diff options
Diffstat (limited to 'arch/x86/kernel/kvm.c')
| -rw-r--r-- | arch/x86/kernel/kvm.c | 64 |
1 files changed, 61 insertions, 3 deletions
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c index e554e5ad2fe..c1d61ee4b4f 100644 --- a/arch/x86/kernel/kvm.c +++ b/arch/x86/kernel/kvm.c @@ -39,6 +39,9 @@ #include <asm/desc.h> #include <asm/tlbflush.h> #include <asm/idle.h> +#include <asm/apic.h> +#include <asm/apicdef.h> +#include <asm/hypervisor.h> static int kvmapf = 1; @@ -283,6 +286,22 @@ static void kvm_register_steal_time(void) cpu, __pa(st)); } +static DEFINE_PER_CPU(unsigned long, kvm_apic_eoi) = KVM_PV_EOI_DISABLED; + +static void kvm_guest_apic_eoi_write(u32 reg, u32 val) +{ + /** + * This relies on __test_and_clear_bit to modify the memory + * in a way that is atomic with respect to the local CPU. + * The hypervisor only accesses this memory from the local CPU so + * there's no need for lock or memory barriers. + * An optimization barrier is implied in apic write. + */ + if (__test_and_clear_bit(KVM_PV_EOI_BIT, &__get_cpu_var(kvm_apic_eoi))) + return; + apic_write(APIC_EOI, APIC_EOI_ACK); +} + void __cpuinit kvm_guest_cpu_init(void) { if (!kvm_para_available()) @@ -300,11 +319,20 @@ void __cpuinit kvm_guest_cpu_init(void) smp_processor_id()); } + if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) { + unsigned long pa; + /* Size alignment is implied but just to make it explicit. */ + BUILD_BUG_ON(__alignof__(kvm_apic_eoi) < 4); + __get_cpu_var(kvm_apic_eoi) = 0; + pa = __pa(&__get_cpu_var(kvm_apic_eoi)) | KVM_MSR_ENABLED; + wrmsrl(MSR_KVM_PV_EOI_EN, pa); + } + if (has_steal_clock) kvm_register_steal_time(); } -static void kvm_pv_disable_apf(void *unused) +static void kvm_pv_disable_apf(void) { if (!__get_cpu_var(apf_reason).enabled) return; @@ -316,11 +344,23 @@ static void kvm_pv_disable_apf(void *unused) smp_processor_id()); } +static void kvm_pv_guest_cpu_reboot(void *unused) +{ + /* + * We disable PV EOI before we load a new kernel by kexec, + * since MSR_KVM_PV_EOI_EN stores a pointer into old kernel's memory. + * New kernel can re-enable when it boots. + */ + if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) + wrmsrl(MSR_KVM_PV_EOI_EN, 0); + kvm_pv_disable_apf(); +} + static int kvm_pv_reboot_notify(struct notifier_block *nb, unsigned long code, void *unused) { if (code == SYS_RESTART) - on_each_cpu(kvm_pv_disable_apf, NULL, 1); + on_each_cpu(kvm_pv_guest_cpu_reboot, NULL, 1); return NOTIFY_DONE; } @@ -371,7 +411,9 @@ static void __cpuinit kvm_guest_cpu_online(void *dummy) static void kvm_guest_cpu_offline(void *dummy) { kvm_disable_steal_time(); - kvm_pv_disable_apf(NULL); + if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) + wrmsrl(MSR_KVM_PV_EOI_EN, 0); + kvm_pv_disable_apf(); apf_task_wake_all(); } @@ -424,6 +466,9 @@ void __init kvm_guest_init(void) pv_time_ops.steal_clock = kvm_steal_clock; } + if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) + apic_set_eoi_write(kvm_guest_apic_eoi_write); + #ifdef CONFIG_SMP smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu; register_cpu_notifier(&kvm_cpu_notifier); @@ -432,6 +477,19 @@ void __init kvm_guest_init(void) #endif } +static bool __init kvm_detect(void) +{ + if (!kvm_para_available()) + return false; + return true; +} + +const struct hypervisor_x86 x86_hyper_kvm __refconst = { + .name = "KVM", + .detect = kvm_detect, +}; +EXPORT_SYMBOL_GPL(x86_hyper_kvm); + static __init int activate_jump_labels(void) { if (has_steal_clock) { |