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authorPaolo Bonzini <pbonzini@redhat.com>2021-07-08 13:15:57 -0400
committerPaolo Bonzini <pbonzini@redhat.com>2021-07-14 12:14:27 -0400
commitf3cf800778e9e76b2387d00c9bfbc2e16efdb7ed (patch)
tree783e27546a8d65df254f59b5a024dc42eb390582 /virt
parentb8917b4ae44d1b945f6fba3d8ee6777edb44633b (diff)
parentcd4220d23bf3f43cf720e82bdee681f383433ae2 (diff)
Merge tag 'kvm-s390-master-5.14-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux into HEAD
KVM: selftests: Fixes - provide memory model for IBM z196 and zEC12 - do not require 64GB of memory
Diffstat (limited to 'virt')
-rw-r--r--virt/kvm/kvm_main.c19
1 files changed, 17 insertions, 2 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 3dcc2abbfc60..f7445c3bcd90 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2175,6 +2175,13 @@ static bool vma_is_valid(struct vm_area_struct *vma, bool write_fault)
return true;
}
+static int kvm_try_get_pfn(kvm_pfn_t pfn)
+{
+ if (kvm_is_reserved_pfn(pfn))
+ return 1;
+ return get_page_unless_zero(pfn_to_page(pfn));
+}
+
static int hva_to_pfn_remapped(struct vm_area_struct *vma,
unsigned long addr, bool *async,
bool write_fault, bool *writable,
@@ -2224,13 +2231,21 @@ static int hva_to_pfn_remapped(struct vm_area_struct *vma,
* Whoever called remap_pfn_range is also going to call e.g.
* unmap_mapping_range before the underlying pages are freed,
* causing a call to our MMU notifier.
+ *
+ * Certain IO or PFNMAP mappings can be backed with valid
+ * struct pages, but be allocated without refcounting e.g.,
+ * tail pages of non-compound higher order allocations, which
+ * would then underflow the refcount when the caller does the
+ * required put_page. Don't allow those pages here.
*/
- kvm_get_pfn(pfn);
+ if (!kvm_try_get_pfn(pfn))
+ r = -EFAULT;
out:
pte_unmap_unlock(ptep, ptl);
*p_pfn = pfn;
- return 0;
+
+ return r;
}
/*