The 5-patch series to follow this email extends KVM-hypervisor and Linux guest running on KVM-hypervisor to support pv-ticket spinlocks, based on Xen's implementation. One hypercall is introduced in KVM hypervisor,that allows a vcpu to kick another vcpu out of halt state. The blocking of vcpu is done using halt() in (lock_spinning) slowpath. Note: 1) patch is based on 3.4-rc3 + ticketlock patches in https://lkml.org/lkml/2012/4/19/335 [ The patches are targeted for 3.5 window ] Changes in V6: - Rebased to 3.4-rc3 - Removed debugfs changes patch which should now be in Xen/linux-next. (https://lkml.org/lkml/2012/3/30/687) - Removed PV_UNHALT_MSR since currently we don't need guest communication, and made pv_unhalt folded to GET_MP_STATE (Marcello, Avi[long back]) - Take jumplabel changes from Ingo/Jason into use (static_key_slow_inc usage) - Added inline to spinlock_init in non PARAVIRT case - Move arch specific code to arch/x86 and add stubs to other archs (Marcello) - Added more comments on pv_unhalt usage etc (Marcello) Changes in V5: - rebased to 3.3-rc6 - added PV_UNHALT_MSR that would help in live migration (Avi) - removed PV_LOCK_KICK vcpu request and pv_unhalt flag (re)added. - Changed hypercall documentaion (Alex). - mode_t changed to umode_t in debugfs. - MSR related documentation added. - rename PV_LOCK_KICK to PV_UNHALT. - host and guest patches not mixed. (Marcelo, Alex) - kvm_kick_cpu now takes cpu so it can be used by flush_tlb_ipi_other paravirtualization (Nikunj) - coding style changes in variable declarion etc (Srikar) Changes in V4: - reabsed to 3.2.0 pre. - use APIC ID for kicking the vcpu and use kvm_apic_match_dest for matching (Avi) - fold vcpu->kicked flag into vcpu->requests (KVM_REQ_PVLOCK_KICK) and related changes for UNHALT path to make pv ticket spinlock migration friendly(Avi, Marcello) - Added Documentation for CPUID, Hypercall (KVM_HC_KICK_CPU) and capabilty (KVM_CAP_PVLOCK_KICK) (Avi) - Remove unneeded kvm_arch_vcpu_ioctl_set_mpstate call. (Marcello) - cumulative variable type changed (int ==> u32) in add_stat (Konrad) - remove unneeded kvm_guest_init for !CONFIG_KVM_GUEST case Changes in V3: - rebased to 3.2-rc1 - use halt() instead of wait for kick hypercall. - modify kick hyper call to do wakeup halted vcpu. - hook kvm_spinlock_init to smp_prepare_cpus call (moved the call out of head##.c). - fix the potential race when zero_stat is read. - export debugfs_create_32 and add documentation to API. - use static inline and enum instead of ADDSTAT macro. - add barrier() in after setting kick_vcpu. - empty static inline function for kvm_spinlock_init. - combine the patches one and two readuce overhead. - make KVM_DEBUGFS depends on DEBUGFS. - include debugfs header unconditionally. Changes in V2: - rebased patchesto -rc9 - synchronization related changes based on Jeremy's changes (Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>) pointed by Stephan Diestelhorst <stephan.diestelhorst@xxxxxxx> - enabling 32 bit guests - splitted patches into two more chunks Results: results for PLE / non PLE machine were posted for V5 patches in https://lkml.org/lkml/2012/3/23/50 https://lkml.org/lkml/2012/4/5/73 Current series is giving similar results but more formal results will be posted in next couple of days. Interestingly with current patchset I do not see CPU stalls observed in vanilla. TODO: 1) remove CONFIG_PARAVIRT_SPINLOCK ? 2) experiments on further optimization possibilities. (discussed in V6 of ticketlock) 3) possible debugfs cleanups (combining common code of Xen/KVM) Let me know if you have any sugestion/comments... --- V5 kernel changes: https://lkml.org/lkml/2012/3/23/50 Qemu changes for V5: http://lists.gnu.org/archive/html/qemu-devel/2012-03/msg04455.html V4 kernel changes: https://lkml.org/lkml/2012/1/14/66 Qemu changes for V4: http://www.mail-archive.com/kvm@xxxxxxxxxxxxxxx/msg66450.html V3 kernel Changes: https://lkml.org/lkml/2011/11/30/62 V2 kernel changes : https://lkml.org/lkml/2011/10/23/207 Previous discussions : (posted by Srivatsa V). https://lkml.org/lkml/2010/7/26/24 https://lkml.org/lkml/2011/1/19/212 Qemu patch for V3: http://lists.gnu.org/archive/html/qemu-devel/2011-12/msg00397.html Srivatsa Vaddagiri (3): Add a hypercall to KVM hypervisor to support pv-ticketlocks Added configuration support to enable debug information for KVM Guests pv-ticketlock support for linux guests running on KVM hypervisor Raghavendra K T (2): Fold pv_unhalt flag into GET_MP_STATE ioctl to aid migration Add documentation on Hypercalls and features used for PV spinlock Documentation/virtual/kvm/api.txt | 7 + Documentation/virtual/kvm/cpuid.txt | 4 + Documentation/virtual/kvm/hypercalls.txt | 59 +++++++ arch/ia64/include/asm/kvm_host.h | 3 + arch/powerpc/include/asm/kvm_host.h | 4 + arch/s390/include/asm/kvm_host.h | 4 + arch/x86/Kconfig | 9 + arch/x86/include/asm/kvm_host.h | 6 + arch/x86/include/asm/kvm_para.h | 16 ++- arch/x86/kernel/kvm.c | 254 ++++++++++++++++++++++++++++++ arch/x86/kvm/cpuid.c | 3 +- arch/x86/kvm/x86.c | 46 ++++++- include/linux/kvm.h | 1 + include/linux/kvm_para.h | 1 + virt/kvm/kvm_main.c | 8 + 15 files changed, 421 insertions(+), 4 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
