KVM: nVMX: generate non-true VMX MSRs based on true versions

The "non-true" VMX capability MSRs can be generated from their "true"
counterparts, by OR-ing the default1 bits. The default1 bits are fixed
and defined in the SDM.

Since we can generate the non-true VMX MSRs from the true versions,
there's no need to store both in struct nested_vmx. This also lets
userspace avoid having to restore the non-true MSRs.

Note this does not preclude emulating MSR_IA32_VMX_BASIC[55]=0. To do so,
we simply need to set all the default1 bits in the true MSRs (such that
the true MSRs and the generated non-true MSRs are equal).

Signed-off-by: David Matlack <dmatlack@google.com>
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 16a144d..9e055d8 100644 (file)
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -452,19 +452,21 @@ struct nested_vmx {
        u16 vpid02;
        u16 last_vpid;
 
+       /*
+        * We only store the "true" versions of the VMX capability MSRs. We
+        * generate the "non-true" versions by setting the must-be-1 bits
+        * according to the SDM.
+        */
        u32 nested_vmx_procbased_ctls_low;
        u32 nested_vmx_procbased_ctls_high;
-       u32 nested_vmx_true_procbased_ctls_low;
        u32 nested_vmx_secondary_ctls_low;
        u32 nested_vmx_secondary_ctls_high;
        u32 nested_vmx_pinbased_ctls_low;
        u32 nested_vmx_pinbased_ctls_high;
        u32 nested_vmx_exit_ctls_low;
        u32 nested_vmx_exit_ctls_high;
-       u32 nested_vmx_true_exit_ctls_low;
        u32 nested_vmx_entry_ctls_low;
        u32 nested_vmx_entry_ctls_high;
-       u32 nested_vmx_true_entry_ctls_low;
        u32 nested_vmx_misc_low;
        u32 nested_vmx_misc_high;
        u32 nested_vmx_ept_caps;
@@ -2740,9 +2742,7 @@ static void nested_vmx_setup_ctls_msrs(struct vcpu_vmx *vmx)
                vmx->nested.nested_vmx_exit_ctls_high |= VM_EXIT_CLEAR_BNDCFGS;
 
        /* We support free control of debug control saving. */
-       vmx->nested.nested_vmx_true_exit_ctls_low =
-               vmx->nested.nested_vmx_exit_ctls_low &
-               ~VM_EXIT_SAVE_DEBUG_CONTROLS;
+       vmx->nested.nested_vmx_exit_ctls_low &= ~VM_EXIT_SAVE_DEBUG_CONTROLS;
 
        /* entry controls */
        rdmsr(MSR_IA32_VMX_ENTRY_CTLS,
@@ -2761,9 +2761,7 @@ static void nested_vmx_setup_ctls_msrs(struct vcpu_vmx *vmx)
                vmx->nested.nested_vmx_entry_ctls_high |= VM_ENTRY_LOAD_BNDCFGS;
 
        /* We support free control of debug control loading. */
-       vmx->nested.nested_vmx_true_entry_ctls_low =
-               vmx->nested.nested_vmx_entry_ctls_low &
-               ~VM_ENTRY_LOAD_DEBUG_CONTROLS;
+       vmx->nested.nested_vmx_entry_ctls_low &= ~VM_ENTRY_LOAD_DEBUG_CONTROLS;
 
        /* cpu-based controls */
        rdmsr(MSR_IA32_VMX_PROCBASED_CTLS,
@@ -2796,8 +2794,7 @@ static void nested_vmx_setup_ctls_msrs(struct vcpu_vmx *vmx)
                CPU_BASED_USE_MSR_BITMAPS;
 
        /* We support free control of CR3 access interception. */
-       vmx->nested.nested_vmx_true_procbased_ctls_low =
-               vmx->nested.nested_vmx_procbased_ctls_low &
+       vmx->nested.nested_vmx_procbased_ctls_low &=
                ~(CPU_BASED_CR3_LOAD_EXITING | CPU_BASED_CR3_STORE_EXITING);
 
