From c4ebd6295ab730bf922c96d3c4045c3a84fd1cf7 Mon Sep 17 00:00:00 2001 From: Vitaly Kuznetsov Date: Tue, 16 Oct 2018 18:50:04 +0200 Subject: [PATCH] KVM: nVMX: optimize prepare_vmcs02{,_full} for Enlightened VMCS case When Enlightened VMCS is in use by L1 hypervisor we can avoid vmwriting VMCS fields which did not change. Our first goal is to achieve minimal impact on traditional VMCS case so we're not wrapping each vmwrite() with an if-changed checker. We also can't utilize static keys as Enlightened VMCS usage is per-guest. This patch implements the simpliest solution: checking fields in groups. We skip single vmwrite() statements as doing the check will cost us something even in non-evmcs case and the win is tiny. Unfortunately, this makes prepare_vmcs02_full{,_full}() code Enlightened VMCS-dependent (and a bit ugly). Signed-off-by: Vitaly Kuznetsov Signed-off-by: Paolo Bonzini --- arch/x86/kvm/vmx.c | 116 +++++++++++++++++++++++++-------------------- 1 file changed, 64 insertions(+), 52 deletions(-) diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index cfb44acd4291..0b665c74fadc 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -12699,43 +12699,62 @@ static void prepare_vmcs02_early(struct vcpu_vmx *vmx, struct vmcs12 *vmcs12) static void prepare_vmcs02_full(struct vcpu_vmx *vmx, struct vmcs12 *vmcs12) { - vmcs_write16(GUEST_ES_SELECTOR, vmcs12->guest_es_selector); - vmcs_write16(GUEST_SS_SELECTOR, vmcs12->guest_ss_selector); - vmcs_write16(GUEST_DS_SELECTOR, vmcs12->guest_ds_selector); - vmcs_write16(GUEST_FS_SELECTOR, vmcs12->guest_fs_selector); - vmcs_write16(GUEST_GS_SELECTOR, vmcs12->guest_gs_selector); - vmcs_write16(GUEST_LDTR_SELECTOR, vmcs12->guest_ldtr_selector); - vmcs_write16(GUEST_TR_SELECTOR, vmcs12->guest_tr_selector); - vmcs_write32(GUEST_ES_LIMIT, vmcs12->guest_es_limit); - vmcs_write32(GUEST_SS_LIMIT, vmcs12->guest_ss_limit); - vmcs_write32(GUEST_DS_LIMIT, vmcs12->guest_ds_limit); - vmcs_write32(GUEST_FS_LIMIT, vmcs12->guest_fs_limit); - vmcs_write32(GUEST_GS_LIMIT, vmcs12->guest_gs_limit); - vmcs_write32(GUEST_LDTR_LIMIT, vmcs12->guest_ldtr_limit); - vmcs_write32(GUEST_TR_LIMIT, vmcs12->guest_tr_limit); - vmcs_write32(GUEST_GDTR_LIMIT, vmcs12->guest_gdtr_limit); - vmcs_write32(GUEST_IDTR_LIMIT, vmcs12->guest_idtr_limit); - vmcs_write32(GUEST_ES_AR_BYTES, vmcs12->guest_es_ar_bytes); - vmcs_write32(GUEST_SS_AR_BYTES, vmcs12->guest_ss_ar_bytes); - vmcs_write32(GUEST_DS_AR_BYTES, vmcs12->guest_ds_ar_bytes); - vmcs_write32(GUEST_FS_AR_BYTES, vmcs12->guest_fs_ar_bytes); - vmcs_write32(GUEST_GS_AR_BYTES, vmcs12->guest_gs_ar_bytes); - vmcs_write32(GUEST_LDTR_AR_BYTES, vmcs12->guest_ldtr_ar