Add two hypercalls to KVM hypervisor to support pv-ticketlocks. KVM_HC_WAIT_FOR_KICK blocks the calling vcpu until another vcpu kicks it or it is woken up because of an event like interrupt.
KVM_HC_KICK_CPU allows the calling vcpu to kick another vcpu. The presence of these hypercalls is indicated to guest via KVM_FEATURE_WAIT_FOR_KICK/KVM_CAP_WAIT_FOR_KICK. Qemu needs a corresponding patch to pass up the presence of this feature to guest via cpuid. Patch to qemu will be sent separately. Signed-off-by: Srivatsa Vaddagiri <va...@linux.vnet.ibm.com> Signed-off-by: Suzuki Poulose <suz...@in.ibm.com> --- arch/x86/include/asm/kvm_para.h | 2 + arch/x86/kvm/x86.c | 69 +++++++++++++++++++++++++++++++++++++++- include/linux/kvm.h | 1 include/linux/kvm_host.h | 1 include/linux/kvm_para.h | 2 + virt/kvm/kvm_main.c | 1 6 files changed, 75 insertions(+), 1 deletion(-) Index: linux-2.6.37/arch/x86/include/asm/kvm_para.h =================================================================== --- linux-2.6.37.orig/arch/x86/include/asm/kvm_para.h +++ linux-2.6.37/arch/x86/include/asm/kvm_para.h @@ -16,6 +16,8 @@ #define KVM_FEATURE_CLOCKSOURCE 0 #define KVM_FEATURE_NOP_IO_DELAY 1 #define KVM_FEATURE_MMU_OP 2 +#define KVM_FEATURE_WAIT_FOR_KICK 4 + /* This indicates that the new set of kvmclock msrs * are available. The use of 0x11 and 0x12 is deprecated */ Index: linux-2.6.37/arch/x86/kvm/x86.c =================================================================== --- linux-2.6.37.orig/arch/x86/kvm/x86.c +++ linux-2.6.37/arch/x86/kvm/x86.c @@ -1922,6 +1922,7 @@ int kvm_dev_ioctl_check_extension(long e case KVM_CAP_DEBUGREGS: case KVM_CAP_X86_ROBUST_SINGLESTEP: case KVM_CAP_XSAVE: + case KVM_CAP_WAIT_FOR_KICK: r = 1; break; case KVM_CAP_COALESCED_MMIO: @@ -2340,7 +2341,8 @@ static void do_cpuid_ent(struct kvm_cpui entry->eax = (1 << KVM_FEATURE_CLOCKSOURCE) | (1 << KVM_FEATURE_NOP_IO_DELAY) | (1 << KVM_FEATURE_CLOCKSOURCE2) | - (1 << KVM_FEATURE_CLOCKSOURCE_STABLE_BIT); + (1 << KVM_FEATURE_CLOCKSOURCE_STABLE_BIT) | + (1 << KVM_FEATURE_WAIT_FOR_KICK); entry->ebx = 0; entry->ecx = 0; entry->edx = 0; @@ -4766,6 +4768,63 @@ int kvm_hv_hypercall(struct kvm_vcpu *vc return 1; } +/* + * kvm_pv_wait_for_kick_op : Block until kicked by either a KVM_HC_KICK_CPU + * hypercall or a event like interrupt. + * + * @vcpu : vcpu which is blocking. + */ +static void kvm_pv_wait_for_kick_op(struct kvm_vcpu *vcpu) +{ + DEFINE_WAIT(wait); + + /* + * Blocking on vcpu->wq allows us to wake up sooner if required to + * service pending events (like interrupts). + * + * Also set state to TASK_INTERRUPTIBLE before checking vcpu->kicked to + * avoid racing with kvm_pv_kick_cpu_op(). + */ + prepare_to_wait(&vcpu->wq, &wait, TASK_INTERRUPTIBLE); + + do { + /* + * Somebody has already tried kicking us. Acknowledge that + * and terminate the wait. + */ + if (vcpu->kicked) { + vcpu->kicked = 0; + break; + } + + /* Let's wait for either KVM_HC_KICK_CPU or someother event + * to wake us up. + */ + + srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx); + schedule(); + vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu); + + } while (0); + + finish_wait(&vcpu->wq, &wait); +} + +/* + * kvm_pv_kick_cpu_op: Kick a vcpu. + * + * @cpu - vcpu to be kicked. + */ +static void kvm_pv_kick_cpu_op(struct kvm *kvm, int cpu) +{ + struct kvm_vcpu *vcpu = kvm_get_vcpu(kvm, cpu); + + if (vcpu) { + vcpu->kicked = 1; + wake_up_interruptible(&vcpu->wq); + } +} + int kvm_emulate_hypercall(struct kvm_vcpu *vcpu) { unsigned long nr, a0, a1, a2, a3, ret; @@ -4802,6 +4861,14 @@ int kvm_emulate_hypercall(struct kvm_vcp case KVM_HC_MMU_OP: r = kvm_pv_mmu_op(vcpu, a0, hc_gpa(vcpu, a1, a2), &ret); break; + case KVM_HC_WAIT_FOR_KICK: + kvm_pv_wait_for_kick_op(vcpu); + ret = 0; + break; + case KVM_HC_KICK_CPU: + kvm_pv_kick_cpu_op(vcpu->kvm, a0); + ret = 0; + break; default: ret = -KVM_ENOSYS; break; Index: linux-2.6.37/include/linux/kvm.h =================================================================== --- linux-2.6.37.orig/include/linux/kvm.h +++ linux-2.6.37/include/linux/kvm.h @@ -540,6 +540,7 @@ struct kvm_ppc_pvinfo { #endif #define KVM_CAP_PPC_GET_PVINFO 57 #define KVM_CAP_PPC_IRQ_LEVEL 58 +#define KVM_CAP_WAIT_FOR_KICK 59 #ifdef KVM_CAP_IRQ_ROUTING Index: linux-2.6.37/include/linux/kvm_host.h =================================================================== --- linux-2.6.37.orig/include/linux/kvm_host.h +++ linux-2.6.37/include/linux/kvm_host.h @@ -105,6 +105,7 @@ struct kvm_vcpu { #endif struct kvm_vcpu_arch arch; + int kicked; }; /* Index: linux-2.6.37/include/linux/kvm_para.h =================================================================== --- linux-2.6.37.orig/include/linux/kvm_para.h +++ linux-2.6.37/include/linux/kvm_para.h @@ -19,6 +19,8 @@ #define KVM_HC_MMU_OP 2 #define KVM_HC_FEATURES 3 #define KVM_HC_PPC_MAP_MAGIC_PAGE 4 +#define KVM_HC_WAIT_FOR_KICK 5 +#define KVM_HC_KICK_CPU 6 /* * hypercalls use architecture specific Index: linux-2.6.37/virt/kvm/kvm_main.c =================================================================== --- linux-2.6.37.orig/virt/kvm/kvm_main.c +++ linux-2.6.37/virt/kvm/kvm_main.c @@ -185,6 +185,7 @@ int kvm_vcpu_init(struct kvm_vcpu *vcpu, vcpu->cpu = -1; vcpu->kvm = kvm; vcpu->vcpu_id = id; + vcpu->kicked = 0; init_waitqueue_head(&vcpu->wq); page = alloc_page(GFP_KERNEL | __GFP_ZERO); _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linux-foundation.org/mailman/listinfo/virtualization