>From e9a4f9af27d7d384dc36ad66a9856f9decb8ce02 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Tue, 8 Nov 2022 15:32:58 -0800 Subject: [PATCH 2/2] KVM: SVM: Snapshot host save area PA in dedicated per-CPU variable Track the SME-aware physical address of the host save area outside of "struct svm_cpu_data" so that a future patch can easily reference the address from assembly code. The "overhead" of always allocating the per-CPU data is more or less meaningless in the grand scheme. And when KVM AMD is built as a module, it's actually more costly (by a single pointer) to dynamically allocate the struct, as the per-CPU data is allocated only when the module is loaded. Signed-off-by: Sean Christopherson --- arch/x86/kvm/svm/svm.c | 30 ++++++++++++++++-------------- arch/x86/kvm/svm/svm.h | 2 +- 2 files changed, 17 insertions(+), 15 deletions(-) diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index bb7427fd1242..8fc02bef4f85 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -246,6 +246,7 @@ struct kvm_ldttss_desc { } __attribute__((packed)); DEFINE_PER_CPU(struct svm_cpu_data *, svm_data); +DEFINE_PER_CPU(unsigned long, svm_host_save_area_pa); /* * Only MSR_TSC_AUX is switched via the user return hook. EFER is switched via @@ -597,7 +598,7 @@ static int svm_hardware_enable(void) wrmsrl(MSR_EFER, efer | EFER_SVME); - wrmsrl(MSR_VM_HSAVE_PA, __sme_page_pa(sd->save_area)); + wrmsrl(MSR_VM_HSAVE_PA, per_cpu(svm_host_save_area_pa, me)); if (static_cpu_has(X86_FEATURE_TSCRATEMSR)) { /* @@ -653,12 +654,13 @@ static void svm_cpu_uninit(int cpu) per_cpu(svm_data, cpu) = NULL; kfree(sd->sev_vmcbs); - __free_page(sd->save_area); + __free_page(__sme_pa_to_page(per_cpu(svm_host_save_area_pa, cpu))); kfree(sd); } static int svm_cpu_init(int cpu) { + struct page *host_save_area; struct svm_cpu_data *sd; int ret = -ENOMEM; @@ -666,20 +668,20 @@ static int svm_cpu_init(int cpu) if (!sd) return ret; sd->cpu = cpu; - sd->save_area = alloc_page(GFP_KERNEL | __GFP_ZERO); - if (!sd->save_area) - goto free_cpu_data; ret = sev_cpu_init(sd); if (ret) - goto free_save_area; + goto free_cpu_data; + + host_save_area = alloc_page(GFP_KERNEL | __GFP_ZERO); + if (!host_save_area) + goto free_cpu_data; per_cpu(svm_data, cpu) = sd; + per_cpu(svm_host_save_area_pa, cpu) = __sme_page_pa(host_save_area); return 0; -free_save_area: - __free_page(sd->save_area); free_cpu_data: kfree(sd); return ret; @@ -1449,7 +1451,6 @@ static void svm_vcpu_free(struct kvm_vcpu *vcpu) static void svm_prepare_switch_to_guest(struct kvm_vcpu *vcpu) { struct vcpu_svm *svm = to_svm(vcpu); - struct svm_cpu_data *sd = per_cpu(svm_data, vcpu->cpu); if (sev_es_guest(vcpu->kvm)) sev_es_unmap_ghcb(svm); @@ -1461,10 +1462,13 @@ static void svm_prepare_switch_to_guest(struct kvm_vcpu *vcpu) * Save additional host state that will be restored on VMEXIT (sev-es) * or subsequent vmload of host save area. */ - vmsave(__sme_page_pa(sd->save_area)); + vmsave(per_cpu(svm_host_save_area_pa, vcpu->cpu)); if (sev_es_guest(vcpu->kvm)) { struct sev_es_save_area *hostsa; - hostsa = (struct sev_es_save_area *)(page_address(sd->save_area) + 0x400); + struct page *hostsa_page; + + hostsa_page = __sme_pa_to_page(per_cpu(svm_host_save_area_pa, vcpu->cpu)); + hostsa = (struct sev_es_save_area *)(page_address(hostsa_page) + 0x400); sev_es_prepare_switch_to_guest(hostsa); } @@ -3920,8 +3924,6 @@ static noinstr void svm_vcpu_enter_exit(struct kvm_vcpu *vcpu) if (sev_es_guest(vcpu->kvm)) { __svm_sev_es_vcpu_run(vmcb_pa); } else { - struct svm_cpu_data *sd = per_cpu(svm_data, vcpu->cpu); - /* * Use a single vmcb (vmcb01 because it's always valid) for * context switching guest state via VMLOAD/VMSAVE, that way @@ -3932,7 +3934,7 @@ static noinstr void svm_vcpu_enter_exit(struct kvm_vcpu *vcpu) __svm_vcpu_run(vmcb_pa, (unsigned long *)&vcpu->arch.regs); vmsave(svm->vmcb01.pa); - vmload(__sme_page_pa(sd->save_area)); + vmload(per_cpu(svm_host_save_area_pa, vcpu->cpu)); } guest_state_exit_irqoff(); diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h index 9a2567803006..d9ec8ea69a56 100644 --- a/arch/x86/kvm/svm/svm.h +++ b/arch/x86/kvm/svm/svm.h @@ -303,7 +303,6 @@ struct svm_cpu_data { u32 min_asid; struct kvm_ldttss_desc *tss_desc; - struct page *save_area; struct vmcb *current_vmcb; /* index = sev_asid, value = vmcb pointer */ @@ -311,6 +310,7 @@ struct svm_cpu_data { }; DECLARE_PER_CPU(struct svm_cpu_data *, svm_data); +DECLARE_PER_CPU(unsigned long, svm_host_save_area_pa); void recalc_intercepts(struct vcpu_svm *svm); -- 2.38.1.431.g37b22c650d-goog