diff options
| author | David Woodhouse <dwmw@amazon.co.uk> | 2021-02-02 15:48:05 +0000 |
|---|---|---|
| committer | David Woodhouse <dwmw@amazon.co.uk> | 2021-02-04 14:19:38 +0000 |
| commit | 7d6bbebb7bb0294ede7bda04847272854e34f87c (patch) | |
| tree | f406d06318ceeb0e6dffa26c415f0100b69eb9c5 /arch/x86/kvm | |
| parent | 78e9878cb376969d184a4b7fff392528fe17a3ce (diff) | |
| download | linux-7d6bbebb7bb0294ede7bda04847272854e34f87c.tar.bz2 | |
KVM: x86/xen: Add kvm_xen_enabled static key
The code paths for Xen support are all fairly lightweight but if we hide
them behind this, they're even *more* lightweight for any system which
isn't actually hosting Xen guests.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Diffstat (limited to 'arch/x86/kvm')
| -rw-r--r-- | arch/x86/kvm/x86.c | 2 | ||||
| -rw-r--r-- | arch/x86/kvm/xen.c | 17 | ||||
| -rw-r--r-- | arch/x86/kvm/xen.h | 10 |
3 files changed, 27 insertions, 2 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 673dcc6fde7e..ffc4ab3bd6ec 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -7988,6 +7988,7 @@ void kvm_arch_exit(void) kvm_mmu_module_exit(); free_percpu(user_return_msrs); kmem_cache_destroy(x86_fpu_cache); + WARN_ON(static_branch_unlikely(&kvm_xen_enabled.key)); } static int __kvm_vcpu_halt(struct kvm_vcpu *vcpu, int state, int reason) @@ -10581,6 +10582,7 @@ void kvm_arch_destroy_vm(struct kvm *kvm) kfree(srcu_dereference_check(kvm->arch.pmu_event_filter, &kvm->srcu, 1)); kvm_mmu_uninit_vm(kvm); kvm_page_track_cleanup(kvm); + kvm_xen_destroy_vm(kvm); kvm_hv_destroy_vm(kvm); } diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c index b52549fc6dbc..7d03d918e595 100644 --- a/arch/x86/kvm/xen.c +++ b/arch/x86/kvm/xen.c @@ -16,6 +16,8 @@ #include "trace.h" +DEFINE_STATIC_KEY_DEFERRED_FALSE(kvm_xen_enabled, HZ); + int kvm_xen_write_hypercall_page(struct kvm_vcpu *vcpu, u64 data) { struct kvm *kvm = vcpu->kvm; @@ -93,10 +95,25 @@ int kvm_xen_hvm_config(struct kvm *kvm, struct kvm_xen_hvm_config *xhc) xhc->blob_size_32 || xhc->blob_size_64)) return -EINVAL; + mutex_lock(&kvm->lock); + + if (xhc->msr && !kvm->arch.xen_hvm_config.msr) + static_branch_inc(&kvm_xen_enabled.key); + else if (!xhc->msr && kvm->arch.xen_hvm_config.msr) + static_branch_slow_dec_deferred(&kvm_xen_enabled); + memcpy(&kvm->arch.xen_hvm_config, xhc, sizeof(*xhc)); + + mutex_unlock(&kvm->lock); return 0; } +void kvm_xen_destroy_vm(struct kvm *kvm) +{ + if (kvm->arch.xen_hvm_config.msr) + static_branch_slow_dec_deferred(&kvm_xen_enabled); +} + static int kvm_xen_hypercall_set_result(struct kvm_vcpu *vcpu, u64 result) { kvm_rax_write(vcpu, result); diff --git a/arch/x86/kvm/xen.h b/arch/x86/kvm/xen.h index 28e9c9892628..ec3d8f6d0ef5 100644 --- a/arch/x86/kvm/xen.h +++ b/arch/x86/kvm/xen.h @@ -9,14 +9,20 @@ #ifndef __ARCH_X86_KVM_XEN_H__ #define __ARCH_X86_KVM_XEN_H__ +#include <linux/jump_label_ratelimit.h> + +extern struct static_key_false_deferred kvm_xen_enabled; + int kvm_xen_hypercall(struct kvm_vcpu *vcpu); int kvm_xen_write_hypercall_page(struct kvm_vcpu *vcpu, u64 data); int kvm_xen_hvm_config(struct kvm *kvm, struct kvm_xen_hvm_config *xhc); +void kvm_xen_destroy_vm(struct kvm *kvm); static inline bool kvm_xen_hypercall_enabled(struct kvm *kvm) { - return kvm->arch.xen_hvm_config.flags & - KVM_XEN_HVM_CONFIG_INTERCEPT_HCALL; + return static_branch_unlikely(&kvm_xen_enabled.key) && + (kvm->arch.xen_hvm_config.flags & + KVM_XEN_HVM_CONFIG_INTERCEPT_HCALL); } #endif /* __ARCH_X86_KVM_XEN_H__ */ |