diff options
Diffstat (limited to 'arch/x86/kvm/vmx/nested.c')
| -rw-r--r-- | arch/x86/kvm/vmx/nested.c | 100 |
1 files changed, 48 insertions, 52 deletions
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index 6957bb6f5cf7..ddf6df7bee93 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -336,6 +336,7 @@ static void nested_put_vmcs12_pages(struct kvm_vcpu *vcpu) static void free_nested(struct kvm_vcpu *vcpu) { struct vcpu_vmx *vmx = to_vmx(vcpu); + struct vmcs *shadow_vmcs; if (WARN_ON_ONCE(vmx->loaded_vmcs != &vmx->vmcs01)) vmx_switch_vmcs(vcpu, &vmx->vmcs01); @@ -353,9 +354,15 @@ static void free_nested(struct kvm_vcpu *vcpu) vmx->nested.current_vmptr = INVALID_GPA; if (enable_shadow_vmcs) { vmx_disable_shadow_vmcs(vmx); - vmcs_clear(vmx->vmcs01.shadow_vmcs); - free_vmcs(vmx->vmcs01.shadow_vmcs); + + /* + * Keep the pointer visible until after VMCLEAR, so migration + * can clear an active shadow VMCS on the old CPU. + */ + shadow_vmcs = vmx->vmcs01.shadow_vmcs; + vmcs_clear(shadow_vmcs); vmx->vmcs01.shadow_vmcs = NULL; + free_vmcs(shadow_vmcs); } kfree(vmx->nested.cached_vmcs12); vmx->nested.cached_vmcs12 = NULL; @@ -582,6 +589,9 @@ static int nested_vmx_check_msr_bitmap_controls(struct kvm_vcpu *vcpu, static int nested_vmx_check_tpr_shadow_controls(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12) { + gpa_t vtpr_gpa = vmcs12->virtual_apic_page_addr + APIC_TASKPRI; + u32 vtpr; + if (!nested_cpu_has(vmcs12, CPU_BASED_TPR_SHADOW)) return 0; @@ -591,6 +601,32 @@ static int nested_vmx_check_tpr_shadow_controls(struct kvm_vcpu *vcpu, if (CC(!nested_cpu_has_vid(vmcs12) && vmcs12->tpr_threshold >> 4)) return -EINVAL; + /* + * Do the illegal vTPR vs. TPR Threshold consistency check if and only + * if KVM is configured to WARN on missed consistency checks, otherwise + * it's a waste of time. KVM needs to rely on hardware to fully detect + * an illegal combination due to the vTPR being writable by L1 at all + * times (it's an in-memory value, not a VMCS field). I.e. even if the + * check passes now, it might fail at the actual VM-Enter. + * + * If reading guest memory fails, skip the check as KVM's de facto ABI + * for VMX instruction accesses to non-existent memory is to provide + * PCI Bus Error semantics (reads return 0xFFs), in which case the vTPR + * is guaranteed to greater than or equal to the threshold. + * + * Note! Deliberately use the VM-scoped API when reading guest memory, + * to ensure the read doesn't hit SMRAM when restoring L2 state on RSM, + * and only perform the check when in KVM_RUN, to avoid a false failure + * if userspace hasn't yet configured memslots during state restore. + */ + if (warn_on_missed_cc && vcpu->wants_to_run && + nested_cpu_has(vmcs12, CPU_BASED_TPR_SHADOW) && + !nested_cpu_has_vid(vmcs12) && + !nested_cpu_has2(vmcs12, SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES) && + !kvm_read_guest(vcpu->kvm, vtpr_gpa, &vtpr, sizeof(vtpr)) && + CC((vmcs12->tpr_threshold & GENMASK(3, 0)) > ((vtpr >> 4) & GENMASK(3, 0)))) + return -EINVAL; + return 0; } @@ -3104,38 +3140,6 @@ static int nested_vmx_check_controls(struct kvm_vcpu *vcpu, return 0; } -static int nested_vmx_check_controls_late(struct kvm_vcpu *vcpu, - struct vmcs12 *vmcs12) -{ - void *vapic = to_vmx(vcpu)->nested.virtual_apic_map.hva; - u32 vtpr = vapic ? (*(u32 *)(vapic + APIC_TASKPRI)) >> 4 : 0; - - /* - * Don't