct version valueMinfei Huang1-0/+2
Protocol for the "version" fields is: hypervisor raises it (making it uneven) before it starts updating the fields and raises it again (making it even) when it is done. Thus the guest can make sure the time values it got are consistent by checking the version before and after reading them. Add CPU barries after getting version value just like what function vread_pvclock does, because all of callees in this function is inline. Fixes: 502dfeff239e8313bfbe906ca0a1a6827ac8481b Cc: stable@vger.kernel.org Signed-off-by: Minfei Huang <mnghuan@gmail.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-01-06x86/vsdo: Fix build on PARAVIRT_CLOCK=y, KVM_GUEST=nAndy Lutomirski1-1/+1
arch/x86/built-in.o: In function `arch_setup_additional_pages': (.text+0x587): undefined reference to `pvclock_pvti_cpu0_va' KVM_GUEST selects PARAVIRT_CLOCK, so we can make pvclock_pvti_cpu0_va depend on KVM_GUEST. Signed-off-by: Andy Lutomirski <luto@kernel.org> Tested-by: Borislav Petkov <bp@alien8.de> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Kees Cook <keescook@chromium.org> Link: http://lkml.kernel.org/r/444d38a9bcba832685740ea1401b569861d09a72.1451446564.git.luto@kernel.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2015-12-11x86/vdso: Remove pvclock fixmap machineryAndy Lutomirski1-5/+0
Signed-off-by: Andy Lutomirski <luto@kernel.org> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/4933029991103ae44672c82b97a20035f5c1fe4f.1449702533.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-12-11x86/vdso: Get pvclock data from the vvar VMA instead of the fixmapAndy Lutomirski1-0/+9
Signed-off-by: Andy Lutomirski <luto@kernel.org> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/9d37826fdc7e2d2809efe31d5345f97186859284.1449702533.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-06x86/asm/tsc, x86/kvm: Drop open-coded barrier and use rdtsc_ordered() in kvmclockAndy Lutomirski1-8/+2
__pvclock_read_cycles() used to have two barriers, one of which was unnecessary, which got removed after an initial version of this patch was sent. But the barrier is still open-coded unnecessarily - get rid of that barrier and clean up the code by just using rdtsc_ordered(). Signed-off-by: Andy Lutomirski <luto@kernel.org> Signed-off-by: Borislav Petkov <bp@suse.de> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Huang Rui <ray.huang@amd.com> Cc: John Stultz <john.stultz@linaro.org> Cc: Len Brown <lenb@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Radim Krcmar <rkrcmar@redhat.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: kvm ML <kvm@vger.kernel.org> Link: http://lkml.kernel.org/r/678981cc4761fb38a793c217c9cac42503cf3719.1434501121.git.luto@kernel.org [ Ported it to v4.2-rc1. ] Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-06x86/asm/tsc: Rename native_read_tsc() to rdtsc()Andy Lutomirski1-1/+1
Now that there is no paravirt TSC, the "native" is inappropriate. The function does RDTSC, so give it the obvious name: rdtsc(). Suggested-by: Borislav Petkov <bp@suse.de> Signed-off-by: Andy Lutomirski <luto@kernel.org> Signed-off-by: Borislav Petkov <bp@suse.de> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Huang Rui <ray.huang@amd.com> Cc: John Stultz <john.stultz@linaro.org> Cc: Len Brown <lenb@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: kvm ML <kvm@vger.kernel.org> Link: http://lkml.kernel.org/r/fd43e16281991f096c1e4d21574d9e1402c62d39.1434501121.git.luto@kernel.org [ Ported it to v4.2-rc1. ] Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-06x86/asm/tsc: Inline native_read_tsc() and remove __native_read_tsc()Andy Lutomirski1-1/+1
In the following commit: cdc7957d1954 ("x86: move native_read_tsc() offline") ... native_read_tsc() was moved out of line, presumably for some now-obsolete vDSO-related reason. Undo it. The entire rdtsc, shl, or sequence is only 11 bytes, and calls via rdtscl() and similar helpers were already inlined. Signed-off-by: Andy Lutomirski <luto@kernel.org> Signed-off-by: Borislav Petkov <bp@suse.de> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Huang Rui <ray.huang@amd.com> Cc: John Stultz <john.stultz@linaro.org> Cc: Len Brown <lenb@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: kvm ML <kvm@vger.kernel.org> Link: http://lkml.kernel.org/r/d05ffe2aaf8468ca475ebc00efad7b2fa174af19.1434501121.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-05-07x86: kvmclock: drop rdtsc_barrier()Marcelo Tosatti1-1/+0
Drop unnecessary rdtsc_barrier(), as has been determined empirically, see 057e6a8c660e95c3f4e7162e00e2fee1fc90c50d for details. Noticed by Andy Lutomirski. Improves clock_gettime() by approximately 15% on Intel i7-3520M @ 2.90GHz. Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-04-27x86: pvclock: Really remove the sched notifier for cross-cpu migrationsPaolo Bonzini1-1/+0
This reverts commits 0a4e6be9ca17c54817cf814b4b5aa60478c6df27 and 80f7fdb1c7f0f9266421f823964fd1962681f6ce. The task migration notifier was originally introduced in order to support the pvclock vsyscall with non-synchronized TSC, but KVM only supports it with synchronized TSC. Hence, on KVM the race condition is only needed due to a bad implementation on the host side, and even then it's so rare that it's mostly theoretical. As far as KVM is concerned it's possible to fix the host, avoiding the additional complexity in the vDSO and the (re)introduction of the task migration notifier. Xen, on the other hand, hasn't yet implemented vsyscall support at all, so we do not care about its plans for non-synchronized TSC. Reported-by: Peter Zijlstra <peterz@infradead.org> Suggested-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-03-23x86: kvm: Revert "remove sched notifier for cross-cpu migrations"Marcelo Tosatti1-0/+1
