Re: [PATCH 5/6 v5][KVM nVMX]: nested_vmx_check_vmentry_postreqs() should return VMX_EXIT_REASONS_FAILED_VMENTRY | EXIT_REASON_INVALID_STATE for error conditions

[Sean Christopherson <sean.j.christopherson@intel.com>]

On Wed, Apr 10, 2019 at 07:05:30PM +0200, Paolo Bonzini wrote:
> On 10/04/19 18:08, Sean Christopherson wrote:
> > Good point, though IMO it'd be better to go one step further and actually
> > consume the return value in nested_vmx_enter_non_root_mode().  For me,
> > having the exit reason in nested_vmx_check_vmentry_postreqs() is a nice
> > mental reminder that "postreqs" is referring to checks that happen once
> > the CPU has "committed" to VM-Enter.
> 
> It's certainly better if you don't have to return
> VMX_EXIT_REASONS_FAILED_VMENTRY.  However, I think it still complicates
> things a bit, after all the result is always EXIT_REASON_INVALID_STATE.
> 
> The SDM says "VM-entry failure due to invalid guest state. A VM entry
> failed one of the checks identified in Section 26.3.1" so the bool (or
> 0/-EINVAL) return code is a nice reminder that the function covers a
> subset of 26.3.1.

Heh, for me, returning EXIT_REASON_INVALID_STATE is the reminder that
the function covers 26.3.1.

What if we rename the function to nested_vmx_check_vmentry_guest_state()?
My desire to return the exit reason mostly stems from the name "postreqs"
since I tend to forget what "postreqs" is referring to.  And it'd be more
appropriate since the MSR load checks are handled elsewhere and really
should be considered "postreqs" as well.