diff options
Diffstat (limited to 'arch/x86/kvm/vmx/nested.c')
| -rw-r--r-- | arch/x86/kvm/vmx/nested.c | 47 |
1 files changed, 25 insertions, 22 deletions
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index e58caff92694..f4b1ae439763 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -514,31 +514,11 @@ static inline bool nested_vmx_prepare_msr_bitmap(struct kvm_vcpu *vcpu, unsigned long *msr_bitmap_l0 = to_vmx(vcpu)->nested.vmcs02.msr_bitmap; struct kvm_host_map *map = &to_vmx(vcpu)->nested.msr_bitmap_map; - /* - * pred_cmd & spec_ctrl are trying to verify two things: - * - * 1. L0 gave a permission to L1 to actually passthrough the MSR. This - * ensures that we do not accidentally generate an L02 MSR bitmap - * from the L12 MSR bitmap that is too permissive. - * 2. That L1 or L2s have actually used the MSR. This avoids - * unnecessarily merging of the bitmap if the MSR is unused. This - * works properly because we only update the L01 MSR bitmap lazily. - * So even if L0 should pass L1 these MSRs, the L01 bitmap is only - * updated to reflect this when L1 (or its L2s) actually write to - * the MSR. - */ - bool pred_cmd = !msr_write_intercepted_l01(vcpu, MSR_IA32_PRED_CMD); - bool spec_ctrl = !msr_write_intercepted_l01(vcpu, MSR_IA32_SPEC_CTRL); - /* Nothing to do if the MSR bitmap is not in use. */ if (!cpu_has_vmx_msr_bitmap() || !nested_cpu_has(vmcs12, CPU_BASED_USE_MSR_BITMAPS)) return false; - if (!nested_cpu_has_virt_x2apic_mode(vmcs12) && - !pred_cmd && !spec_ctrl) - return false; - if (kvm_vcpu_map(vcpu, gpa_to_gfn(vmcs12->msr_bitmap), map)) return false; @@ -583,13 +563,36 @@ static inline bool nested_vmx_prepare_msr_bitmap(struct kvm_vcpu *vcpu, } } - if (spec_ctrl) + /* KVM unconditionally exposes the FS/GS base MSRs to L1. */ + nested_vmx_disable_intercept_for_msr(msr_bitmap_l1, msr_bitmap_l0, + MSR_FS_BASE, MSR_TYPE_RW); + + nested_vmx_disable_intercept_for_msr(msr_bitmap_l1, msr_bitmap_l0, + MSR_GS_BASE, MSR_TYPE_RW); + + nested_vmx_disable_intercept_for_msr(msr_bitmap_l1, msr_bitmap_l0, + MSR_KERNEL_GS_BASE, MSR_TYPE_RW); + + /* + * Checking the L0->L1 bitmap is trying to verify two things: + * + * 1. L0 gave a permission to L1 to actually passthrough the MSR. This + * ensures that we do not accidentally generate an L02 MSR bitmap + * from the L12 MSR bitmap that is too permissive. + * 2. That L1 or L2s have actually used the MSR. This avoids + * unnecessarily merging of the bitmap if the MSR is unused. This + * works properly because we only update the L01 MSR bitmap lazily. + * So even if L0 should pass L1 these MSRs, the L01 bitmap is only + * updated to reflect this when L1 (or its L2s) actually write to + * the MSR. + */ + if (!msr_write_intercepted_l01(vcpu, MSR_IA32_SPEC_CTRL)) nested_vmx_disable_intercept_for_msr( msr_bitmap_l1, msr_bitmap_l0, MSR_IA32_SPEC_CTRL, MSR_TYPE_R | MSR_TYPE_W); - if (pred_cmd) + if (!msr_write_intercepted_l01(vcpu, MSR_IA32_PRED_CMD)) nested_vmx_disable_intercept_for_msr( msr_bitmap_l1, msr_bitmap_l0, MSR_IA32_PRED_CMD, |