The following point: 2. per-CPU pvclock time info is updated if the underlying CPU changes. Is not true anymore since "KVM: x86: update pvclock area conditionally, on cpu migration". Add task migration notification back. Problem noticed by Andy Lutomirski. Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> CC: stable@kernel.org # 3.11+
2013-11-06pvclock: detect watchdog reset at pvclock readMarcelo Tosatti1-0/+2
Implement reset of kernel watchdogs at pvclock read time. This avoids adding special code to every watchdog. This is possible for watchdogs which measure time based on sched_clock() or ktime_get() variants. Suggested by Don Zickus. Acked-by: Don Zickus <dzickus@redhat.com> Acked-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Gleb Natapov <gleb@redhat.com>
2013-07-18remove sched notifier for cross-cpu migrationsMarcelo Tosatti1-1/+0
Linux as a guest on KVM hypervisor, the only user of the pvclock vsyscall interface, does not require notification on task migration because: 1. cpu ID number maps 1:1 to per-CPU pvclock time info. 2. per-CPU pvclock time info is updated if the underlying CPU changes. 3. that version is increased whenever underlying CPU changes. Which is sufficient to guarantee nanoseconds counter is calculated properly. Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Gleb Natapov <gleb@redhat.com>
2012-11-27x86: pvclock: generic pvclock vsyscall initializationMarcelo Tosatti1-0/+12
Originally from Jeremy Fitzhardinge. Introduce generic, non hypervisor specific, pvclock initialization routines. Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2012-11-27x86: pvclock: add note about rdtsc barriersMarcelo Tosatti1-0/+6
As noted by Gleb, not advertising SSE2 support implies no RDTSC barriers. Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2012-11-27x86: pvclock: introduce helper to read flagsMarcelo Tosatti1-0/+1
Acked-by: Glauber Costa <glommer@parallels.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2012-11-27x86: pvclock: create helper for pvclock data retrievalMarcelo Tosatti1-0/+28
Originally from Jeremy Fitzhardinge. So code can be reused. Acked-by: Glauber Costa <glommer@parallels.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2011-08-30KVM: Fix instruction size issue in pvclock scalingDuncan Sands1-1/+1
Commit de2d1a524e94 ("KVM: Fix register corruption in pvclock_scale_delta") introduced a mul instruction that may have only a memory operand; the assembler therefore cannot select the correct size: pvclock.s:229: Error: no instruction mnemonic suffix given and no register operands; can't size instruction In this example the assembler is: #APP mul -48(%rbp) ; shrd $32, %rdx, %rax #NO_APP A simple solution is to use mulq. Signed-off-by: Duncan Sands <baldrick@free.fr> Signed-off-by: Avi Kivity <avi@redhat.com>
2011-06-19KVM: Fix register corruption in pvclock_scale_deltaZachary Amsden1-2/+7
The 128-bit multiply in pvclock.h was missing an output constraint for EDX which caused a register corruption to appear. Thanks to Ulrich for diagnosing the EDX corruption and Avi for providing this fix. Signed-off-by: Zachary Amsden <zamsden@redhat.com> Signed-off-by: Avi Kivity <avi@redhat.com>
2010-11-28x86/pvclock: Zero last_value on resumeJeremy Fitzhardinge1-0/+1
If the guest domain has been suspend/resumed or migrated, then the system clock backing the pvclock clocksource may revert to a smaller value (ie, can be non-monotonic across the migration/save-restore). Make sure we zero last_value in that case so that the domain continues to see clock updates. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-10-24x86: pvclock: Move scale_delta into common headerZachary Amsden1-0/+38
The scale_delta function for shift / multiply with 31-bit precision moves to a common header so it can be used by both kernel and kvm module. Signed-off-by: Zachary Amsden <zamsden@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2010-05-19x86, paravirt: Enable pvclock flags in vcpu_time_info structureGlauber Costa1-0/+1
This patch removes one padding byte and transform it into a flags field. New versions of guests using pvclock will query these flags upon each read. Flags, however, will only be interpreted when the guest decides to. It uses the pvclock_valid_flags function to signal that a specific set of flags should be taken into consideration. Which flags are valid are usually devised via HV negotiation. Signed-off-by: Glauber Costa <glommer@redhat.com> CC: Jeremy Fitzhardinge <jeremy@goop.org> Acked-by: Zachary Amsden <zamsden@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2008-10-22x86: Fix ASM_X86__ header guardsH. Peter Anvin1-3/+3
Change header guards named "ASM_X86__*" to "_ASM_X86_*" since: a. the double underscore is ugly and pointless. b. no leading underscore violates namespace constraints. Signed-off-by: H. Peter Anvin <hpa@zytor.com>
2008-10-22x86, um: ... and asm-x86 moveAl Viro1-0/+14
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
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