On AMD CPUs without ensuring cache consistency, each memory page reclamation in an SEV guest triggers a call to wbinvd_on_all_cpus, thereby affecting the performance of other programs on the host. Typically, an AMD server may have 128 cores or more, while the SEV guest might only utilize 8 of these cores. Meanwhile, host can use qemu-affinity to bind these 8 vCPUs to specific physical CPUs. Therefore, keeping a record of the physical core numbers each time a vCPU runs can help avoid flushing the cache for all CPUs every time. Signed-off-by: Zheyun Shen <szy0127@xxxxxxxxxxx> --- arch/x86/include/asm/smp.h | 1 + arch/x86/kvm/svm/sev.c | 28 ++++++++++++++++++++++++---- arch/x86/kvm/svm/svm.c | 4 ++++ arch/x86/kvm/svm/svm.h | 3 +++ arch/x86/lib/cache-smp.c | 7 +++++++ 5 files changed, 39 insertions(+), 4 deletions(-) diff --git a/arch/x86/include/asm/smp.h b/arch/x86/include/asm/smp.h index 4fab2ed45..19297202b 100644 --- a/arch/x86/include/asm/smp.h +++ b/arch/x86/include/asm/smp.h @@ -120,6 +120,7 @@ void native_play_dead(void); void play_dead_common(void); void wbinvd_on_cpu(int cpu); int wbinvd_on_all_cpus(void); +int wbinvd_on_cpus(struct cpumask *cpumask); void smp_kick_mwait_play_dead(void); diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index f760106c3..b6ed9a878 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -215,6 +215,21 @@ static void sev_asid_free(struct kvm_sev_info *sev) sev->misc_cg = NULL; } +struct cpumask *sev_get_cpumask(struct kvm *kvm) +{ + struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; + + return &sev->cpumask; +} + +void sev_clear_cpumask(struct kvm *kvm) +{ + struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; + + cpumask_clear(&sev->cpumask); +} + + static void sev_decommission(unsigned int handle) { struct sev_data_decommission decommission; @@ -255,6 +270,7 @@ static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp) if (unlikely(sev->active)) return ret; + cpumask_clear(&sev->cpumask); sev->active = true; sev->es_active = argp->id == KVM_SEV_ES_INIT; asid = sev_asid_new(sev); @@ -2048,7 +2064,8 @@ int sev_mem_enc_unregister_region(struct kvm *kvm, * releasing the pages back to the system for use. CLFLUSH will * not do this, so issue a WBINVD. */ - wbinvd_on_all_cpus(); + wbinvd_on_cpus(sev_get_cpumask(kvm)); + sev_clear_cpumask(kvm); __unregister_enc_region_locked(kvm, region); @@ -2152,7 +2169,8 @@ void sev_vm_destroy(struct kvm *kvm) * releasing the pages back to the system for use. CLFLUSH will * not do this, so issue a WBINVD. */ - wbinvd_on_all_cpus(); + wbinvd_on_cpus(sev_get_cpumask(kvm)); + sev_clear_cpumask(kvm); /* * if userspace was terminated before unregistering the memory regions @@ -2343,7 +2361,8 @@ static void sev_flush_encrypted_page(struct kvm_vcpu *vcpu, void *va) return; do_wbinvd: - wbinvd_on_all_cpus(); + wbinvd_on_cpus(sev_get_cpumask(vcpu->kvm)); + sev_clear_cpumask(vcpu->kvm); } void sev_guest_memory_reclaimed(struct kvm *kvm) @@ -2351,7 +2370,8 @@ void sev_guest_memory_reclaimed(struct kvm *kvm) if (!sev_guest(kvm)) return; - wbinvd_on_all_cpus(); + wbinvd_on_cpus(sev_get_cpumask(kvm)); + sev_clear_cpumask(kvm); } void sev_free_vcpu(struct kvm_vcpu *vcpu) diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index e90b429c8..f9bfa6e57 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -4107,6 +4107,10 @@ static noinstr void svm_vcpu_enter_exit(struct kvm_vcpu *vcpu, bool spec_ctrl_in amd_clear_divider(); + if (sev_guest(vcpu->kvm)) + cpumask_set_cpu(smp_processor_id(), sev_get_cpumask(vcpu->kvm)); + if (sev_es_guest(vcpu->kvm)) __svm_sev_es_vcpu_run(svm, spec_ctrl_intercepted); else diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h index 8ef95139c..1577e200e 100644 --- a/arch/x86/kvm/svm/svm.h +++ b/arch/x86/kvm/svm/svm.h @@ -90,6 +90,7 @@ struct kvm_sev_info { struct list_head mirror_entry; /* Use as a list entry of mirrors */ struct misc_cg *misc_cg; /* For misc cgroup accounting */ atomic_t migration_in_progress; + struct cpumask cpumask; /* CPU list to flush */ }; struct kvm_svm { @@ -694,6 +695,8 @@ void sev_es_vcpu_reset(struct vcpu_svm *svm); void sev_vcpu_deliver_sipi_vector(struct kvm_vcpu *vcpu, u8 vector); void sev_es_prepare_switch_to_guest(struct sev_es_save_area *hostsa); void sev_es_unmap_ghcb(struct vcpu_svm *svm); +struct cpumask *sev_get_cpumask(struct kvm *kvm); +void sev_clear_cpumask(struct kvm *kvm); /* vmenter.S */ diff --git a/arch/x86/lib/cache-smp.c b/arch/x86/lib/cache-smp.c index 7af743bd3..8806f53ba 100644 --- a/arch/x86/lib/cache-smp.c +++ b/arch/x86/lib/cache-smp.c @@ -20,3 +20,10 @@ int wbinvd_on_all_cpus(void) return 0; } EXPORT_SYMBOL(wbinvd_on_all_cpus); + +int wbinvd_on_cpus(struct cpumask *mask) +{ + on_each_cpu_cond_mask(NULL, __wbinvd, NULL, 1, mask); + return 0; +} +EXPORT_SYMBOL(wbinvd_on_cpus); -- 2.34.1