_bytes); - vmcs_write32(GUEST_TR_AR_BYTES, vmcs12->guest_tr_ar_bytes); - vmcs_writel(GUEST_SS_BASE, vmcs12->guest_ss_base); - vmcs_writel(GUEST_DS_BASE, vmcs12->guest_ds_base); - vmcs_writel(GUEST_FS_BASE, vmcs12->guest_fs_base); - vmcs_writel(GUEST_GS_BASE, vmcs12->guest_gs_base); - vmcs_writel(GUEST_LDTR_BASE, vmcs12->guest_ldtr_base); - vmcs_writel(GUEST_TR_BASE, vmcs12->guest_tr_base); - vmcs_writel(GUEST_GDTR_BASE, vmcs12->guest_gdtr_base); - vmcs_writel(GUEST_IDTR_BASE, vmcs12->guest_idtr_base); + struct hv_enlightened_vmcs *hv_evmcs = vmx->nested.hv_evmcs; - vmcs_write32(GUEST_SYSENTER_CS, vmcs12->guest_sysenter_cs); - vmcs_writel(GUEST_PENDING_DBG_EXCEPTIONS, - vmcs12->guest_pending_dbg_exceptions); - vmcs_writel(GUEST_SYSENTER_ESP, vmcs12->guest_sysenter_esp); - vmcs_writel(GUEST_SYSENTER_EIP, vmcs12->guest_sysenter_eip); + if (!hv_evmcs || !(hv_evmcs->hv_clean_fields & + HV_VMX_ENLIGHTENED_CLEAN_FIELD_GUEST_GRP2)) { + vmcs_write16(GUEST_ES_SELECTOR, vmcs12->guest_es_selector); + vmcs_write16(GUEST_SS_SELECTOR, vmcs12->guest_ss_selector); + vmcs_write16(GUEST_DS_SELECTOR, vmcs12->guest_ds_selector); + vmcs_write16(GUEST_FS_SELECTOR, vmcs12->guest_fs_selector); + vmcs_write16(GUEST_GS_SELECTOR, vmcs12->guest_gs_selector); + vmcs_write16(GUEST_LDTR_SELECTOR, vmcs12->guest_ldtr_selector); + vmcs_write16(GUEST_TR_SELECTOR, vmcs12->guest_tr_selector); + vmcs_write32(GUEST_ES_LIMIT, vmcs12->guest_es_limit); + vmcs_write32(GUEST_SS_LIMIT, vmcs12->guest_ss_limit); + vmcs_write32(GUEST_DS_LIMIT, vmcs12->guest_ds_limit); + vmcs_write32(GUEST_FS_LIMIT, vmcs12->guest_fs_limit); + vmcs_write32(GUEST_GS_LIMIT, vmcs12->guest_gs_limit); + vmcs_write32(GUEST_LDTR_LIMIT, vmcs12->guest_ldtr_limit); + vmcs_write32(GUEST_TR_LIMIT, vmcs12->guest_tr_limit); + vmcs_write32(GUEST_GDTR_LIMIT, vmcs12->guest_gdtr_limit); + vmcs_write32(GUEST_IDTR_LIMIT, vmcs12->guest_idtr_limit); + vmcs_write32(GUEST_ES_AR_BYTES, vmcs12->guest_es_ar_bytes); + vmcs_write32(GUEST_SS_AR_BYTES, vmcs12->guest_ss_ar_bytes); + vmcs_write32(GUEST_DS_AR_BYTES, vmcs12->guest_ds_ar_bytes); + vmcs_write32(GUEST_FS_AR_BYTES, vmcs12->guest_fs_ar_bytes); + vmcs_write32(GUEST_GS_AR_BYTES, vmcs12->guest_gs_ar_bytes); + vmcs_write32(GUEST_LDTR_AR_BYTES, vmcs12->guest_ldtr_ar_bytes); + vmcs_write32(GUEST_TR_AR_BYTES, vmcs12->guest_tr_ar_bytes); + vmcs_writel(GUEST_SS_BASE, vmcs12->guest_ss_base); + vmcs_writel(GUEST_DS_BASE, vmcs12->guest_ds_base); + vmcs_writel(GUEST_FS_BASE, vmcs12->guest_fs_base); + vmcs_writel(GUEST_GS_BASE, vmcs12->guest_gs_base); + vmcs_writel(GUEST_LDTR_BASE, vmcs12->guest_ldtr_base); + vmcs_writel(GUEST_TR_BASE, vmcs12->guest_tr_base); + vmcs_writel(GUEST_GDTR_BASE, vmcs12->guest_gdtr_base); + vmcs_writel(GUEST_IDTR_BASE, vmcs12->guest_idtr_base); + } + + if (!hv_evmcs || !