[PATCH v6 5/7] KVM: nVMX: Set VM-{Fail,Exit} failure info via params, not return val

Sean Christopherson
2019-04-11T19:18:15Z

Convert all top-level nested VM-Enter consistency check functions to
use explicit parameters to pass failure information to the caller.
Using an explicit parameter achieves several goals:

- Provides consistent prototypes for all functions.
- Self-documents the net effect of failure, e.g. without the explicit
parameter it may not be obvious that nested_vmx_check_guest_state()
leads to a VM-Exit.
- Does not give the false impression that failure information is
always consumed and/or relevant, e.g. vmx_set_nested_state() only
cares whether or not the checks were successful.

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
arch/x86/kvm/vmx/nested.c | 61 ++++++++++++++++++++++-----------------
1 file changed, 35 insertions(+), 26 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index b22605d5ee9e..16cff40456ee 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -817,7 +817,8 @@ static int nested_vmx_store_msr_check(struct kvm_vcpu *vcpu,
* Load guest's/host's msr at nested entry/exit.
* return 0 for success, entry index for failure.
*/
-static u32 nested_vmx_load_msr(struct kvm_vcpu *vcpu, u64 gpa, u32 count)
+static int nested_vmx_load_msr(struct kvm_vcpu *vcpu, u64 gpa, u32 count,
+ u32 *exit_reason, u32 *exit_qual)
{
u32 i;
struct vmx_msr_entry e;
@@ -849,7 +850,9 @@ static u32 nested_vmx_load_msr(struct kvm_vcpu *vcpu, u64 gpa, u32 count)
}
return 0;
fail:
- return i + 1;
+ *exit_reason = EXIT_REASON_MSR_LOAD_FAIL;
+ *exit_qual = i + 1;
+ return -EINVAL;
}

static int nested_vmx_store_msr(struct kvm_vcpu *vcpu, u64 gpa, u32 count)
@@ -2574,12 +2577,15 @@ static int nested_check_vm_entry_controls(struct kvm_vcpu *vcpu,
}

static int nested_vmx_check_controls(struct kvm_vcpu *vcpu,
- struct vmcs12 *vmcs12)
+ struct vmcs12 *vmcs12,
+ u32 *vm_instruction_error)
{
+ *vm_instruction_error = VMXERR_ENTRY_INVALID_CONTROL_FIELD;
+
if (nested_check_vm_execution_controls(vcpu, vmcs12) ||
nested_check_vm_exit_controls(vcpu, vmcs12) ||
nested_check_vm_entry_controls(vcpu, vmcs12))
- return VMXERR_ENTRY_INVALID_CONTROL_FIELD;
+ return -EINVAL;

return 0;
}
@@ -2624,10 +2630,13 @@ static int nested_check_host_control_regs(struct kvm_vcpu *vcpu,
}

static int nested_vmx_check_host_state(struct kvm_vcpu *vcpu,
- struct vmcs12 *vmcs12)
+ struct vmcs12 *vmcs12,
+ u32 *vm_instruction_error)
{
+ *vm_instruction_error = VMXERR_ENTRY_INVALID_HOST_STATE_FIELD;
+
if (nested_check_host_control_regs(vcpu, vmcs12))
- return VMXERR_ENTRY_INVALID_HOST_STATE_FIELD;
+ return -EINVAL;

return 0;
}
@@ -2673,10 +2682,12 @@ static int nested_check_guest_non_reg_state(struct vmcs12 *vmcs12)

static int nested_vmx_check_guest_state(struct kvm_vcpu *vcpu,
struct vmcs12 *vmcs12,
+ u32 *exit_reason,
u32 *exit_qual)
{
bool ia32e;

+ *exit_reason = EXIT_REASON_INVALID_STATE;
*exit_qual = ENTRY_FAIL_DEFAULT;

if (!nested_guest_cr0_valid(vcpu, vmcs12->guest_cr0) ||
@@ -2965,7 +2976,7 @@ 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 evaluate_pending_interrupts;
- u32 exit_reason = EXIT_REASON_INVALID_STATE;
+ u32 exit_reason;
u32 exit_qual;

evaluate_pending_interrupts = vmcs_read32(CPU_BASED_VM_EXEC_CONTROL) &
@@ -2991,7 +3002,8 @@ int nested_vmx_enter_non_root_mode(struct kvm_vcpu *vcpu, bool from_vmentry)
return -1;
}

