| Message ID | 20191217135549.3240-6-yezengruan@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: arm64: vcpu preempted check support | expand |
On Tue, Dec 17, 2019 at 01:55:49PM +0000, yezengruan@huawei.com wrote: > From: Zengruan Ye <yezengruan@huawei.com> > > Support the vcpu_is_preempted() functionality under KVM/arm64. This will > enhance lock performance on overcommitted hosts (more runnable vcpus > than physical cpus in the system) as doing busy waits for preempted > vcpus will hurt system performance far worse than early yielding. > > unix benchmark result: > host: kernel 5.5.0-rc1, HiSilicon Kunpeng920, 8 cpus > guest: kernel 5.5.0-rc1, 16 vcpus > > test-case | after-patch | before-patch > ----------------------------------------+-------------------+------------------ > Dhrystone 2 using register variables | 334600751.0 lps | 335319028.3 lps > Double-Precision Whetstone | 32856.1 MWIPS | 32849.6 MWIPS > Execl Throughput | 3662.1 lps | 2718.0 lps > File Copy 1024 bufsize 2000 maxblocks | 432906.4 KBps | 158011.8 KBps > File Copy 256 bufsize 500 maxblocks | 116023.0 KBps | 37664.0 KBps > File Copy 4096 bufsize 8000 maxblocks | 1432769.8 KBps | 441108.8 KBps > Pipe Throughput | 6405029.6 lps | 6021457.6 lps > Pipe-based Context Switching | 185872.7 lps | 184255.3 lps > Process Creation | 4025.7 lps | 3706.6 lps > Shell Scripts (1 concurrent) | 6745.6 lpm | 6436.1 lpm > Shell Scripts (8 concurrent) | 998.7 lpm | 931.1 lpm > System Call Overhead | 3913363.1 lps | 3883287.8 lps > ----------------------------------------+-------------------+------------------ > System Benchmarks Index Score | 1835.1 | 1327.6 > > Signed-off-by: Zengruan Ye <yezengruan@huawei.com> > --- > arch/arm64/include/asm/paravirt.h | 3 + > arch/arm64/kernel/paravirt.c | 91 +++++++++++++++++++++++++++++++ > arch/arm64/kernel/setup.c | 2 + > include/linux/cpuhotplug.h | 1 + > 4 files changed, 97 insertions(+) > > diff --git a/arch/arm64/include/asm/paravirt.h b/arch/arm64/include/asm/paravirt.h > index 7b1c81b544bb..a2cd0183bbef 100644 > --- a/arch/arm64/include/asm/paravirt.h > +++ b/arch/arm64/include/asm/paravirt.h > @@ -29,6 +29,8 @@ static inline u64 paravirt_steal_clock(int cpu) > > int __init pv_time_init(void); > > +int __init kvm_guest_init(void); > + This is a *very* generic name - I suggest something like pv_lock_init() so it's clear what the function actually does. > __visible bool __native_vcpu_is_preempted(int cpu); > > static inline bool pv_vcpu_is_preempted(int cpu) > @@ -39,6 +41,7 @@ static inline bool pv_vcpu_is_preempted(int cpu) > #else > > #define pv_time_init() do {} while (0) > +#define kvm_guest_init() do {} while (0) > > #endif // CONFIG_PARAVIRT > > diff --git a/arch/arm64/kernel/paravirt.c b/arch/arm64/kernel/paravirt.c > index d8f1ba8c22ce..a86dead40473 100644 > --- a/arch/arm64/kernel/paravirt.c > +++ b/arch/arm64/kernel/paravirt.c > @@ -22,6 +22,7 @@ > #include <asm/paravirt.h> > #include <asm/pvclock-abi.h> > #include <asm/smp_plat.h> > +#include <asm/pvlock-abi.h> > > struct static_key paravirt_steal_enabled; > struct static_key paravirt_steal_rq_enabled; > @@ -158,3 +159,93 @@ int __init pv_time_init(void) > > return 0; > } > + > +DEFINE_PER_CPU(struct pvlock_vcpu_state, pvlock_vcpu_region) __aligned(64); > +EXPORT_PER_CPU_SYMBOL(pvlock_vcpu_region); > + > +static int pvlock_vcpu_state_dying_cpu(unsigned int cpu) > +{ > + struct pvlock_vcpu_state *reg; > + > + reg = this_cpu_ptr(&pvlock_vcpu_region); > + if (!reg) > + return -EFAULT; > + > + memset(reg, 0, sizeof(*reg)); I might be missing something obvious here - but I don't see the point of this. The hypervisor might immediately overwrite the structure again. Indeed you should conside a mechanism for the guest to "unregister" the region - otherwise you will face issues with the likes of kexec. For pv_time the memory is allocated by the hypervisor not the guest to avoid lifetime issues about kexec. > + > + return 0; > +} > + > +static int init_pvlock_vcpu_state(unsigned int cpu) > +{ > + struct pvlock_vcpu_state *reg; > + struct arm_smccc_res res; > + > + reg = this_cpu_ptr(&pvlock_vcpu_region); > + if (!reg) > + return -EFAULT; > + > + /* Pass the memory address to host via hypercall */ > + arm_smccc_1_1_invoke(ARM_SMCCC_HV_PV_LOCK_PREEMPTED, > + virt_to_phys(reg), &res); > + > + return 0; > +} > + > +static bool kvm_vcpu_is_preempted(int cpu) > +{ > + struct pvlock_vcpu_state *reg = &per_cpu(pvlock_vcpu_region, cpu); > + > + if (reg) > + return !!(reg->preempted & 1); > + > + return false; > +} > + > +static int kvm_arm_init_pvlock(void) > +{ > + int ret; > + > + ret = cpuhp_setup_state(CPUHP_AP_ARM_KVM_PVLOCK_STARTING, > + "hypervisor/arm/pvlock:starting", > + init_pvlock_vcpu_state, > + pvlock_vcpu_state_dying_cpu); > + if (ret < 0) > + return ret; > + > + pv_ops.lock.vcpu_is_preempted = kvm_vcpu_is_preempted; > + > + pr_info("using PV-lock preempted\n"); > + > + return 0; > +} > + > +static bool has_kvm_pvlock(void) > +{ > + struct arm_smccc_res res; > + > + /* To detect the presence of PV lock support we require SMCCC 1.1+ */ > + if (psci_ops.smccc_version < SMCCC_VERSION_1_1) > + return false; > + > + arm_smccc_1_1_invoke(ARM_SMCCC_ARCH_FEATURES_FUNC_ID, > + ARM_SMCCC_HV_PV_LOCK_FEATURES, &res); > + > + if (res.a0 != SMCCC_RET_SUCCESS) > + return false; > + > + return true; > +} > + > +int __init kvm_guest_init(void) > +{ > + if (is_hyp_mode_available()) > + return 0; > + > + if (!has_kvm_pvlock()) > + return 0; > + > + kvm_arm_init_pvlock(); Consider reporting errors from kvm_arm_init_pvlock()? At the moment it's impossible to tell the difference between pvlock not being supported and something failing in the setup. Steve > + > + return 0; > +} > diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c > index 56f664561754..64c4d515ba2d 100644 > --- a/arch/arm64/kernel/setup.c > +++ b/arch/arm64/kernel/setup.c > @@ -341,6 +341,8 @@ void __init setup_arch(char **cmdline_p) > smp_init_cpus(); > smp_build_mpidr_hash(); > > + kvm_guest_init(); > + > /* Init percpu seeds for random tags after cpus are set up. */ > kasan_init_tags(); > > diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h > index e51ee772b9f5..f72ff95ab63a 100644 > --- a/include/linux/cpuhotplug.h > +++ b/include/linux/cpuhotplug.h > @@ -138,6 +138,7 @@ enum cpuhp_state { > CPUHP_AP_DUMMY_TIMER_STARTING, > CPUHP_AP_ARM_XEN_STARTING, > CPUHP_AP_ARM_KVMPV_STARTING, > + CPUHP_AP_ARM_KVM_PVLOCK_STARTING, > CPUHP_AP_ARM_CORESIGHT_STARTING, > CPUHP_AP_ARM64_ISNDEP_STARTING, > CPUHP_AP_SMPCFD_DYING, > -- > 2.19.1 > >