        /* secondary cpu-based controls */
@@ -2896,36 +2893,32 @@ static int vmx_get_vmx_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *pdata)
                *pdata = vmx_control_msr(
                        vmx->nested.nested_vmx_pinbased_ctls_low,
                        vmx->nested.nested_vmx_pinbased_ctls_high);
+               if (msr_index == MSR_IA32_VMX_PINBASED_CTLS)
+                       *pdata |= PIN_BASED_ALWAYSON_WITHOUT_TRUE_MSR;
                break;
        case MSR_IA32_VMX_TRUE_PROCBASED_CTLS:
-               *pdata = vmx_control_msr(
-                       vmx->nested.nested_vmx_true_procbased_ctls_low,
-                       vmx->nested.nested_vmx_procbased_ctls_high);
-               break;
        case MSR_IA32_VMX_PROCBASED_CTLS:
                *pdata = vmx_control_msr(
                        vmx->nested.nested_vmx_procbased_ctls_low,
                        vmx->nested.nested_vmx_procbased_ctls_high);
+               if (msr_index == MSR_IA32_VMX_PROCBASED_CTLS)
+                       *pdata |= CPU_BASED_ALWAYSON_WITHOUT_TRUE_MSR;
                break;
        case MSR_IA32_VMX_TRUE_EXIT_CTLS:
-               *pdata = vmx_control_msr(
-                       vmx->nested.nested_vmx_true_exit_ctls_low,
-                       vmx->nested.nested_vmx_exit_ctls_high);
-               break;
        case MSR_IA32_VMX_EXIT_CTLS:
                *pdata = vmx_control_msr(
                        vmx->nested.nested_vmx_exit_ctls_low,
                        vmx->nested.nested_vmx_exit_ctls_high);
+               if (msr_index == MSR_IA32_VMX_EXIT_CTLS)
+                       *pdata |= VM_EXIT_ALWAYSON_WITHOUT_TRUE_MSR;
                break;
        case MSR_IA32_VMX_TRUE_ENTRY_CTLS:
-               *pdata = vmx_control_msr(
-                       vmx->nested.nested_vmx_true_entry_ctls_low,
-                       vmx->nested.nested_vmx_entry_ctls_high);
-               break;
        case MSR_IA32_VMX_ENTRY_CTLS:
                *pdata = vmx_control_msr(
                        vmx->nested.nested_vmx_entry_ctls_low,
                        vmx->nested.nested_vmx_entry_ctls_high);
+               if (msr_index == MSR_IA32_VMX_ENTRY_CTLS)
+                       *pdata |= VM_ENTRY_ALWAYSON_WITHOUT_TRUE_MSR;
                break;
        case MSR_IA32_VMX_MISC:
                *pdata = vmx_control_msr(
@@ -10071,7 +10064,7 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch)
        }
 
        if (!vmx_control_verify(vmcs12->cpu_based_vm_exec_control,
-                               vmx->nested.nested_vmx_true_procbased_ctls_low,
+                               vmx->nested.nested_vmx_procbased_ctls_low,
                                vmx->nested.nested_vmx_procbased_ctls_high) ||
            !vmx_control_verify(vmcs12->secondary_vm_exec_control,
                                vmx->nested.nested_vmx_secondary_ctls_low,
@@ -10080,10 +10073,10 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch)
                                vmx->nested.nested_vmx_pinbased_ctls_low,
                                vmx->nested.nested_vmx_pinbased_ctls_high) ||
            !vmx_control_verify(vmcs12->vm_exit_controls,
-                               vmx->nested.nested_vmx_true_exit_ctls_low,
+                               vmx->nested.nested_vmx_exit_ctls_low,
                                vmx->nested.nested_vmx_exit_ctls_high) ||
            !vmx_control_verify(vmcs12->vm_entry_controls,
-                               vmx->nested.nested_vmx_true_entry_ctls_low,
+                               vmx->nested.nested_vmx_entry_ctls_low,
                                vmx->nested.nested_vmx_entry_ctls_high))
        {
                nested_vmx_failValid(vcpu, VMXERR_ENTRY_INVALID_CONTROL_FIELD);