* [PATCH v2 0/2] Enable PV qspinlock for Hyper-V @ 2018-09-21 7:25 Yi Sun 2018-09-21 7:25 ` [PATCH v2 1/2] X86/Hyper-V: Add Guest IDLE MSR support Yi Sun 2018-09-21 7:25 ` [PATCH v2 2/2] locking/pvqspinlock, hv: Enable PV qspinlock for Hyper-V Yi Sun 0 siblings, 2 replies; 9+ messages in thread From: Yi Sun @ 2018-09-21 7:25 UTC (permalink / raw) To: linux-kernel Cc: x86, tglx, chao.p.peng, chao.gao, isaku.yamahata, michael.h.kelley, tianyu.lan, Yi Sun, K. Y. Srinivasan, Haiyang Zhang, Stephen Hemminger, Jonathan Corbet v1->v2: - compile hv_spinlock.c only when CONFIG_PARAVIRT_SPINLOCKS enabled - merge v1 patch 2/3 to single patch - remove part of the boilerplate in hv_spinlock.c - declare hv_pvspin as __initdata - remove spin_wait_info and hv_notify_long_spin_wait because SpinWaitInfo is a standalone feature. - add comments for reading HV_X64_MSR_GUEST_IDLE - replace pr_warn to pr_info - use pr_fmt instead of the 'hv:' prefix - register callback function for smp_ops.smp_prepare_boot_cpu to initialize hyper-v spinlock This patch adds the necessary Hyper-V specific code to allow PV qspinlock work on Hyper-V. In wait callback function, read HV_X64_MSR_GUEST_IDLE MSR to trigger the guest's transition to the idle power state which can be exited by an IPI even if IF flag is disabled. In kick callback function, just send platform IPI to make waiting vcpu exit idle state. In vcpu_is_preempted callback function, return false directly because Hyper-V does not provide such interface so far. Cc: "K. Y. Srinivasan" <kys@microsoft.com> Cc: Haiyang Zhang <haiyangz@microsoft.com> Cc: Stephen Hemminger <sthemmin@microsoft.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Thomas Gleixner <tglx@linutronix.de> Yi Sun (2): X86/Hyper-V: Add Guest IDLE MSR support locking/pvqspinlock, hv: Enable PV qspinlock for Hyper-V Documentation/admin-guide/kernel-parameters.txt | 5 ++ arch/x86/hyperv/Makefile | 4 ++ arch/x86/hyperv/hv_spinlock.c | 81 +++++++++++++++++++++++++ arch/x86/include/asm/hyperv-tlfs.h | 5 ++ arch/x86/include/asm/mshyperv.h | 3 + arch/x86/kernel/cpu/mshyperv.c | 12 ++++ 6 files changed, 110 insertions(+) create mode 100644 arch/x86/hyperv/hv_spinlock.c -- 1.9.1 ^ permalink raw reply [flat|nested] 9+ messages in thread
* [PATCH v2 1/2] X86/Hyper-V: Add Guest IDLE MSR support 2018-09-21 7:25 [PATCH v2 0/2] Enable PV qspinlock for Hyper-V Yi Sun @ 2018-09-21 7:25 ` Yi Sun 2018-09-21 16:52 ` Michael Kelley (EOSG) 2018-09-21 7:25 ` [PATCH v2 2/2] locking/pvqspinlock, hv: Enable PV qspinlock for Hyper-V Yi Sun 1 sibling, 1 reply; 9+ messages in thread From: Yi Sun @ 2018-09-21 7:25 UTC (permalink / raw) To: linux-kernel Cc: x86, tglx, chao.p.peng, chao.gao, isaku.yamahata, michael.h.kelley, tianyu.lan, Yi Sun, K. Y. Srinivasan, Haiyang Zhang, Stephen Hemminger Hyper-V may expose a HV_X64_MSR_GUEST_IDLE MSR. We can read HYPERV_CPUID_FEATURES eax to check it. Read this MSR can trigger the guest's transition to the idle power state which can be exited by an IPI even if IF flag is disabled. Cc: "K. Y. Srinivasan" <kys@microsoft.com> Cc: Haiyang Zhang <haiyangz@microsoft.com> Cc: Stephen Hemminger <sthemmin@microsoft.com> Signed-off-by: Yi Sun <yi.y.sun@linux.intel.com> --- arch/x86/include/asm/hyperv-tlfs.h | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h index e977b6b..2a2fa17 100644 --- a/arch/x86/include/asm/hyperv-tlfs.h +++ b/arch/x86/include/asm/hyperv-tlfs.h @@ -38,6 +38,8 @@ #define HV_MSR_TIME_REF_COUNT_AVAILABLE (1 << 1) /* Partition reference TSC MSR is available */ #define HV_MSR_REFERENCE_TSC_AVAILABLE (1 << 9) +/* Partition Guest IDLE MSR is available */ +#define HV_X64_MSR_GUEST_IDLE_AVAILABLE (1 << 10) /* A partition's reference time stamp counter (TSC) page */ #define HV_X64_MSR_REFERENCE_TSC 0x40000021 @@ -246,6 +248,9 @@ #define HV_X64_MSR_STIMER3_CONFIG 0x400000B6 #define HV_X64_MSR_STIMER3_COUNT 0x400000B7 +/* Hyper-V guest idle MSR */ +#define HV_X64_MSR_GUEST_IDLE 0x400000F0 + /* Hyper-V guest crash notification MSR's */ #define HV_X64_MSR_CRASH_P0 0x40000100 #define HV_X64_MSR_CRASH_P1 0x40000101 -- 1.9.1 ^ permalink raw reply related [flat|nested] 9+ messages in thread
* RE: [PATCH v2 1/2] X86/Hyper-V: Add Guest IDLE MSR support 2018-09-21 7:25 ` [PATCH v2 1/2] X86/Hyper-V: Add Guest IDLE MSR support Yi Sun @ 2018-09-21 16:52 ` Michael Kelley (EOSG) 0 siblings, 0 replies; 9+ messages in thread From: Michael Kelley (EOSG) @ 2018-09-21 16:52 UTC (permalink / raw) To: Yi Sun, linux-kernel Cc: x86, tglx, chao.p.peng, chao.gao, isaku.yamahata, Tianyu Lan, KY Srinivasan, Haiyang Zhang, Stephen Hemminger From: Yi Sun <yi.y.sun@linux.intel.com> Sent: Friday, September 21, 2018 12:25 AM > > Hyper-V may expose a HV_X64_MSR_GUEST_IDLE MSR. We can read > HYPERV_CPUID_FEATURES eax to check it. Read this MSR can > trigger the guest's transition to the idle power state which > can be exited by an IPI even if IF flag is disabled. > > Cc: "K. Y. Srinivasan" <kys@microsoft.com> > Cc: Haiyang Zhang <haiyangz@microsoft.com> > Cc: Stephen Hemminger <sthemmin@microsoft.com> > Signed-off-by: Yi Sun <yi.y.sun@linux.intel.com> > --- > arch/x86/include/asm/hyperv-tlfs.h | 5 +++++ > 1 file changed, 5 insertions(+) > Reviewed-by: Michael Kelley <mikelley@microsoft.com> ^ permalink raw reply [flat|nested] 9+ messages in thread
* [PATCH v2 2/2] locking/pvqspinlock, hv: Enable PV qspinlock for Hyper-V 2018-09-21 7:25 [PATCH v2 0/2] Enable PV qspinlock for Hyper-V Yi Sun 2018-09-21 7:25 ` [PATCH v2 1/2] X86/Hyper-V: Add Guest IDLE MSR support Yi Sun @ 2018-09-21 7:25 ` Yi Sun 2018-09-21 17:02 ` Michael Kelley (EOSG) ` (3 more replies) 1 sibling, 4 replies; 9+ messages in thread From: Yi Sun @ 2018-09-21 7:25 UTC (permalink / raw) To: linux-kernel Cc: x86, tglx, chao.p.peng, chao.gao, isaku.yamahata, michael.h.kelley, tianyu.lan, Yi Sun, K. Y. Srinivasan, Haiyang Zhang, Stephen Hemminger Follow PV spinlock mechanism to implement the callback functions to allow the CPU idling and kicking operations on Hyper-V. Cc: "K. Y. Srinivasan" <kys@microsoft.com> Cc: Haiyang Zhang <haiyangz@microsoft.com> Cc: Stephen Hemminger <sthemmin@microsoft.