On Tue, Aug 28, 2018 at 9:04 AM, Sean Christopherson
<sean.j.christopherson@xxxxxxxxx> wrote:
> Handling consistency check VMExits in nested_vmx_enter_non_root_mode()
> consolidates all relevant code into a single location, and removing
> nested_vmx_entry_failure() eliminates a confusing function name and
> label. For a VMEntry, "fail" and its derivatives has a very specific
> meaning due to the different behavior of a VMEnter VMFail versus
> VMExit, i.e. a more appropriate name for nested_vmx_entry_failure()
> would have been nested_vmx_entry_consistency_check_vmexit().
Though there is definitely some confusion regarding VMFail scenarios
versus "VM-entry failure" scenarios, "VM-entry failure" is a real
thing, and this is the terminology used in the SDM. Specifically,
Table 24-14 Format of Exit Reason describes bit 31 as "VM-entry
failure (0 = true VM exit; 1 = VM-entry failure)." I think it's better
to use the vendor's terminology than to make up terminology of our
own. These aren't "consistency check VM-exits;" they are "VM-entry
failure VM-exits."
> Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
> ---
> arch/x86/kvm/vmx.c | 90 ++++++++++++++++++++--------------------------
> 1 file changed, 39 insertions(+), 51 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 43e87a2e172e..cb8df73e9b49 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -2056,9 +2056,6 @@ static inline bool is_nmi(u32 intr_info)
> static void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason,
> u32 exit_intr_info,
> unsigned long exit_qualification);
> -static void nested_vmx_entry_failure(struct kvm_vcpu *vcpu,
> - struct vmcs12 *vmcs12,
> - u32 reason, unsigned long qualification);
>
> static int __find_msr_index(struct vcpu_vmx *vmx, u32 msr)
> {
> @@ -12546,25 +12543,23 @@ static int check_vmentry_postreqs(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12,
> return 0;
> }
>
> +static void load_vmcs12_host_state(struct kvm_vcpu *vcpu,
> + struct vmcs12 *vmcs12);
> /*
> * If exit_qual is NULL, this is being called from state restore (either RSM
> * or KVM_SET_NESTED_STATE). Otherwise it's called from vmlaunch/vmresume.
> */
> -static int nested_vmx_enter_non_root_mode(struct kvm_vcpu *vcpu, u32 *exit_qual)
> +static int nested_vmx_enter_non_root_mode(struct kvm_vcpu *vcpu,
> + bool from_vmentry)
> {
> struct vcpu_vmx *vmx = to_vmx(vcpu);
> struct vmcs12 *vmcs12 = get_vmcs12(vcpu);
> - bool from_vmentry = !!exit_qual;
> - u32 dummy_exit_qual;
> - int r;
> + u32 exit_reason = EXIT_REASON_INVALID_STATE;
> + u32 exit_qual;
>
> if (from_vmentry) {
> - r = check_vmentry_postreqs(vcpu, vmcs12, exit_qual);
> - if (r) {
> - nested_vmx_entry_failure(vcpu, vmcs12,
> - EXIT_REASON_INVALID_STATE, *exit_qual);
> - return 1;
> - }
> + if (check_vmentry_postreqs(vcpu, vmcs12, &exit_qual))
> + goto consistency_check_vmexit;
> }
>
> enter_guest_mode(vcpu);
> @@ -12578,18 +12573,17 @@ static int nested_vmx_enter_non_root_mode(struct kvm_vcpu *vcpu, u32 *exit_qual)
> if (vmcs12->cpu_based_vm_exec_control & CPU_BASED_USE_TSC_OFFSETING)
> vcpu->arch.tsc_offset += vmcs12->tsc_offset;
>
> - r = EXIT_REASON_INVALID_STATE;
> - if (prepare_vmcs02(vcpu, vmcs12, from_vmentry ? exit_qual : &dummy_exit_qual))
> + if (prepare_vmcs02(vcpu, vmcs12, &exit_qual))
> goto fail;
>
> if (from_vmentry) {
> nested_get_vmcs12_pages(vcpu);
>
> - r = EXIT_REASON_MSR_LOAD_FAIL;
> - *exit_qual = nested_vmx_load_msr(vcpu,
> - vmcs12->vm_entry_msr_load_addr,
> - vmcs12->vm_entry_msr_load_count);
> - if (*exit_qual)
> + exit_reason = EXIT_REASON_MSR_LOAD_FAIL;
> + exit_qual = nested_vmx_load_msr(vcpu,
> + vmcs12->vm_entry_msr_load_addr,
> + vmcs12->vm_entry_msr_load_count);
> + if (exit_qual)
> goto fail;
> } else {
> /*
> @@ -12615,7 +12609,28 @@ static int nested_vmx_enter_non_root_mode(struct kvm_vcpu *vcpu, u32 *exit_qual)
> vcpu->arch.tsc_offset -= vmcs12->tsc_offset;
> leave_guest_mode(vcpu);
> vmx_switch_vmcs(vcpu, &vmx->vmcs01);
> - return r;
> +
> + /*
> + * A consistency check VMExit during L1's VMEnter to L2 is a subset
> + * of a normal VMexit, as explained in 23.7 "VM-entry failures during
> + * or after loading guest state" (this also lists the acceptable exit-
> + * reason and exit-qualification parameters).
> + */
> +consistency_check_vmexit:
Obviously, I prefer vmentry_failure_vmexit, or some other label based
on the terminology used in the SDM.
> + vm_entry_controls_reset_shadow(vmx);
> + vm_exit_controls_reset_shadow(vmx);
> + vmx_segment_cache_clear(vmx);
Move to vmx_switch_vmcs.
> + if (!from_vmentry)
> + return 1;
> +
> + load_vmcs12_host_state(vcpu, vmcs12);
> + vmcs12->vm_exit_reason = exit_reason | VMX_EXIT_REASONS_FAILED_VMENTRY;
> + vmcs12->exit_qualification = exit_qual;
> + nested_vmx_succeed(vcpu);
> + if (enable_shadow_vmcs)
> + vmx->nested.sync_shadow_vmcs = true;
And does this belong in vmx_switch_vmcs as well?
