Re: [PATCH 2/7] KVM: x86/mmu: Return RET_PF* instead of 1 in kvm_mmu_page_fault()

Edgecombe, Rick P
2025-01-14T22:25:13Z

On Mon, 2025-01-13 at 10:11 +0800, Yan Zhao wrote:
> Return RET_PF* (excluding RET_PF_EMULATE/RET_PF_CONTINUE/RET_PF_INVALID)
> instead of 1 in kvm_mmu_page_fault().
>
> The callers of kvm_mmu_page_fault() are KVM page fault handlers (i.e.,
> npf_interception(), handle_ept_misconfig(), __vmx_handle_ept_violation(),
> kvm_handle_page_fault()). They either check if the return value is > 0 (as
> in npf_interception()) or pass it further to vcpu_run() to decide whether
> to break out of the kernel loop and return to the user when r <= 0.
> Therefore, returning any positive value is equivalent to returning 1.
>
> Warn if r == RET_PF_CONTINUE (which should not be a valid value) to ensure
> a positive return value.
>
> This is a preparation to allow TDX's EPT violation handler to check the
> RET_PF* value and retry internally for RET_PF_RETRY.
>
> No functional changes are intended.

Any reason why this can't go ahead of the TDX patches? Seems pretty generic
cleanup.