bother with the consistency checks if KVM isn't configured to - * WARN on missed consistency checks, as KVM needs to rely on hardware - * to fully detect an illegal vTPR vs. TRP Threshold combination due to - * the vTPR being writable by L1 at all times (it's an in-memory value, - * not a VMCS field). I.e. even if the check passes now, it might fail - * at the actual VM-Enter. - * - * Keying off the module param also allows treating an invalid vAPIC - * mapping as a consistency check failure without increasing the risk - * of breaking a "real" VM. - */ - if (!warn_on_missed_cc) - return 0; - - if ((exec_controls_get(to_vmx(vcpu)) & CPU_BASED_TPR_SHADOW) && - nested_cpu_has(vmcs12, CPU_BASED_TPR_SHADOW) && - !nested_cpu_has_vid(vmcs12) && - !nested_cpu_has2(vmcs12, SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES) && - (CC(!vapic) || - CC((vmcs12->tpr_threshold & GENMASK(3, 0)) > (vtpr & GENMASK(3, 0))))) - return -EINVAL; - - return 0; -} - static int nested_vmx_check_address_space_size(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12) { @@ -3661,19 +3665,14 @@ enum nvmx_vmentry_status nested_vmx_enter_non_root_mode(struct kvm_vcpu *vcpu, &vmx->nested.pre_vmenter_ssp_tbl); /* - * Overwrite vmcs01.GUEST_CR3 with L1's CR3 if EPT is disabled. In the - * event of a "late" VM-Fail, i.e. a VM-Fail detected by hardware but - * not KVM, KVM must unwind its software model to the pre-VM-Entry host - * state. When EPT is disabled, GUEST_CR3 holds KVM's shadow CR3, not - * L1's "real" CR3, which causes nested_vmx_restore_host_state() to - * corrupt vcpu->arch.cr3. Stuffing vmcs01.GUEST_CR3 results in the - * unwind naturally setting arch.cr3 to the correct value. Smashing - * vmcs01.GUEST_CR3 is safe because nested VM-Exits, and the unwind, - * reset KVM's MMU, i.e. vmcs01.GUEST_CR3 is guaranteed to be - * overwritten with a shadow CR3 prior to re-entering L1. + * Stash L1's CR3, so that in the event of a "late" VM-Fail, i.e. a + * VM-Fail detected by hardware but not KVM, KVM can unwind its + * software model to the pre-VM-Entry host state. When EPT is + * disabled, GUEST_CR3 holds KVM's shadow CR3, not L1's "real" CR3, + * and so simply restoring from vmcs01.GUEST_CR3 would corrupt + * vcpu->arch.cr3. */ - if (!enable_ept) - vmcs_writel(GUEST_CR3, vcpu->arch.cr3); + vmx->nested.pre_vmenter_cr3 = kvm_read_cr3(vcpu); vmx_switch_vmcs(vcpu, &vmx->nested.vmcs02); @@ -3685,11 +3684,6 @@ enum nvmx_vmentry_status nested_vmx_enter_non_root_mode(struct kvm_vcpu *vcpu, return NVMX_VMENTRY_KVM_INTERNAL_ERROR; } - if (nested_vmx_check_controls_late(vcpu, vmcs12)) { - vmx_switch_vmcs(vcpu, &vmx->vmcs01); - return NVMX_VMENTRY_VMFAIL; - } - if (nested_vmx_check_guest_state(vcpu, vmcs12, &entry_failure_code)) { exit_reason.basic = EXIT_REASON_INVALID_STATE; @@ -3774,6 +3768,8 @@ vmentry_fail_vmexit: if (!from_vmentry) return NVMX_VMENTRY_VMEXIT; + nested_put_vmcs12_pages(vcpu); + load_vmcs12_host_state(vcpu, vmcs12); vmcs12->vm_exit_reason = exit_reason.full; if (enable_shadow_vmcs || nested_vmx_is_evmptr12_valid(vmx)) @@ -4990,7 +4986,7 @@ static void nested_vmx_restore_host_state(struct kvm_vcpu *vcpu) vmx_set_cr4(vcpu, vmcs_readl(CR4_READ_SHADOW)); nested_ept_uninit_mmu_context(vcpu); - vcpu->arch.cr3 = vmcs_readl(GUEST_CR3); + vcpu->arch.cr3 = vmx->nested.pre_vmenter_cr3; kvm_register_mark_available(vcpu, VCPU_REG_CR3); /* |