- if (nested_vmx_check_guest_state(vcpu, vmcs12, &exit_qual))
+ if (nested_vmx_check_guest_state(vcpu, vmcs12,
+ &exit_reason, &exit_qual))
goto vmentry_fail_vmexit;
}

@@ -3003,11 +3015,9 @@ int nested_vmx_enter_non_root_mode(struct kvm_vcpu *vcpu, bool from_vmentry)
goto vmentry_fail_vmexit_guest_mode;

if (from_vmentry) {
- 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)
+ if (nested_vmx_load_msr(vcpu, vmcs12->vm_entry_msr_load_addr,
+ vmcs12->vm_entry_msr_load_count,
+ &exit_reason, &exit_qual))
goto vmentry_fail_vmexit_guest_mode;
} else {
/*
@@ -3087,6 +3097,7 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch)
struct vmcs12 *vmcs12;
struct vcpu_vmx *vmx = to_vmx(vcpu);
u32 interrupt_shadow = vmx_get_interrupt_shadow(vcpu);
+ u32 vm_instruction_error;
int ret;

if (!nested_vmx_check_permission(vcpu))
@@ -3136,13 +3147,11 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch)
launch ? VMXERR_VMLAUNCH_NONCLEAR_VMCS
: VMXERR_VMRESUME_NONLAUNCHED_VMCS);

- ret = nested_vmx_check_controls(vcpu, vmcs12);
- if (ret)
- return nested_vmx_failValid(vcpu, ret);
+ if (nested_vmx_check_controls(vcpu, vmcs12, &vm_instruction_error))
+ return nested_vmx_failValid(vcpu, vm_instruction_error);

- ret = nested_vmx_check_host_state(vcpu, vmcs12);
- if (ret)
- return nested_vmx_failValid(vcpu, ret);
+ if (nested_vmx_check_host_state(vcpu, vmcs12, &vm_instruction_error))
+ return nested_vmx_failValid(vcpu, vm_instruction_error);

/*
* We're finally done with prerequisite checking, and can start with
@@ -3594,7 +3603,7 @@ static void load_vmcs12_host_state(struct kvm_vcpu *vcpu,
struct vmcs12 *vmcs12)
{
struct kvm_segment seg;
- u32 entry_failure_code;
+ u32 ign;

if (vmcs12->vm_exit_controls & VM_EXIT_LOAD_IA32_EFER)
vcpu->arch.efer = vmcs12->host_ia32_efer;
@@ -3629,7 +3638,7 @@ static void load_vmcs12_host_state(struct kvm_vcpu *vcpu,
* Only PDPTE load can fail as the value of cr3 was checked on entry and
* couldn't have changed.
*/
- if (nested_vmx_load_cr3(vcpu, vmcs12->host_cr3, false, &entry_failure_code))
+ if (nested_vmx_load_cr3(vcpu, vmcs12->host_cr3, false, &ign))
nested_vmx_abort(vcpu, VMX_ABORT_LOAD_HOST_PDPTE_FAIL);

if (!enable_ept)
@@ -3727,7 +3736,7 @@ static void load_vmcs12_host_state(struct kvm_vcpu *vcpu,
vmx_update_msr_bitmap(vcpu);

if (nested_vmx_load_msr(vcpu, vmcs12->vm_exit_msr_load_addr,
- vmcs12->vm_exit_msr_load_count))
+ vmcs12->vm_exit_msr_load_count, &ign, &ign))
nested_vmx_abort(vcpu, VMX_ABORT_LOAD_HOST_MSR_FAIL);
}

@@ -5352,7 +5361,7 @@ static int vmx_set_nested_state(struct kvm_vcpu *vcpu,
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
struct vmcs12 *vmcs12;
- u32 exit_qual;
+ u32 ign;
int ret;

if (kvm_state->format != 0)
@@ -5465,9 +5474,9 @@ static int vmx_set_nested_state(struct kvm_vcpu *vcpu,
return -EINVAL;
}

- if (nested_vmx_check_controls(vcpu, vmcs12) ||
- nested_vmx_check_host_state(vcpu, vmcs12) ||
- nested_vmx_check_guest_state(vcpu, vmcs12, &exit_qual))
+ if (nested_vmx_check_controls(vcpu, vmcs12, &ign) ||
+ nested_vmx_check_host_state(vcpu, vmcs12, &ign) ||
+ nested_vmx_check_guest_state(vcpu, vmcs12, &ign, &ign))
return -EINVAL;

vmx->nested.dirty_vmcs12 = true;
--
2.21.0