KVM: MMU: handle page removal with shadow mapping
Do not assume that a shadow mapping will always point to the same host
frame number. Fixes crash with madvise(MADV_DONTNEED).
[avi: move after first printk(), add another printk()]
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index e49c4d4..4ba85d9 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -892,14 +892,25 @@
int *ptwrite, gfn_t gfn, struct page *page)
{
u64 spte;
- int was_rmapped = is_rmap_pte(*shadow_pte);
+ int was_rmapped = 0;
int was_writeble = is_writeble_pte(*shadow_pte);
+ hfn_t host_pfn = (*shadow_pte & PT64_BASE_ADDR_MASK) >> PAGE_SHIFT;
pgprintk("%s: spte %llx access %x write_fault %d"
" user_fault %d gfn %lx\n",
__FUNCTION__, *shadow_pte, pt_access,
write_fault, user_fault, gfn);
+ if (is_rmap_pte(*shadow_pte)) {
+ if (host_pfn != page_to_pfn(page)) {
+ pgprintk("hfn old %lx new %lx\n",
+ host_pfn, page_to_pfn(page));
+ rmap_remove(vcpu->kvm, shadow_pte);
+ }
+ else
+ was_rmapped = 1;
+ }
+
/*
* We don't set the accessed bit, since we sometimes want to see
* whether the guest actually used the pte (in order to detect