On Wed, Jan 15, 2025 at 06:24:43AM +0800, Edgecombe, Rick P wrote: > 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. Hmm, I wouldn't consider this a cleanup, as returning 1 to indicate continuation of the kernel loop is a well-established convention in arch/x86/kvm. Returning a positive RET_PF_* in this patch is primarily a preparatory step for the subsequent patch, "KVM: TDX: Retry locally in TDX EPT violation handler on RET_PF_RETRY".
