Re: [PATCH v5 2/7] nSVM: introduce smv->nested.save to cache save area fields

[Paolo Bonzini]

On 11/3/21 15:05, Emanuele Giuseppe Esposito wrote:
> Note that in svm_set_nested_state() we want to cache the L2
> save state only if we are in normal non guest mode, because
> otherwise it is not touched.

I think that call to nested_copy_vmcb_save_to_cache is not necessary at 
all, because svm->nested.save is not used afterwards and is not valid 
after VMRUN.

The relevant checks have already been done before:

        if (!(vcpu->arch.efer & EFER_SVME)) {
                /* GIF=1 and no guest mode are required if SVME=0.  */
                if (kvm_state->flags != KVM_STATE_NESTED_GIF_SET)
                        return -EINVAL;
        }

	...

        /*
         * Processor state contains L2 state.  Check that it is
         * valid for guest mode (see nested_vmcb_check_save).
         */
        cr0 = kvm_read_cr0(vcpu);
        if (((cr0 & X86_CR0_CD) == 0) && (cr0 & X86_CR0_NW))
                goto out_free;

(and all other checks are done by KVM_SET_SREGS, KVM_SET_DEBUGREGS etc.)

Paolo