kvm: fix kvm_is_mmio_pfn() and rename to kvm_is_reserved_pfn()

This reverts commit 85c8555ff0 ("KVM: check for !is_zero_pfn() in
kvm_is_mmio_pfn()") and renames the function to kvm_is_reserved_pfn.

The problem being addressed by the patch above was that some ARM code
based the memory mapping attributes of a pfn on the return value of
kvm_is_mmio_pfn(), whose name indeed suggests that such pfns should
be mapped as device memory.

However, kvm_is_mmio_pfn() doesn't do quite what it says on the tin,
and the existing non-ARM users were already using it in a way which
suggests that its name should probably have been 'kvm_is_reserved_pfn'
from the beginning, e.g., whether or not to call get_page/put_page on
it etc. This means that returning false for the zero page is a mistake
and the patch above should be reverted.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

1 files changed, 8 insertions, 8 deletions

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 25ffac9e947d..3cee7b167052 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -107,10 +107,10 @@ EXPORT_SYMBOL_GPL(kvm_rebooting);
 
 static bool largepages_enabled = true;
 
-bool kvm_is_mmio_pfn(pfn_t pfn)
+bool kvm_is_reserved_pfn(pfn_t pfn)
 {
         if (pfn_valid(pfn))
-                return !is_zero_pfn(pfn) && PageReserved(pfn_to_page(pfn));
+                return PageReserved(pfn_to_page(pfn));
 
         return true;
 }
@@ -1321,7 +1321,7 @@ static pfn_t hva_to_pfn(unsigned long addr, bool atomic, bool *async,
         else if ((vma->vm_flags & VM_PFNMAP)) {
                 pfn = ((addr - vma->vm_start) >> PAGE_SHIFT) +
                         vma->vm_pgoff;
-                BUG_ON(!kvm_is_mmio_pfn(pfn));
+                BUG_ON(!kvm_is_reserved_pfn(pfn));
         } else {
                 if (async && vma_is_valid(vma, write_fault))
                         *async = true;
@@ -1427,7 +1427,7 @@ static struct page *kvm_pfn_to_page(pfn_t pfn)
         if (is_error_noslot_pfn(pfn))
                 return KVM_ERR_PTR_BAD_PAGE;
 
-        if (kvm_is_mmio_pfn(pfn)) {
+        if (kvm_is_reserved_pfn(pfn)) {
                 WARN_ON(1);
                 return KVM_ERR_PTR_BAD_PAGE;
         }
@@ -1456,7 +1456,7 @@ EXPORT_SYMBOL_GPL(kvm_release_page_clean);
 
 void kvm_release_pfn_clean(pfn_t pfn)
 {
-        if (!is_error_noslot_pfn(pfn) && !kvm_is_mmio_pfn(pfn))
+        if (!is_error_noslot_pfn(pfn) && !kvm_is_reserved_pfn(pfn))
                 put_page(pfn_to_page(pfn));
 }
 EXPORT_SYMBOL_GPL(kvm_release_pfn_clean);
@@ -1477,7 +1477,7 @@ static void kvm_release_pfn_dirty(pfn_t pfn)
 
 void kvm_set_pfn_dirty(pfn_t pfn)
 {
-        if (!kvm_is_mmio_pfn(pfn)) {
+        if (!kvm_is_reserved_pfn(pfn)) {
                 struct page *page = pfn_to_page(pfn);
                 if (!PageReserved(page))
                         SetPageDirty(page);
@@ -1487,14 +1487,14 @@ EXPORT_SYMBOL_GPL(kvm_set_pfn_dirty);
 
 void kvm_set_pfn_accessed(pfn_t pfn)
 {
-        if (!kvm_is_mmio_pfn(pfn))
+        if (!kvm_is_reserved_pfn(pfn))
                 mark_page_accessed(pfn_to_page(pfn));
 }
 EXPORT_SYMBOL_GPL(kvm_set_pfn_accessed);
 
 void kvm_get_pfn(pfn_t pfn)
 {
-        if (!kvm_is_mmio_pfn(pfn))
+        if (!kvm_is_reserved_pfn(pfn))
                 get_page(pfn_to_page(pfn));
 }
 EXPORT_SYMBOL_GPL(kvm_get_pfn);