KVM: x86: reset pdptrs_from_userspace when exiting smm

When exiting SMM, pdpts are loaded again from the guest memory.

This fixes a theoretical bug, when exit from SMM triggers entry to the
nested guest which re-uses some of the migration
code which uses this flag as a workaround for a legacy userspace.

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20210913140954.165665-4-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 11017c94f0aa69773ab6b7d7634cb634e393fddd..ba70e8f11f2c29cd5782e671be0fdc25a1d296dd 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -7658,6 +7658,13 @@ static void kvm_smm_changed(struct kvm_vcpu *vcpu, bool entering_smm)
 
                /* Process a latched INIT or SMI, if any.  */
                kvm_make_request(KVM_REQ_EVENT, vcpu);
+
+               /*
+                * Even if KVM_SET_SREGS2 loaded PDPTRs out of band,
+                * on SMM exit we still need to reload them from
+                * guest memory
+                */
+               vcpu->arch.pdptrs_from_userspace = false;
        }
 
        kvm_mmu_reset_context(vcpu);