Hi Steve, On 2019/12/17 22:40, Steven Price wrote: > On Tue, Dec 17, 2019 at 01:55:49PM +0000, yezengruan@huawei.com wrote: >> From: Zengruan Ye <yezengruan@huawei.com> >> >> Support the vcpu_is_preempted() functionality under KVM/arm64. This will >> enhance lock performance on overcommitted hosts (more runnable vcpus >> than physical cpus in the system) as doing busy waits for preempted >> vcpus will hurt system performance far worse than early yielding. >> >> unix benchmark result: >> host: kernel 5.5.0-rc1, HiSilicon Kunpeng920, 8 cpus >> guest: kernel 5.5.0-rc1, 16 vcpus >> >> test-case | after-patch | before-patch >> ----------------------------------------+-------------------+------------------ >> Dhrystone 2 using register variables | 334600751.0 lps | 335319028.3 lps >> Double-Precision Whetstone | 32856.1 MWIPS | 32849.6 MWIPS >> Execl Throughput | 3662.1 lps | 2718.0 lps >> File Copy 1024 bufsize 2000 maxblocks | 432906.4 KBps | 158011.8 KBps >> File Copy 256 bufsize 500 maxblocks | 116023.0 KBps | 37664.0 KBps >> File Copy 4096 bufsize 8000 maxblocks | 1432769.8 KBps | 441108.8 KBps >> Pipe Throughput | 6405029.6 lps | 6021457.6 lps >> Pipe-based Context Switching | 185872.7 lps | 184255.3 lps >> Process Creation | 4025.7 lps | 3706.6 lps >> Shell Scripts (1 concurrent) | 6745.6 lpm | 6436.1 lpm >> Shell Scripts (8 concurrent) | 998.7 lpm | 931.1 lpm >> System Call Overhead | 3913363.1 lps | 3883287.8 lps >> ----------------------------------------+-------------------+------------------ >> System Benchmarks Index Score | 1835.1 | 1327.6 >> >> Signed-off-by: Zengruan Ye <yezengruan@huawei.com> >> --- >> arch/arm64/include/asm/paravirt.h | 3 + >> arch/arm64/kernel/paravirt.c | 91 +++++++++++++++++++++++++++++++ >> arch/arm64/kernel/setup.c | 2 + >> include/linux/cpuhotplug.h | 1 + >> 4 files changed, 97 insertions(+) >> >> diff --git a/arch/arm64/include/asm/paravirt.h b/arch/arm64/include/asm/paravirt.h >> index 7b1c81b544bb..a2cd0183bbef 100644 >> --- a/arch/arm64/include/asm/paravirt.h >> +++ b/arch/arm64/include/asm/paravirt.h >> @@ -29,6 +29,8 @@ static inline u64 paravirt_steal_clock(int cpu) >> >> int __init pv_time_init(void); >> >> +int __init kvm_guest_init(void); >> + > > This is a *very* generic name - I suggest something like pv_lock_init() > so it's clear what the function actually does. > >> __visible bool __native_vcpu_is_preempted(int cpu); >> >> static inline bool pv_vcpu_is_preempted(int cpu) >> @@ -39,6 +41,7 @@ static inline bool pv_vcpu_is_preempted(int cpu) >> #else >> >> #define pv_time_init() do {} while (0) >> +#define kvm_guest_init() do {} while (0) >> >> #endif // CONFIG_PARAVIRT >> >> diff --git a/arch/arm64/kernel/paravirt.c b/arch/arm64/kernel/paravirt.c >> index d8f1ba8c22ce..a86dead40473 100644 >> --- a/arch/arm64/kernel/paravirt.c >> +++ b/arch/arm64/kernel/paravirt.c >> @@ -22,6 +22,7 @@ >> #include <asm/paravirt.h> >> #include <asm/pvclock-abi.h> >> #include <asm/smp_plat.h> >> +#include <asm/pvlock-abi.h> >> >> struct static_key paravirt_steal_enabled; >> struct static_key paravirt_steal_rq_enabled; >> @@ -158,3 +159,93 @@ int __init pv_time_init(void) >> >> return 0; >> } >> + >> +DEFINE_PER_CPU(struct pvlock_vcpu_state, pvlock_vcpu_region) __aligned(64); >> +EXPORT_PER_CPU_SYMBOL(pvlock_vcpu_region); >> + >> +static int pvlock_vcpu_state_dying_cpu(unsigned int cpu) >> +{ >> + struct pvlock_vcpu_state *reg; >> + >> + reg = this_cpu_ptr(&pvlock_vcpu_region); >> + if (!reg) >> + return -EFAULT; >> + >> + memset(reg, 0, sizeof(*reg)); > > I might be missing something obvious here - but I don't see the point of > this. The hypervisor might immediately overwrite the structure again. > Indeed