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

Wanpeng Li · bonzini · commit a780a3ea6282 · 2018-05-14T18:14:16.000+02:00
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 'd1cd3ce900441 ("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: d1cd3ce (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>
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
@@ -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)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
@@ -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))

Original file line number	Diff line number	Diff line change
`@@ -856,7 +856,7 @@ int kvm_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3)`
`856`	`856`	`}`
`857`	`857`
`858`	`858`	`if (is_long_mode(vcpu) &&`
`859`		`- (cr3 & rsvd_bits(cpuid_maxphyaddr(vcpu), 62)))`
	`859`	`+ (cr3 & rsvd_bits(cpuid_maxphyaddr(vcpu), 63)))`
`860`	`860`	`return 1;`
`861`	`861`	`else if (is_pae(vcpu) && is_paging(vcpu) &&`
`862`	`862`	`!load_pdptrs(vcpu, vcpu->arch.walk_mmu, cr3))`