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Yi Sun <yi.y.sun@linux.intel.com> --- v1->v2: - compile hv_spinlock.c only when CONFIG_PARAVIRT_SPINLOCKS enabled - merge v1 patch 2/3 to single patch (suggested by Thomas Gleixner) - remove part of the boilerplate in hv_spinlock.c (suggested by Thomas Gleixner) - declare hv_pvspin as __initdata (suggested by Thomas Gleixner) - remove spin_wait_info and hv_notify_long_spin_wait because SpinWaitInfo is a standalone feature. - add comments for reading HV_X64_MSR_GUEST_IDLE (suggested by Thomas Gleixner) - replace pr_warn to pr_info (suggested by Thomas Gleixner) - use pr_fmt instead of the 'hv:' prefix (suggested by Thomas Gleixner) - register callback function for smp_ops.smp_prepare_boot_cpu to initialize hyper-v spinlock (suggested by Thomas Gleixner) --- Documentation/admin-guide/kernel-parameters.txt | 5 ++ arch/x86/hyperv/Makefile | 4 ++ arch/x86/hyperv/hv_spinlock.c | 81 +++++++++++++++++++++++++ arch/x86/include/asm/mshyperv.h | 3 + arch/x86/kernel/cpu/mshyperv.c | 12 ++++ 5 files changed, 105 insertions(+) create mode 100644 arch/x86/hyperv/hv_spinlock.c diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 92eb1f4..0fc8448 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -1385,6 +1385,11 @@ hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs. If specified, z/VM IUCV HVC accepts connections from listed z/VM user IDs only. + + hv_nopvspin [X86,HYPER_V] + Disables the ticketlock slowpath using HYPER-V PV + optimizations. + keep_bootcon [KNL] Do not unregister boot console at start. This is only useful for debugging when something happens in the window diff --git a/arch/x86/hyperv/Makefile b/arch/x86/hyperv/Makefile index b21ee65..1c11f94 100644 --- a/arch/x86/hyperv/Makefile +++ b/arch/x86/hyperv/Makefile @@ -1,2 +1,6 @@ obj-y := hv_init.o mmu.o nested.o obj-$(CONFIG_X86_64) += hv_apic.o + +ifdef CONFIG_X86_64 +obj-$(CONFIG_PARAVIRT_SPINLOCKS) += hv_spinlock.o +endif diff --git a/arch/x86/hyperv/hv_spinlock.c b/arch/x86/hyperv/hv_spinlock.c new file mode 100644 index 0000000..0dafcc6 --- /dev/null +++ b/arch/x86/hyperv/hv_spinlock.c @@ -0,0 +1,81 @@ +// SPDX-License-Identifier: GPL-2.0 + +/* + * Hyper-V specific spinlock code. + * + * Copyright (C) 2018, Intel, Inc. + * + * Author : Yi Sun <yi.y.sun@intel.com> + */ + +#define pr_fmt(fmt) "hv: " fmt + +#include <linux/kernel_stat.h> +#include <linux/spinlock.h> +#include <linux/debugfs.h> +#include <linux/log2.h> +#include <linux/gfp.h> + +#include <asm/mshyperv.h> +#include <asm/hyperv-tlfs.h> +#include <asm/paravirt.h> +#include <asm/qspinlock.h> +#include <asm/apic.h> + +static bool __initdata hv_pvspin = true; + +static void hv_qlock_kick(int cpu) +{ + apic->send_IPI(cpu, X86_PLATFORM_IPI_VECTOR); +} + +static void hv_qlock_wait(u8 *byte, u8 val) +{ + unsigned long msr_val; + + if (READ_ONCE(*byte) != val) + return; + + /* + * Read HV_X64_MSR_GUEST_IDLE MSR can trigger the guest's + * transition to the idle power state which can be exited + * by an IPI even if IF flag is disabled. + */ + if (ms_hyperv.features & HV_X64_MSR_GUEST_IDLE_AVAILABLE) + rdmsrl(HV_X64_MSR_GUEST_IDLE, msr_val); +} + +/* + * Hyper-V does not support this so far. + */ +bool hv_vcpu_is_preempted(int vcpu) +{ + return false; +} +PV_CALLEE_SAVE_REGS_THUNK(hv_vcpu_is_preempted); + +void __init hv_init_spinlocks(void) +{ + if (!hv_pvspin || + !apic || + !