KVM: pfncache: Add a map helper function

There is a pfncache unmap helper but mapping is open-coded. Arguably this
is fine because mapping is done in only one place, hva_to_pfn_retry(), but
adding the helper does make that function more readable.

No functional change intended.

Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Link: https://lore.kernel.org/r/20240215152916.1158-2-paul@xen.org
Signed-off-by: Sean Christopherson <seanjc@google.com>

diff --git a/virt/kvm/pfncache.c b/virt/kvm/pfncache.c
index 2d6aba6..10842f1 100644 (file)
--- a/virt/kvm/pfncache.c
+++ b/virt/kvm/pfncache.c
@@ -96,17 +96,32 @@ bool kvm_gpc_check(struct gfn_to_pfn_cache *gpc, unsigned long len)
 }
 EXPORT_SYMBOL_GPL(kvm_gpc_check);
 
-static void gpc_unmap_khva(kvm_pfn_t pfn, void *khva)
+static void *gpc_map(kvm_pfn_t pfn)
 {
-       /* Unmap the old pfn/page if it was mapped before. */
-       if (!is_error_noslot_pfn(pfn) && khva) {
-               if (pfn_valid(pfn))
-                       kunmap(pfn_to_page(pfn));
+       if (pfn_valid(pfn))
+               return kmap(pfn_to_page(pfn));
+
 #ifdef CONFIG_HAS_IOMEM
-               else
-                       memunmap(khva);
+       return memremap(pfn_to_hpa(pfn), PAGE_SIZE, MEMREMAP_WB);
+#else
+       return NULL;
 #endif
+}
+
+static void gpc_unmap(kvm_pfn_t pfn, void *khva)
+{
+       /* Unmap the old pfn/page if it was mapped before. */
+       if (is_error_noslot_pfn(pfn) || !khva)
+               return;
+
+       if (pfn_valid(pfn)) {
+               kunmap(pfn_to_page(pfn));
+               return;
        }
+
+#ifdef CONFIG_HAS_IOMEM
+       memunmap(khva);
+#endif
 }
 
 static inline bool mmu_notifier_retry_cache(struct kvm *kvm, unsigned long mmu_seq)
@@ -175,7 +190,7 @@ static kvm_pfn_t hva_to_pfn_retry(struct gfn_to_pfn_cache *gpc)
                         * the existing mapping and didn't create a new one.
                         */
                        if (new_khva != old_khva)
-                               gpc_unmap_khva(new_pfn, new_khva);
+                               gpc_unmap(new_pfn, new_khva);
 
                        kvm_release_pfn_clean(new_pfn);
 
@@ -193,15 +208,11 @@ static kvm_pfn_t hva_to_pfn_retry(struct gfn_to_pfn_cache *gpc)
                 * too must be done outside of gpc->lock!
                 */
                if (gpc->usage & KVM_HOST_USES_PFN) {
-                       if (new_pfn == gpc->pfn) {
+                       if (new_pfn == gpc->pfn)
                                new_khva = old_khva;
-                       } else if (pfn_valid(new_pfn)) {
-                               new_khva = kmap(pfn_to_page(new_pfn));
-#ifdef CONFIG_HAS_IOMEM
-                       } else {
-                               new_khva = memremap(pfn_to_hpa(new_pfn), PAGE_SIZE, MEMREMAP_WB);
-#endif
-                       }
+                       else
+                               new_khva = gpc_map(new_pfn);
+
                        if (!new_khva) {
                                kvm_release_pfn_clean(new_pfn);
                                goto out_error;
@@ -326,7 +337,7 @@ out_unlock:
        mutex_unlock(&gpc->refresh_lock);
 
        if (unmap_old)
-               gpc_unmap_khva(old_pfn, old_khva);
+               gpc_unmap(old_pfn, old_khva);
 
        return ret;
 }
@@ -412,7 +423,7 @@ void kvm_gpc_deactivate(struct gfn_to_pfn_cache *gpc)
                list_del(&gpc->list);
                spin_unlock(&kvm->gpc_lock);
 
-               gpc_unmap_khva(old_pfn, old_khva);
+               gpc_unmap(old_pfn, old_khva);
        }
 }
 EXPORT_SYMBOL_GPL(kvm_gpc_deactivate);