(hv_evmcs->hv_clean_fields & + HV_VMX_ENLIGHTENED_CLEAN_FIELD_GUEST_GRP1)) { + vmcs_write32(GUEST_SYSENTER_CS, vmcs12->guest_sysenter_cs); + vmcs_writel(GUEST_PENDING_DBG_EXCEPTIONS, + vmcs12->guest_pending_dbg_exceptions); + vmcs_writel(GUEST_SYSENTER_ESP, vmcs12->guest_sysenter_esp); + vmcs_writel(GUEST_SYSENTER_EIP, vmcs12->guest_sysenter_eip); + + /* + * L1 may access the L2's PDPTR, so save them to construct + * vmcs12 + */ + if (enable_ept) { + vmcs_write64(GUEST_PDPTR0, vmcs12->guest_pdptr0); + vmcs_write64(GUEST_PDPTR1, vmcs12->guest_pdptr1); + vmcs_write64(GUEST_PDPTR2, vmcs12->guest_pdptr2); + vmcs_write64(GUEST_PDPTR3, vmcs12->guest_pdptr3); + } + } if (nested_cpu_has_xsaves(vmcs12)) vmcs_write64(XSS_EXIT_BITMAP, vmcs12->xss_exit_bitmap); @@ -12778,16 +12797,6 @@ static void prepare_vmcs02_full(struct vcpu_vmx *vmx, struct vmcs12 *vmcs12) else vmcs_write64(GUEST_BNDCFGS, vmx->nested.vmcs01_guest_bndcfgs); } - - /* - * L1 may access the L2's PDPTR, so save them to construct vmcs12 - */ - if (enable_ept) { - vmcs_write64(GUEST_PDPTR0, vmcs12->guest_pdptr0); - vmcs_write64(GUEST_PDPTR1, vmcs12->guest_pdptr1); - vmcs_write64(GUEST_PDPTR2, vmcs12->guest_pdptr2); - vmcs_write64(GUEST_PDPTR3, vmcs12->guest_pdptr3); - } } /* @@ -12805,6 +12814,7 @@ static int prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12, u32 *entry_failure_code) { struct vcpu_vmx *vmx = to_vmx(vcpu); + struct hv_enlightened_vmcs *hv_evmcs = vmx->nested.hv_evmcs; if (vmx->nested.dirty_vmcs12 || vmx->nested.hv_evmcs) { prepare_vmcs02_full(vmx, vmcs12); @@ -12815,12 +12825,14 @@ static int prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12, * First, the fields that are shadowed. This must be kept in sync * with vmx_shadow_fields.h. */ - - vmcs_write16(GUEST_CS_SELECTOR, vmcs12->guest_cs_selector); - vmcs_write32(GUEST_CS_LIMIT, vmcs12->guest_cs_limit); - vmcs_write32(GUEST_CS_AR_BYTES, vmcs12->guest_cs_ar_bytes); - vmcs_writel(GUEST_ES_BASE, vmcs12->guest_es_base); - vmcs_writel(GUEST_CS_BASE, vmcs12->guest_cs_base); + if (!hv_evmcs || !(hv_evmcs->hv_clean_fields & + HV_VMX_ENLIGHTENED_CLEAN_FIELD_GUEST_GRP2)) { + vmcs_write16(GUEST_CS_SELECTOR, vmcs12->guest_cs_selector); + vmcs_write32(GUEST_CS_LIMIT, vmcs12->guest_cs_limit); + vmcs_write32(GUEST_CS_AR_BYTES, vmcs12->guest_cs_ar_bytes); + vmcs_writel(GUEST_ES_BASE, vmcs12->guest_es_base); + vmcs_writel(GUEST_CS_BASE, vmcs12->guest_cs_base); + } if (vmx->nested.nested_run_pending && (vmcs12->vm_entry_controls & VM_ENTRY_LOAD_DEBUG_CONTROLS)) {