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: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index ac1c4de3a484..978f402006ee 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -630,7 +630,7 @@ static int mmu_spte_clear_track_bits(u64 *sptep)
          * kvm mmu, before reclaiming the page, we should
          * unmap it from mmu first.
          */
-        WARN_ON(!kvm_is_mmio_pfn(pfn) && !page_count(pfn_to_page(pfn)));
+        WARN_ON(!kvm_is_reserved_pfn(pfn) && !page_count(pfn_to_page(pfn)));
 
         if (!shadow_accessed_mask || old_spte & shadow_accessed_mask)
                 kvm_set_pfn_accessed(pfn);
@@ -2461,7 +2461,7 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
                 spte |= PT_PAGE_SIZE_MASK;
         if (tdp_enabled)
                 spte |= kvm_x86_ops->get_mt_mask(vcpu, gfn,
-                        kvm_is_mmio_pfn(pfn));
+                        kvm_is_reserved_pfn(pfn));
 
         if (host_writable)
                 spte |= SPTE_HOST_WRITEABLE;
@@ -2737,7 +2737,7 @@ static void transparent_hugepage_adjust(struct kvm_vcpu *vcpu,
          * PT_PAGE_TABLE_LEVEL and there would be no adjustment done
          * here.
          */
-        if (!is_error_noslot_pfn(pfn) && !kvm_is_mmio_pfn(pfn) &&
+        if (!is_error_noslot_pfn(pfn) && !kvm_is_reserved_pfn(pfn) &&
             level == PT_PAGE_TABLE_LEVEL &&
             PageTransCompound(pfn_to_page(pfn)) &&
             !has_wrprotected_page(vcpu->kvm, gfn, PT_DIRECTORY_LEVEL)) {