(ms_hyperv.hints & HV_X64_CLUSTER_IPI_RECOMMENDED) || + !(ms_hyperv.features & HV_X64_MSR_GUEST_IDLE_AVAILABLE)) { + pr_info("PV spinlocks disabled\n"); + return; + } + pr_info("PV spinlocks enabled\n"); + + __pv_init_lock_hash(); + pv_lock_ops.queued_spin_lock_slowpath = __pv_queued_spin_lock_slowpath; + pv_lock_ops.queued_spin_unlock = PV_CALLEE_SAVE(__pv_queued_spin_unlock); + pv_lock_ops.wait = hv_qlock_wait; + pv_lock_ops.kick = hv_qlock_kick; + pv_lock_ops.vcpu_is_preempted = PV_CALLEE_SAVE(hv_vcpu_is_preempted); +} + +static __init int hv_parse_nopvspin(char *arg) +{ + hv_pvspin = false; + return 0; +} +early_param("hv_nopvspin", hv_parse_nopvspin); diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h index f377044..ac36ea9 100644 --- a/arch/x86/include/asm/mshyperv.h +++ b/arch/x86/include/asm/mshyperv.h @@ -355,6 +355,8 @@ static inline int cpumask_to_vpset(struct hv_vpset *vpset, static inline void hv_apic_init(void) {} #endif +void __init hv_init_spinlocks(void); + #else /* CONFIG_HYPERV */ static inline void hyperv_init(void) {} static inline bool hv_is_hyperv_initialized(void) { return false; } @@ -368,6 +370,7 @@ static inline struct hv_vp_assist_page *hv_get_vp_assist_page(unsigned int cpu) return NULL; } static inline int hyperv_flush_guest_mapping(u64 as) { return -1; } +void __init hv_init_spinlocks(void) {} #endif /* CONFIG_HYPERV */ #ifdef CONFIG_HYPERV_TSCPAGE diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c index ad12733..4d12d3c 100644 --- a/arch/x86/kernel/cpu/mshyperv.c +++ b/arch/x86/kernel/cpu/mshyperv.c @@ -199,6 +199,14 @@ static unsigned long hv_get_tsc_khz(void) return freq / 1000; } +#if defined(CONFIG_SMP) && defined(CONFIG_PARAVIRT_SPINLOCKS) +static void __init hv_smp_prepare_boot_cpu(void) +{ + native_smp_prepare_boot_cpu(); + hv_init_spinlocks(); +} +#endif + static void __init ms_hyperv_init_platform(void) { int hv_host_info_eax; @@ -304,6 +312,10 @@ static void __init ms_hyperv_init_platform(void) alloc_intr_gate(HYPERV_STIMER0_VECTOR, hv_stimer0_callback_vector); #endif + +#if defined(CONFIG_SMP) && defined(CONFIG_PARAVIRT_SPINLOCKS) + smp_ops.smp_prepare_boot_cpu = hv_smp_prepare_boot_cpu; +#endif } const __initconst struct hypervisor_x86 x86_hyper_ms_hyperv = { -- 1.9.1 ^ permalink raw reply related [flat|nested] 9+ messages in thread
