Re: [PATCH v6 08/14] KVM: arm64: Enable KVM_CAP_MEMORY_FAULT_INFO

[Sean Christopherson <seanjc@google.com>]

On Thu, Nov 09, 2023, Anish Moorthy wrote:
> On Thu, Nov 9, 2023 at 1:03 PM Anish Moorthy <amoorthy@google.com> wrote:
> >
> > TODO: Changelog -- and possibly just merge into the "god" arm commit?
> 
> *Facepalm*
> 
> Well as you can tell, I wasn't sure if there was anything to actually
> put in the long-form log. Lmk if you have suggestions

I think the right way to organize things is to have this chunk:

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index b1e5e42bdeb4..bc978260d2be 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -3309,6 +3309,10 @@ static int kvm_handle_error_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fa
                return RET_PF_RETRY;
        }

+       WARN_ON_ONCE(fault->goal_level != PG_LEVEL_4K);
+
+       kvm_prepare_memory_fault_exit(vcpu, gfn_to_gpa(fault->gfn), PAGE_SIZE,
+                                     fault->write, fault->exec, fault->is_private);
        return -EFAULT;
 }


be part of this patch.  Because otherwise, advertising KVM_CAP_MEMORY_FAULT_INFO
is a lie.  Userspace can't catch KVM in the lie, but that doesn't make it right.

That should in turn make it easier to write a useful changelog.