Commit a780a3ea authored May 13, 2018 by Wanpeng Li Committed by Paolo Bonzini May 14, 2018

KVM: X86: Fix reserved bits check for MOV to CR3



MSB of CR3 is a reserved bit if the PCIDE bit is not set in CR4.
It should be checked when PCIDE bit is not set, however commit
'd1cd3ce9 ("KVM: MMU: check guest CR3 reserved bits based on
its physical address width")' removes the bit 63 checking
unconditionally. This patch fixes it by checking bit 63 of CR3
when PCIDE bit is not set in CR4.

Fixes: d1cd3ce9 (KVM: MMU: check guest CR3 reserved bits based on its physical address width)
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Liran Alon <liran.alon@oracle.com>
Cc: stable@vger.kernel.org
Reviewed-by: Junaid Shahid <junaids@google.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

parent 64f7a115

arch/x86/kvm/emulate.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -4189,7 +4189,9 @@ static int check_cr_write(struct x86_emulate_ctxt *ctxt)
		maxphyaddr = eax & 0xff;
		else
		maxphyaddr = 36;
		rsvd = rsvd_bits(maxphyaddr, 62);
		rsvd = rsvd_bits(maxphyaddr, 63);
		if (ctxt->ops->get_cr(ctxt, 4) & X86_CR4_PCIDE)
		rsvd &= ~CR3_PCID_INVD;
		}

		if (new_val & rsvd)

arch/x86/kvm/x86.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -856,7 +856,7 @@ int kvm_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3)
		}

		if (is_long_mode(vcpu) &&
		(cr3 & rsvd_bits(cpuid_maxphyaddr(vcpu), 62)))
		(cr3 & rsvd_bits(cpuid_maxphyaddr(vcpu), 63)))
		return 1;
		else if (is_pae(vcpu) && is_paging(vcpu) &&
		!load_pdptrs(vcpu, vcpu->arch.walk_mmu, cr3))

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