KVM: x86: change kvm_mmu_page_get_gfn BUG_ON to WARN_ON

commit e9f2a760b158551bfbef6db31d2cae45ab8072e5 upstream.

Note that in such a case it is quite likely that KVM will BUG_ON
in __pte_list_remove when the VM is closed.  However, there is no
immediate risk of memory corruption in the host so a WARN_ON is
enough and it lets you gather traces for debugging.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index bd5a63722d25163664b928490430f902ae45a106..17c2a123521572bab647f366c950d1a6fed35cba 100644 (file)
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1008,10 +1008,16 @@ static gfn_t kvm_mmu_page_get_gfn(struct kvm_mmu_page *sp, int index)
 
 static void kvm_mmu_page_set_gfn(struct kvm_mmu_page *sp, int index, gfn_t gfn)
 {
-       if (sp->role.direct)
-               BUG_ON(gfn != kvm_mmu_page_get_gfn(sp, index));
-       else
+       if (!sp->role.direct) {
                sp->gfns[index] = gfn;
+               return;
+       }
+
+       if (WARN_ON(gfn != kvm_mmu_page_get_gfn(sp, index)))
+               pr_err_ratelimited("gfn mismatch under direct page %llx "
+                                  "(expected %llx, got %llx)\n",
+                                  sp->gfn,
+                                  kvm_mmu_page_get_gfn(sp, index), gfn);
 }
 
 /*