[PATCH v10 01/19] KVM: pfncache: Add a map helper function

Paul Durrant
2023-12-04T14:44:32Z

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>
---
Cc: Sean Christopherson <seanjc@google.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>

v8:
- Re-work commit comment.
- Fix CONFIG_HAS_IOMEM=n build.
---
virt/kvm/pfncache.c | 47 ++++++++++++++++++++++++++++-----------------
1 file changed, 29 insertions(+), 18 deletions(-)

diff --git a/virt/kvm/pfncache.c b/virt/kvm/pfncache.c
index 2d6aba677830..10842f1eeeae 100644
--- 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 @@ static int __kvm_gpc_refresh(struct gfn_to_pfn_cache *gpc, gpa_t gpa,
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);
--
2.39.2