On Tue, Sep 13, 2022, Miaohe Lin wrote: > Use helper macro SPTE_ENT_PER_PAGE to get the number of spte entries > per page. Minor readability improvement. > > Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx> > --- Reviewed-by: Sean Christopherson <seanjc@xxxxxxxxxx> > arch/x86/kvm/mmu/mmu.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c > index 858bc53cfab4..45c532d00f78 100644 > --- a/arch/x86/kvm/mmu/mmu.c > +++ b/arch/x86/kvm/mmu/mmu.c > @@ -1645,7 +1645,7 @@ static int is_empty_shadow_page(u64 *spt) > u64 *pos; > u64 *end; > > - for (pos = spt, end = pos + PAGE_SIZE / sizeof(u64); pos != end; pos++) > + for (pos = spt, end = pos + SPTE_ENT_PER_PAGE; pos != end; pos++) This is buried under MMU_DEBUG, and turning that on to compile test, which requires manually changing kernel code to enable, results in some minor warnings. Given the existence of CONFIG_KVM_WERROR=y, I think it's safe to say this code hasn't been exercised in a very long time. E.g. this is literally the first time I've actually enabled MMU_DEBUG. This particular check seems like it would be quite useful, but the pgprintk() and rmap_printk() hooks, not so much. E.g. the knob is too coarse grained, and many of the prints now have tracepoints. So, unless someone actually actively uses MMU_DEBUG+dbg, I'm inclined to just delete pgprintk() and rmap_printk(), and then rename MMU_WARN_ON => KVM_MMU_WARN_ON and add a Kconfig for that, e.g. CONFIG_KVM_PROVE_MMU. Hmm, and maybe clean up this helper too, e.g. get rid of the pointer arithmetic, and take the full kvm_mmu_page so that the error message can print out things like the gfn (a host kernel pointer is going to be useless for debug). Thoughts? Objections?
