KVM: x86: do not pass poisoned hva to __kvm_set_memory_region

__kvm_set_memory_region does not use the hva at all, so trying to
catch use-after-delete is pointless and, worse, it fails access_ok
now that we apply it to all memslots including private kernel ones.
This fixes an AVIC regression.

Fixes: 09d952c971a5 ("KVM: check userspace_addr for all memslots")
Reported-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 290784b..00c88c2 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9951,13 +9951,8 @@ int __x86_set_memory_region(struct kvm *kvm, int id, gpa_t gpa, u32 size)
                if (!slot || !slot->npages)
                        return 0;
 
-               /*
-                * Stuff a non-canonical value to catch use-after-delete.  This
-                * ends up being 0 on 32-bit KVM, but there's no better
-                * alternative.
-                */
-               hva = (unsigned long)(0xdeadull << 48);
                old_npages = slot->npages;
+               hva = 0;
        }
 
        for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) {