* RE: [PATCH v2 2/2] locking/pvqspinlock, hv: Enable PV qspinlock for Hyper-V 2018-09-21 7:25 ` [PATCH v2 2/2] locking/pvqspinlock, hv: Enable PV qspinlock for Hyper-V Yi Sun @ 2018-09-21 17:02 ` Michael Kelley (EOSG) 2018-09-25 7:11 ` Yi Sun 2018-09-21 19:09 ` kbuild test robot ` (2 subsequent siblings) 3 siblings, 1 reply; 9+ messages in thread From: Michael Kelley (EOSG) @ 2018-09-21 17:02 UTC (permalink / raw) To: Yi Sun, linux-kernel Cc: x86, tglx, chao.p.peng, chao.gao, isaku.yamahata, Tianyu Lan, KY Srinivasan, Haiyang Zhang, Stephen Hemminger From: Yi Sun <yi.y.sun@linux.intel.com> Sent: Friday, September 21, 2018 12:25 AM > + > +#define pr_fmt(fmt) "hv: " fmt Other Hyper-V messages use "Hyper-V: " as the prefix, not "hv: ". Take a quick look at 'dmesg' output for reference. > + > +#include <linux/kernel_stat.h> > +#include <linux/spinlock.h> > +#include <linux/debugfs.h> > +#include <linux/log2.h> > +#include <linux/gfp.h> Some of these #includes look like they might be leftovers from some other code. Please check and see whether kernel_stat.h, debugsfs.h, log2.h, and gfp.h are actually needed. > +static void hv_qlock_wait(u8 *byte, u8 val) > +{ > + unsigned long msr_val; > + > + if (READ_ONCE(*byte) != val) > + return; > + > + /* > + * Read HV_X64_MSR_GUEST_IDLE MSR can trigger the guest's > + * transition to the idle power state which can be exited > + * by an IPI even if IF flag is disabled. > + */ > + if (ms_hyperv.features & HV_X64_MSR_GUEST_IDLE_AVAILABLE) I can't see a case where this test is actually needed. hv_qlock_wait() can only get called if the flag is set when hv_init_spinlocks() is run, and the flag value doesn't change after it is set. > + rdmsrl(HV_X64_MSR_GUEST_IDLE, msr_val); > +} Michael ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v2 2/2] locking/pvqspinlock, hv: Enable PV qspinlock for Hyper-V 2018-09-21 17:02 ` Michael Kelley (EOSG) @ 2018-09-25 7:11 ` Yi Sun 0 siblings, 0 replies; 9+ messages in thread From: Yi Sun @ 2018-09-25 7:11 UTC (permalink / raw) To: Michael Kelley (EOSG) Cc: linux-kernel, x86, tglx, chao.p.peng, chao.gao, isaku.yamahata, Tianyu Lan, KY Srinivasan, Haiyang Zhang, Stephen Hemminger On 18-09-21 17:02:54, Michael Kelley (EOSG) wrote: > From: Yi Sun <yi.y.sun@linux.intel.com> Sent: Friday, September 21, 2018 12:25 AM > > + > > +#define pr_fmt(fmt) "hv: " fmt > > Other Hyper-V messages use "Hyper-V: " as the prefix, not "hv: ". Take > a quick look at 'dmesg' output for reference. > Will modify this. Thanks! > > + > > +#include <linux/kernel_stat.h> > > +#include <linux/spinlock.h> > > +#include <linux/debugfs.h> > > +#include <linux/log2.h> > > +#include <linux/gfp.h> > > Some of these #includes look like they might be leftovers from > some other code. Please check and see whether kernel_stat.h, > debugsfs.h, log2.h, and gfp.h are actually needed. > Sure, I will check them. > > +static void hv_qlock_wait(u8 *byte, u8 val) > > +{ > > + unsigned long msr_val; > > + > > + if (READ_ONCE(*byte) != val) > > + return; > > + > > + /* > > + * Read HV_X64_MSR_GUEST_IDLE MSR can trigger the guest's > > + * transition to the idle power state which can be exited > > + * by an IPI even if IF flag is disabled. > > + */ > > + if (ms_hyperv.features & HV_X64_MSR_GUEST_IDLE_AVAILABLE) > > I can't see a case where this test is actually