you should conside a mechanism for the guest to "unregister" the > region - otherwise you will face issues with the likes of kexec. > > For pv_time the memory is allocated by the hypervisor not the guest to > avoid lifetime issues about kexec. Thanks for pointing it out to me! I'll update the memory allocation mechanism of the PV lock structure to avoid lifetime issues about kexec. > >> + >> + return 0; >> +} >> + >> +static int init_pvlock_vcpu_state(unsigned int cpu) >> +{ >> + struct pvlock_vcpu_state *reg; >> + struct arm_smccc_res res; >> + >> + reg = this_cpu_ptr(&pvlock_vcpu_region); >> + if (!reg) >> + return -EFAULT; >> + >> + /* Pass the memory address to host via hypercall */ >> + arm_smccc_1_1_invoke(ARM_SMCCC_HV_PV_LOCK_PREEMPTED, >> + virt_to_phys(reg), &res); >> + >> + return 0; >> +} >> + >> +static bool kvm_vcpu_is_preempted(int cpu) >> +{ >> + struct pvlock_vcpu_state *reg = &per_cpu(pvlock_vcpu_region, cpu); >> + >> + if (reg) >> + return !!(reg->preempted & 1); >> + >> + return false; >> +} >> + >> +static int kvm_arm_init_pvlock(void) >> +{ >> + int ret; >> + >> + ret = cpuhp_setup_state(CPUHP_AP_ARM_KVM_PVLOCK_STARTING, >> + "hypervisor/arm/pvlock:starting", >> + init_pvlock_vcpu_state, >> + pvlock_vcpu_state_dying_cpu); >> + if (ret < 0) >> + return ret; >> + >> + pv_ops.lock.vcpu_is_preempted = kvm_vcpu_is_preempted; >> + >> + pr_info("using PV-lock preempted\n"); >> + >> + return 0; >> +} >> + >> +static bool has_kvm_pvlock(void) >> +{ >> + struct arm_smccc_res res; >> + >> + /* To detect the presence of PV lock support we require SMCCC 1.1+ */ >> + if (psci_ops.smccc_version < SMCCC_VERSION_1_1) >> + return false; >> + >> + arm_smccc_1_1_invoke(ARM_SMCCC_ARCH_FEATURES_FUNC_ID, >> + ARM_SMCCC_HV_PV_LOCK_FEATURES, &res); >> + >> + if (res.a0 != SMCCC_RET_SUCCESS) >> + return false; >> + >> + return true; >> +} >> + >> +int __init kvm_guest_init(void) >> +{ >> + if (is_hyp_mode_available()) >> + return 0; >> + >> + if (!has_kvm_pvlock()) >> + return 0; >> + >> + kvm_arm_init_pvlock(); > > Consider reporting errors from kvm_arm_init_pvlock()? At the moment > it's impossible to tell the difference between pvlock not being > supported and something failing in the setup. Good point, I'll update the code. > > Steve > >> + >> + return 0; >> +} >> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c >> index 56f664561754..64c4d515ba2d 100644 >> --- a/arch/arm64/kernel/setup.c >> +++ b/arch/arm64/kernel/setup.c >> @@ -341,6 +341,8 @@ void __init setup_arch(char **cmdline_p) >> smp_init_cpus(); >> smp_build_mpidr_hash(); >> >> + kvm_guest_init(); >> + >> /* Init percpu seeds for random tags after cpus are set up. */ >> kasan_init_tags(); >> >> diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h >> index e51ee772b9f5..f72ff95ab63a 100644 >> --- a/include/linux/cpuhotplug.h >> +++ b/include/linux/cpuhotplug.h >> @@ -138,6 +138,7 @@ enum cpuhp_state { >> CPUHP_AP_DUMMY_TIMER_STARTING, >> CPUHP_AP_ARM_XEN_STARTING, >> CPUHP_AP_ARM_KVMPV_STARTING, >> + CPUHP_AP_ARM_KVM_PVLOCK_STARTING, >> CPUHP_AP_ARM_CORESIGHT_STARTING, >> CPUHP_AP_ARM64_ISNDEP_STARTING, >> CPUHP_AP_SMPCFD_DYING, >> -- >> 2.19.1 >> >> > > . > Thanks, Zengruan
