Re: [PATCH 0/4] Process some MMIO-related errors without KVM exit

[Sean Christopherson]

On Mon, Sep 23, 2024, Ivan Orlov wrote:
> Currently, KVM may return a variety of internal errors to VMM when
> accessing MMIO, and some of them could be gracefully handled on the KVM
> level instead. Moreover, some of the MMIO-related errors are handled
> differently in VMX in comparison with SVM, which produces certain
> inconsistency and should be fixed. This patch series introduces
> KVM-level handling for the following situations:
> 
> 1) Guest is accessing MMIO during event delivery: triple fault instead
> of internal error on VMX and infinite loop on SVM
> 
> 2) Guest fetches an instruction from MMIO: inject #UD and resume guest
> execution without internal error

No.  This is not architectural behavior.  It's not even remotely close to
architectural behavior.  KVM's behavior isn't great, but making up _guest visible_
behavior is not going to happen.