KVM: PPC: Use __kvm_faultin_pfn() to handle page faults on Book3s HV

Replace Book3s HV's homebrewed fault-in logic with __kvm_faultin_pfn(),
which functionally does pretty much the exact same thing.

Note, when the code was written, KVM indeed didn't do fast GUP without
"!atomic && !async", but that has long since changed (KVM tries fast GUP
for all writable mappings).

Signed-off-by: Sean Christopherson <seanjc@google.com>
Tested-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20241010182427.1434605-61-seanjc@google.com>

diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c
index 2f1d58984b41cde856e473afb82114cab349135e..f305395cf26e7b9c15e18ef70207337ba59cbef5 100644 (file)
--- a/arch/powerpc/kvm/book3s_64_mmu_hv.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c
@@ -603,27 +603,10 @@ int kvmppc_book3s_hv_page_fault(struct kvm_vcpu *vcpu,
        write_ok = writing;
        hva = gfn_to_hva_memslot(memslot, gfn);
 
-       /*
-        * Do a fast check first, since __gfn_to_pfn_memslot doesn't
-        * do it with !atomic && !async, which is how we call it.
-        * We always ask for write permission since the common case
-        * is that the page is writable.
-        */
-       if (get_user_page_fast_only(hva, FOLL_WRITE, &page)) {
-               write_ok = true;
-       } else {
-               /* Call KVM generic code to do the slow-path check */
-               pfn = __gfn_to_pfn_memslot(memslot, gfn, false, NULL,
-                                          writing, &write_ok);
-               if (is_error_noslot_pfn(pfn))
-                       return -EFAULT;
-               page = NULL;
-               if (pfn_valid(pfn)) {
-                       page = pfn_to_page(pfn);
-                       if (PageReserved(page))
-                               page = NULL;
-               }
-       }
+       pfn = __kvm_faultin_pfn(memslot, gfn, writing ? FOLL_WRITE : 0,
+                               &write_ok, &page);
+       if (is_error_noslot_pfn(pfn))
+               return -EFAULT;
 
        /*
         * Read the PTE from the process' radix tree and use that