Re: [PATCH v6 2/7] KVM: VMX: Use is_64_bit_mode() to check 64-bit mode

[Sean Christopherson <seanjc@google.com>]

On Mon, Mar 20, 2023, Chao Gao wrote:
> On Sun, Mar 19, 2023 at 04:49:22PM +0800, Binbin Wu wrote:
> >get_vmx_mem_address() and sgx_get_encls_gva() use is_long_mode()
> >to check 64-bit mode. Should use is_64_bit_mode() instead.
> >
> >Fixes: f9eb4af67c9d ("KVM: nVMX: VMX instructions: add checks for #GP/#SS exceptions")
> >Fixes: 70210c044b4e ("KVM: VMX: Add SGX ENCLS[ECREATE] handler to enforce CPUID restrictions")
> 
> It is better to split this patch into two: one for nested and one for
> SGX.
> 
> It is possible that there is a kernel release which has just one of
> above two flawed commits, then this fix patch cannot be applied cleanly
> to the release.

The nVMX code isn't buggy, VMX instructions #UD in compatibility mode, and except
for VMCALL, that #UD has higher priority than VM-Exit interception.  So I'd say
just drop the nVMX side of things.

I could have sworn ENCLS had the same behavior, but the SDM disagrees.  Though why
on earth ENCLS is allowed in compatibility mode is beyond me.  ENCLU I can kinda
sorta understand, but ENCLS?!?!!