The patch adds guest code for msr between guest and hypervisor. The msr will export the vcpu running/pre-empted information to the guest from host. This will enable guest to intelligently send ipi to running vcpus and set flag for pre-empted vcpus. This will prevent waiting for vcpus that are not running.
Suggested-by: Peter Zijlstra <[email protected]> Signed-off-by: Nikunj A. Dadhania <[email protected]> --- arch/x86/include/asm/kvm_para.h | 10 ++++++++++ arch/x86/kernel/kvm.c | 33 +++++++++++++++++++++++++++++++++ 2 files changed, 43 insertions(+), 0 deletions(-) diff --git a/arch/x86/include/asm/kvm_para.h b/arch/x86/include/asm/kvm_para.h index 77266d3..f57b5cc 100644 --- a/arch/x86/include/asm/kvm_para.h +++ b/arch/x86/include/asm/kvm_para.h @@ -24,6 +24,7 @@ #define KVM_FEATURE_ASYNC_PF 4 #define KVM_FEATURE_STEAL_TIME 5 #define KVM_FEATURE_PV_UNHALT 6 +#define KVM_FEATURE_VCPU_STATE 7 /* The last 8 bits are used to indicate how to interpret the flags field * in pvclock structure. If no bits are set, all flags are ignored. @@ -39,6 +40,7 @@ #define MSR_KVM_SYSTEM_TIME_NEW 0x4b564d01 #define MSR_KVM_ASYNC_PF_EN 0x4b564d02 #define MSR_KVM_STEAL_TIME 0x4b564d03 +#define MSR_KVM_VCPU_STATE 0x4b564d04 struct kvm_steal_time { __u64 steal; @@ -51,6 +53,14 @@ struct kvm_steal_time { #define KVM_STEAL_VALID_BITS ((-1ULL << (KVM_STEAL_ALIGNMENT_BITS + 1))) #define KVM_STEAL_RESERVED_MASK (((1 << KVM_STEAL_ALIGNMENT_BITS) - 1 ) << 1) +struct kvm_vcpu_state { + __u32 state; + __u32 pad[15]; +}; + +#define KVM_VCPU_STATE_ALIGN_BITS 5 +#define KVM_VCPU_STATE_VALID_BITS ((-1ULL << (KVM_VCPU_STATE_ALIGN_BITS + 1))) + #define KVM_MAX_MMU_OP_BATCH 32 #define KVM_ASYNC_PF_ENABLED (1 << 0) diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c index 98f0378..bb686a6 100644 --- a/arch/x86/kernel/kvm.c +++ b/arch/x86/kernel/kvm.c @@ -64,6 +64,9 @@ static DEFINE_PER_CPU(struct kvm_vcpu_pv_apf_data, apf_reason) __aligned(64); static DEFINE_PER_CPU(struct kvm_steal_time, steal_time) __aligned(64); static int has_steal_clock = 0; +DEFINE_PER_CPU(struct kvm_vcpu_state, vcpu_state) __aligned(64); +static int has_vcpu_state; + /* * No need for any "IO delay" on KVM */ @@ -291,6 +294,22 @@ static void kvm_register_steal_time(void) cpu, __pa(st)); } +static void kvm_register_vcpu_state(void) +{ + int cpu = smp_processor_id(); + struct kvm_vcpu_state *v_state; + + if (!has_vcpu_state) + return; + + v_state = &per_cpu(vcpu_state, cpu); + memset(v_state, 0, sizeof(*v_state)); + + wrmsrl(MSR_KVM_VCPU_STATE, (__pa(v_state) | KVM_MSR_ENABLED)); + printk(KERN_INFO "kvm-vcpustate: cpu %d, msr %lu\n", + cpu, __pa(v_state)); +} + void __cpuinit kvm_guest_cpu_init(void) { if (!kvm_para_available()) @@ -310,6 +329,9 @@ void __cpuinit kvm_guest_cpu_init(void) if (has_steal_clock) kvm_register_steal_time(); + + if (has_vcpu_state) + kvm_register_vcpu_state(); } static void kvm_pv_disable_apf(void *unused) @@ -361,6 +383,14 @@ void kvm_disable_steal_time(void) wrmsr(MSR_KVM_STEAL_TIME, 0, 0); } +void kvm_disable_vcpu_state(void) +{ + if (!has_vcpu_state) + return; + + wrmsr(MSR_KVM_VCPU_STATE, 0, 0); +} + #ifdef CONFIG_SMP static void __init kvm_smp_prepare_boot_cpu(void) { @@ -379,6 +409,7 @@ static void __cpuinit kvm_guest_cpu_online(void *dummy) static void kvm_guest_cpu_offline(void *dummy) { + kvm_disable_vcpu_state(); kvm_disable_steal_time(); kvm_pv_disable_apf(NULL); apf_task_wake_all(); @@ -433,6 +464,8 @@ void __init kvm_guest_init(void) pv_time_ops.steal_clock = kvm_steal_clock; } + has_vcpu_state = 1; + #ifdef CONFIG_SMP smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu; register_cpu_notifier(&kvm_cpu_notifier); -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
