Re: [PATCH v1 1/4] KVM: MMU: check guest CR3 reserved bits based on its physical address width.
From: Yu Zhang
Date: Mon Aug 14 2017 - 08:01:25 EST
On 8/14/2017 3:36 PM, Paolo Bonzini wrote:
On 12/08/2017 15:35, Yu Zhang wrote:
+ ctxt->ops->get_cpuid(ctxt, &eax, NULL, NULL, NULL);
+ maxphyaddr = eax * 0xff;
This is "&", not "*". You can also use rsvd_bits here.
Oops. Sorry for the typo. :-)
+ rsvd = (~((1UL << maxphyaddr) - 1)) &
+ ~CR3_PCID_INVD;
+ }
if (new_val & rsvd)
return emulate_gp(ctxt, 0);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index e40a779..d9100c4 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -813,10 +813,10 @@ int kvm_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3)
return 0;
}
- if (is_long_mode(vcpu)) {
- if (cr3 & CR3_L_MODE_RESERVED_BITS)
- return 1;
- } else if (is_pae(vcpu) && is_paging(vcpu) &&
+ if (is_long_mode(vcpu) &&
+ (cr3 & rsvd_bits(cpuid_maxphyaddr(vcpu), 63)))
+ return 1;
62 is a little better, since 63 is the PCID invalidate bit.
Got it. Both kvm_set_cr3() and check_cr_write() should use
rsvd_bits(maxphyaddr, 62) .
Thanks
Yu
Paolo
+ else if (is_pae(vcpu) && is_paging(vcpu) &&
!load_pdptrs(vcpu, vcpu->arch.walk_mmu, cr3))
return 1;