Re: [PATCH v3 13/13] KVM: x86: emulator/smm: preserve interrupt shadow in SMRAM

[Sean Christopherson]

On Wed, Aug 03, 2022, Maxim Levitsky wrote:
> @@ -518,7 +519,8 @@ struct kvm_smram_state_32 {
>  	u32 reserved1[62];
>  	u32 smbase;
>  	u32 smm_revision;
> -	u32 reserved2[5];
> +	u32 reserved2[4];
> +	u32 int_shadow; /* KVM extension */

Looking at this with fresh(er) eyes, I agree with Jim: KVM shouldn't add its own
fields in SMRAM.  There's no need to use vmcb/vmcs memory either, just add fields
in kvm_vcpu_arch to save/restore the state across SMI/RSM, and then borrow VMX's
approach of supporting migration by adding flags to do out-of-band migration,
e.g. KVM_STATE_NESTED_SMM_STI_BLOCKING and KVM_STATE_NESTED_SMM_MOV_SS_BLOCKING.

	/* SMM state that's not saved in SMRAM. */
	struct {
		struct {
			u8 interruptibility;
		} smm;
	} nested;

That'd finally give us an excuse to move nested_run_pending to common code too :-)