| Message ID | 20190830084255.55113-11-steven.price@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm64: Stolen time support | expand |
On Fri, Aug 30, 2019 at 09:42:55AM +0100, Steven Price wrote: > Enable paravirtualization features when running under a hypervisor > supporting the PV_TIME_ST hypercall. > > For each (v)CPU, we ask the hypervisor for the location of a shared > page which the hypervisor will use to report stolen time to us. We set > pv_time_ops to the stolen time function which simply reads the stolen > value from the shared page for a VCPU. We guarantee single-copy > atomicity using READ_ONCE which means we can also read the stolen > time for another VCPU than the currently running one while it is > potentially being updated by the hypervisor. > > Signed-off-by: Steven Price <steven.price@arm.com> > --- > arch/arm64/include/asm/paravirt.h | 9 +- > arch/arm64/kernel/paravirt.c | 148 ++++++++++++++++++++++++++++++ > arch/arm64/kernel/time.c | 3 + > include/linux/cpuhotplug.h | 1 + > 4 files changed, 160 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/include/asm/paravirt.h b/arch/arm64/include/asm/paravirt.h > index 799d9dd6f7cc..125c26c42902 100644 > --- a/arch/arm64/include/asm/paravirt.h > +++ b/arch/arm64/include/asm/paravirt.h > @@ -21,6 +21,13 @@ static inline u64 paravirt_steal_clock(int cpu) > { > return pv_ops.time.steal_clock(cpu); > } > -#endif > + > +int __init kvm_guest_init(void); > + > +#else > + > +#define kvm_guest_init() > + > +#endif // CONFIG_PARAVIRT > > #endif > diff --git a/arch/arm64/kernel/paravirt.c b/arch/arm64/kernel/paravirt.c > index 4cfed91fe256..5bf3be7ccf7e 100644 > --- a/arch/arm64/kernel/paravirt.c > +++ b/arch/arm64/kernel/paravirt.c > @@ -6,13 +6,161 @@ > * Author: Stefano Stabellini <stefano.stabellini@eu.citrix.com> > */ > > +#define pr_fmt(fmt) "kvmarm-pv: " fmt > + > +#include <linux/arm-smccc.h> > +#include <linux/cpuhotplug.h> > #include <linux/export.h> > +#include <linux/io.h> > #include <linux/jump_label.h> > +#include <linux/printk.h> > +#include <linux/psci.h> > +#include <linux/reboot.h> > +#include <linux/slab.h> > #include <linux/types.h> > + > #include <asm/paravirt.h> > +#include <asm/pvclock-abi.h> > +#include <asm/smp_plat.h> > > struct static_key paravirt_steal_enabled; > struct static_key paravirt_steal_rq_enabled; > > struct paravirt_patch_template pv_ops; > EXPORT_SYMBOL_GPL(pv_ops); > + > +struct kvmarm_stolen_time_region { > + struct pvclock_vcpu_stolen_time *kaddr; > +}; > + > +static DEFINE_PER_CPU(struct kvmarm_stolen_time_region, stolen_time_region); > + > +static bool steal_acc = true; > +static int __init parse_no_stealacc(char *arg) > +{ > + steal_acc = false; > + return 0; > +} > + > +early_param("no-steal-acc", parse_no_stealacc); Need to also add an 'ARM64' to the Documentation/admin-guide/kernel-parameters.txt entry for this. Thanks, drew
On 03/09/2019 09:47, Andrew Jones wrote: > On Fri, Aug 30, 2019 at 09:42:55AM +0100, Steven Price wrote: >> Enable paravirtualization features when running under a hypervisor >> supporting the PV_TIME_ST hypercall. >> >> For each (v)CPU, we ask the hypervisor for the location of a shared >> page which the hypervisor will use to report stolen time to us. We set >> pv_time_ops to the stolen time function which simply reads the stolen >> value from the shared page for a VCPU. We guarantee single-copy >> atomicity using READ_ONCE which means we can also read the stolen >> time for another VCPU than the currently running one while it is >> potentially being updated by the hypervisor. >> >> Signed-off-by: Steven Price <steven.price@arm.com> >> --- >> arch/arm64/include/asm/paravirt.h | 9 +- >> arch/arm64/kernel/paravirt.c | 148 ++++++++++++++++++++++++++++++ >> arch/arm64/kernel/time.c | 3 + >> include/linux/cpuhotplug.h | 1 + >> 