needed. hv_qlock_wait() > can only get called if the flag is set when hv_init_spinlocks() is run, and > the flag value doesn't change after it is set. > Yes, it is redundant. Will remove it. > > + rdmsrl(HV_X64_MSR_GUEST_IDLE, msr_val); > > +} > > Michael ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v2 2/2] locking/pvqspinlock, hv: Enable PV qspinlock for Hyper-V 2018-09-21 7:25 ` [PATCH v2 2/2] locking/pvqspinlock, hv: Enable PV qspinlock for Hyper-V Yi Sun 2018-09-21 17:02 ` Michael Kelley (EOSG) @ 2018-09-21 19:09 ` kbuild test robot 2018-09-26 2:15 ` kbuild test robot 2018-09-26 8:23 ` Thomas Gleixner 3 siblings, 0 replies; 9+ messages in thread From: kbuild test robot @ 2018-09-21 19:09 UTC (permalink / raw) To: Yi Sun Cc: kbuild-all, linux-kernel, x86, tglx, chao.p.peng, chao.gao, isaku.yamahata, michael.h.kelley, tianyu.lan, Yi Sun, K. Y. Srinivasan, Haiyang Zhang, Stephen Hemminger [-- Attachment #1: Type: text/plain, Size: 1780 bytes --] Hi Yi, Thank you for the patch! Yet something to improve: [auto build test ERROR on tip/x86/core] [also build test ERROR on v4.19-rc4 next-20180921] [if your patch is applied to the wrong git tree, please drop us a note to help improve the system] url: https://github.com/0day-ci/linux/commits/Yi-Sun/Enable-PV-qspinlock-for-Hyper-V/20180921-234519 config: x86_64-randconfig-s1-09212334 (attached as .config) compiler: gcc-6 (Debian 6.4.0-9) 6.4.0 20171026 reproduce: # save the attached .config to linux build tree make ARCH=x86_64 All errors (new ones prefixed by >>): arch/x86/kernel/cpu/mshyperv.o: In function `hv_init_spinlocks': >> arch/x86/include/asm/mshyperv.h:373: multiple definition of `hv_init_spinlocks' arch/x86/entry/vdso/vma.o:arch/x86/include/asm/mshyperv.h:373: first defined here vim +373 arch/x86/include/asm/mshyperv.h 359 360 #else /* CONFIG_HYPERV */ 361 static inline void hyperv_init(void) {} 362 static inline bool hv_is_hyperv_initialized(void) { return false; } 363 static inline void hyperv_cleanup(void) {} 364 static inline void hyperv_setup_mmu_ops(void) {} 365 static inline void set_hv_tscchange_cb(void (*cb)(void)) {} 366 static inline void clear_hv_tscchange_cb(void) {} 367 static inline void hyperv_stop_tsc_emulation(void) {}; 368 static inline struct hv_vp_assist_page *hv_get_vp_assist_page(unsigned int cpu) 369 { 370 return NULL; 371 } 372 static inline int hyperv_flush_guest_mapping(u64 as) { return -1; } > 373 void __init hv_init_spinlocks(void) {} 374 #endif /* CONFIG_HYPERV */ 375 --- 0-DAY kernel test infrastructure Open Source Technology Center https://lists.01.org/pipermail/kbuild-all Intel Corporation [-- Attachment #2: .config.gz --] [-- Type: application/gzip, Size: 31145 bytes --] ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v2 2/2] locking/pvqspinlock, hv: Enable PV qspinlock for Hyper-V 2018-09-21 7:25 ` [PATCH v2 2/2] locking/pvqspinlock, hv: Enable PV qspinlock for Hyper-V Yi Sun 2018-09-21 17:02 ` Michael Kelley (EOSG) 2018-09-21 19:09 ` kbuild test robot @ 2018-09-26 2:15 ` kbuild test robot 2018-09-26 