diff --git a/arch/arm64/include/asm/paravirt.h b/arch/arm64/include/asm/paravirt.h index 7b1c81b544bb..a2cd0183bbef 100644 --- a/arch/arm64/include/asm/paravirt.h +++ b/arch/arm64/include/asm/paravirt.h @@ -29,6 +29,8 @@ static inline u64 paravirt_steal_clock(int cpu) int __init pv_time_init(void); +int __init kvm_guest_init(void); + __visible bool __native_vcpu_is_preempted(int cpu); static inline bool pv_vcpu_is_preempted(int cpu) @@ -39,6 +41,7 @@ static inline bool pv_vcpu_is_preempted(int cpu) #else #define pv_time_init() do {} while (0) +#define kvm_guest_init() do {} while (0) #endif // CONFIG_PARAVIRT diff --git a/arch/arm64/kernel/paravirt.c b/arch/arm64/kernel/paravirt.c index d8f1ba8c22ce..a86dead40473 100644 --- a/arch/arm64/kernel/paravirt.c +++ b/arch/arm64/kernel/paravirt.c @@ -22,6 +22,7 @@ #include <asm/paravirt.h> #include <asm/pvclock-abi.h> #include <asm/smp_plat.h> +#include <asm/pvlock-abi.h> struct static_key paravirt_steal_enabled; struct static_key paravirt_steal_rq_enabled; @@ -158,3 +159,93 @@ int __init pv_time_init(void) return 0; } + +DEFINE_PER_CPU(struct pvlock_vcpu_state, pvlock_vcpu_region) __aligned(64); +EXPORT_PER_CPU_SYMBOL(pvlock_vcpu_region); + +static int pvlock_vcpu_state_dying_cpu(unsigned int cpu) +{ + struct pvlock_vcpu_state *reg; + + reg = this_cpu_ptr(&pvlock_vcpu_region); + if (!reg) + return -EFAULT; + + memset(reg, 0, sizeof(*reg)); + + return 0; +} + +static int init_pvlock_vcpu_state(unsigned int cpu) +{ + struct pvlock_vcpu_state *reg; + struct arm_smccc_res res; + + reg = this_cpu_ptr(&pvlock_vcpu_region); + if (!reg) + return -EFAULT; + + /* Pass the memory address to host via hypercall */ + arm_smccc_1_1_invoke(ARM_SMCCC_HV_PV_LOCK_PREEMPTED, + virt_to_phys(reg), &res); + + return 0; +} + +static bool kvm_vcpu_is_preempted(int cpu) +{ + struct pvlock_vcpu_state *reg = &per_cpu(pvlock_vcpu_region, cpu); + + if (reg) + return !!(reg->preempted & 1); + + return false; +} + +static int kvm_arm_init_pvlock(void) +{ + int ret; + + ret = cpuhp_setup_state(CPUHP_AP_ARM_KVM_PVLOCK_STARTING, + "hypervisor/arm/pvlock:starting", + init_pvlock_vcpu_state, + pvlock_vcpu_state_dying_cpu); + if (ret < 0) + return ret; + + pv_ops.lock.vcpu_is_preempted = kvm_vcpu_is_preempted; + + pr_info("using PV-lock preempted\n"); + + return 0; +} + +static bool has_kvm_pvlock(void) +{ + struct arm_smccc_res res; + + /* To detect the presence of PV lock support we require SMCCC 1.1+ */ + if (psci_ops.smccc_version < SMCCC_VERSION_1_1) + return false; + + arm_smccc_1_1_invoke(ARM_SMCCC_ARCH_FEATURES_FUNC_ID, + ARM_SMCCC_HV_PV_LOCK_FEATURES, &res); + + if (res.a0 != SMCCC_RET_SUCCESS) + return false; + + return true; +} + +int __init kvm_guest_init(void) +{ + if (is_hyp_mode_available()) + return 0; + + if (!has_kvm_pvlock()) + return 0; + + kvm_arm_init_pvlock(); + + return 0; +} diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c index 56f664561754..64c4d515ba2d 100644 --- a/arch/arm64/kernel/setup.c +++ b/arch/arm64/kernel/setup.c @@ -341,6 +341,8 @@ void __init setup_arch(char **cmdline_p) smp_init_cpus(); smp_build_mpidr_hash(); + kvm_guest_init(); + /* Init percpu seeds for random tags after cpus are set up. */ kasan_init_tags(); diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h index e51ee772b9f5..f72ff95ab63a 100644 --- a/include/linux/cpuhotplug.h +++ b/include/linux/cpuhotplug.h @@ -138,6 +138,7 @@ enum cpuhp_state { CPUHP_AP_DUMMY_TIMER_STARTING, CPUHP_AP_ARM_XEN_STARTING, CPUHP_AP_ARM_KVMPV_STARTING, + CPUHP_AP_ARM_KVM_PVLOCK_STARTING, CPUHP_AP_ARM_CORESIGHT_STARTING, CPUHP_AP_ARM64_ISNDEP_STARTING, CPUHP_AP_SMPCFD_DYING,