4 files changed, 160 insertions(+), 1 deletion(-) >> >> diff --git a/arch/arm64/include/asm/paravirt.h b/arch/arm64/include/asm/paravirt.h >> index 799d9dd6f7cc..125c26c42902 100644 >> --- a/arch/arm64/include/asm/paravirt.h >> +++ b/arch/arm64/include/asm/paravirt.h >> @@ -21,6 +21,13 @@ static inline u64 paravirt_steal_clock(int cpu) >> { >> return pv_ops.time.steal_clock(cpu); >> } >> -#endif >> + >> +int __init kvm_guest_init(void); >> + >> +#else >> + >> +#define kvm_guest_init() >> + >> +#endif // CONFIG_PARAVIRT >> >> #endif >> diff --git a/arch/arm64/kernel/paravirt.c b/arch/arm64/kernel/paravirt.c >> index 4cfed91fe256..5bf3be7ccf7e 100644 >> --- a/arch/arm64/kernel/paravirt.c >> +++ b/arch/arm64/kernel/paravirt.c >> @@ -6,13 +6,161 @@ >> * Author: Stefano Stabellini <stefano.stabellini@eu.citrix.com> >> */ >> >> +#define pr_fmt(fmt) "kvmarm-pv: " fmt >> + >> +#include <linux/arm-smccc.h> >> +#include <linux/cpuhotplug.h> >> #include <linux/export.h> >> +#include <linux/io.h> >> #include <linux/jump_label.h> >> +#include <linux/printk.h> >> +#include <linux/psci.h> >> +#include <linux/reboot.h> >> +#include <linux/slab.h> >> #include <linux/types.h> >> + >> #include <asm/paravirt.h> >> +#include <asm/pvclock-abi.h> >> +#include <asm/smp_plat.h> >> >> struct static_key paravirt_steal_enabled; >> struct static_key paravirt_steal_rq_enabled; >> >> struct paravirt_patch_template pv_ops; >> EXPORT_SYMBOL_GPL(pv_ops); >> + >> +struct kvmarm_stolen_time_region { >> + struct pvclock_vcpu_stolen_time *kaddr; >> +}; >> + >> +static DEFINE_PER_CPU(struct kvmarm_stolen_time_region, stolen_time_region); >> + >> +static bool steal_acc = true; >> +static int __init parse_no_stealacc(char *arg) >> +{ >> + steal_acc = false; >> + return 0; >> +} >> + >> +early_param("no-steal-acc", parse_no_stealacc); > > Need to also add an 'ARM64' to the > Documentation/admin-guide/kernel-parameters.txt entry for this. Good point, thanks for the pointer. Steve
diff --git a/arch/arm64/include/asm/paravirt.h b/arch/arm64/include/asm/paravirt.h index 799d9dd6f7cc..125c26c42902 100644 --- a/arch/arm64/include/asm/paravirt.h +++ b/arch/arm64/include/asm/paravirt.h @@ -21,6 +21,13 @@ static inline u64 paravirt_steal_clock(int cpu) { return pv_ops.time.steal_clock(cpu); } -#endif + +int __init kvm_guest_init(void); + +#else + +#define kvm_guest_init() + +#endif // CONFIG_PARAVIRT #endif diff --git a/arch/arm64/kernel/paravirt.c b/arch/arm64/kernel/paravirt.c index 4cfed91fe256..5bf3be7ccf7e 100644 --- a/arch/arm64/kernel/paravirt.c +++ b/arch/arm64/kernel/paravirt.c @@ -6,13 +6,161 @@ * Author: Stefano Stabellini <stefano.stabellini@eu.citrix.com> */ +#define pr_fmt(fmt) "kvmarm-pv: " fmt + +#include <linux/arm-smccc.h> +#include <linux/cpuhotplug.h> #include <linux/export.h> +#include <linux/io.h> #include <linux/jump_label.h> +#include <linux/printk.h> +#include <linux/psci.h> +#include <linux/reboot.h> +#include <linux/slab.h> #include <linux/types.h> + #include <asm/paravirt.h> +#include <asm/pvclock-abi.h> +#include <asm/smp_plat.h> struct static_key paravirt_steal_enabled; struct static_key paravirt_steal_rq_enabled; struct paravirt_patch_template pv_ops; EXPORT_SYMBOL_GPL(pv_ops); + +struct kvmarm_stolen_time_region { + struct pvclock_vcpu_stolen_time *kaddr; +}; + +static DEFINE_PER_CPU(struct kvmarm_stolen_time_region, stolen_time_region); + +static bool steal_acc = true; +static int __init parse_no_stealacc(char *arg) +{ + steal_acc = false; + return 0; +} + +early_param("no-steal-acc", parse_no_stealacc); + +/* return stolen time in ns by asking the hypervisor */ +static u64 kvm_steal_clock(int cpu) +{ + struct kvmarm_stolen_time_region *reg; + + reg = per_cpu_ptr(&stolen_time_region, cpu); + if (!reg->kaddr) { + pr_warn_once("stolen time enabled but not configured for cpu %d\n", + cpu); + return 0; + } + + return le64_to_cpu(READ_ONCE(reg->kaddr->stolen_time)); +} + +static int disable_stolen_time_current_cpu(void) +{ + struct kvmarm_stolen_time_region *reg; + + reg = this_cpu_ptr(&stolen_time_region); + if (!reg->kaddr) + return 0; + + memunmap(reg->kaddr); + memset(reg, 0, sizeof(*reg)); + + return 0; +} + +static int stolen_time_dying_cpu(unsigned int cpu) +{ + return disable_stolen_time_current_cpu(); +} + +static int init_stolen_time_cpu(unsigned int cpu) +{ + struct kvmarm_stolen_time_region *reg; + struct arm_smccc_res res; + + reg = this_cpu_ptr(&stolen_time_region); + + arm_smccc_1_1_invoke(ARM_SMCCC_HV_PV_TIME_ST, &res); + + if ((long)res.a0 < 0) + return -EINVAL; + + reg->kaddr = memremap(res.a0, + sizeof(struct pvclock_vcpu_stolen_time), + MEMREMAP_WB); + + if (!reg->kaddr) { + pr_warn("Failed to map stolen time data structure\n"); + return -ENOMEM; + } + + if (le32_to_cpu(reg->kaddr->revision) != 0 || + le32_to_cpu(reg->kaddr->attributes) != 0) { + pr_warn("Unexpected revision or attributes in stolen time data\n"); + return -ENXIO; + } + + return 0; +} + +static int kvm_arm_init_stolen_time(void) +{ + int ret; + + ret = cpuhp_setup_state(CPUHP_AP_ARM_KVMPV_STARTING, + "hypervisor/kvmarm/pv:starting", + init_stolen_time_cpu, stolen_time_dying_cpu); + if (ret < 0) + return ret; + return 0; +} + +static bool has_kvm_steal_clock(void) +{ + struct arm_smccc_res res; + + /* To detect the presence of PV time 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_FEATURES, &res); + + if (res.a0 != SMCCC_RET_SUCCESS) + return false; + + arm_smccc_1_1_invoke(ARM_SMCCC_HV_PV_FEATURES, + ARM_SMCCC_HV_PV_TIME_ST, &res); + + if (res.a0 != SMCCC_RET_SUCCESS) + return false; + + return true; +} + +int __init kvm_guest_init(void) +{ + int ret; + + if (!has_kvm_steal_clock()) + return 0; + + ret = kvm_arm_init_stolen_time(); + if (ret) + return ret; + + pv_ops.time.steal_clock = kvm_steal_clock; + + static_key_slow_inc(¶virt_steal_enabled); + if (steal_acc) + static_key_slow_inc(¶virt_steal_rq_enabled); + + pr_info("using stolen time PV\n"); + + return 0; +} diff --git a/arch/arm64/kernel/time.c b/arch/arm64/kernel/time.c index 0b2946414dc9..a52aea14c6ec 100644 --- a/arch/arm64/kernel/time.c +++ b/arch/arm64/kernel/time.c @@ -30,6 +30,7 @@ #include <asm/thread_info.h> #include <asm/stacktrace.h> +#include <asm/paravirt.h> unsigned long profile_pc(struct pt_regs *regs) { @@ -65,4 +66,6 @@ void __init time_init(void) /* Calibrate the delay loop directly */ lpj_fine = arch_timer_rate / HZ; + + kvm_guest_init(); } diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h index 068793a619ca..89d75edb5750 100644 --- a/include/linux/cpuhotplug.h +++ b/include/linux/cpuhotplug.h @@ -136,6 +136,7 @@ enum cpuhp_state { /* Must be the last timer callback */ CPUHP_AP_DUMMY_TIMER_STARTING, CPUHP_AP_ARM_XEN_STARTING, + CPUHP_AP_ARM_KVMPV_STARTING, CPUHP_AP_ARM_CORESIGHT_STARTING, CPUHP_AP_ARM64_ISNDEP_STARTING, CPUHP_AP_SMPCFD_DYING,
Enable paravirtualization features when running under a hypervisor supporting the PV_TIME_ST hypercall. For each (v)CPU, we ask the hypervisor for the location of a shared page which the hypervisor will use to report stolen time to us. We set pv_time_ops to the stolen time function which simply reads the stolen value from the shared page for a VCPU. We guarantee single-copy atomicity using READ_ONCE which means we can also read the stolen time for another VCPU than the currently running one while it is potentially being updated by the hypervisor. Signed-off-by: Steven Price <steven.price@arm.com> --- arch/arm64/include/asm/paravirt.h | 9 +- arch/arm64/kernel/paravirt.c | 148 ++++++++++++++++++++++++++++++ arch/arm64/kernel/time.c | 3 + include/linux/cpuhotplug.h | 1 + 4 files changed, 160 insertions(+), 1 deletion(-)