8:23 ` Thomas Gleixner 3 siblings, 0 replies; 9+ messages in thread From: kbuild test robot @ 2018-09-26 2:15 UTC (permalink / raw) To: Yi Sun Cc: kbuild-all, linux-kernel, x86, tglx, chao.p.peng, chao.gao, isaku.yamahata, michael.h.kelley, tianyu.lan, Yi Sun, K. Y. Srinivasan, Haiyang Zhang, Stephen Hemminger [-- Attachment #1: Type: text/plain, Size: 884 bytes --] Hi Yi, Thank you for the patch! Yet something to improve: [auto build test ERROR on tip/x86/core] [also build test ERROR on v4.19-rc5 next-20180925] [if your patch is applied to the wrong git tree, please drop us a note to help improve the system] url: https://github.com/0day-ci/linux/commits/Yi-Sun/Enable-PV-qspinlock-for-Hyper-V/20180921-234519 config: i386-allyesconfig (attached as .config) compiler: gcc-7 (Debian 7.3.0-1) 7.3.0 reproduce: # save the attached .config to linux build tree make ARCH=i386 All errors (new ones prefixed by >>): arch/x86/kernel/cpu/mshyperv.o: In function `hv_smp_prepare_boot_cpu': >> mshyperv.c:(.init.text+0x15): undefined reference to `hv_init_spinlocks' --- 0-DAY kernel test infrastructure Open Source Technology Center https://lists.01.org/pipermail/kbuild-all Intel Corporation [-- Attachment #2: .config.gz --] [-- Type: application/gzip, Size: 64465 bytes --] ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v2 2/2] locking/pvqspinlock, hv: Enable PV qspinlock for Hyper-V 2018-09-21 7:25 ` [PATCH v2 2/2] locking/pvqspinlock, hv: Enable PV qspinlock for Hyper-V Yi Sun ` (2 preceding siblings ...) 2018-09-26 2:15 ` kbuild test robot @ 2018-09-26 8:23 ` Thomas Gleixner 3 siblings, 0 replies; 9+ messages in thread From: Thomas Gleixner @ 2018-09-26 8:23 UTC (permalink / raw) To: Yi Sun Cc: linux-kernel, x86, chao.p.peng, chao.gao, isaku.yamahata, michael.h.kelley, tianyu.lan, K. Y. Srinivasan, Haiyang Zhang, Stephen Hemminger On Fri, 21 Sep 2018, Yi Sun wrote: > static inline int hyperv_flush_guest_mapping(u64 as) { return -1; } > +void __init hv_init_spinlocks(void) {} That stub want's to be static inline void hv_.... But as the code which uses it is ifdef guarded anyway, you don't need it at all. We add stub functions to avoid te ifdeffery in the code so the compiler can optimize them out, but if the ifdef guards are required for other reasons, then providing the stub for nothing is a pointless exercise. Thanks, tglx ^ permalink raw reply [flat|nested] 9+ messages in thread
end of thread, other threads:[~2018-09-26 8:23 UTC | newest] Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2018-09-21 7:25 [PATCH v2 0/2] Enable PV qspinlock for Hyper-V Yi Sun 2018-09-21 7:25 ` [PATCH v2 1/2] X86/Hyper-V: Add Guest IDLE MSR support Yi Sun 2018-09-21 16:52 ` Michael Kelley (EOSG) 2018-09-21 7:25 ` [PATCH v2 2/2] locking/pvqspinlock, hv: Enable PV qspinlock for Hyper-V Yi Sun 2018-09-21 17:02 ` Michael Kelley (EOSG) 2018-09-25 7:11 ` Yi Sun 2018-09-21 19:09 ` kbuild test robot 2018-09-26 2:15 ` kbuild test robot 2018-09-26 8:23 ` Thomas Gleixner
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