KVM: VMX: give unrestricted guest full control of CR3

Now CR3 is not forced to a host-controlled value when paging is
disabled in an unrestricted guest, CR3 load/store exiting can be
left disabled (for an unrestricted guest).  And because CR0.WP
and CR4.PAE/PSE are also not force to host-controlled values,
all of ept_update_paging_mode_cr0() is no longer needed, i.e.
skip ept_update_paging_mode_cr0() for an unrestricted guest.

Because MOV CR3 no longer exits when paging is disabled for an
unrestricted guest, vmx_decache_cr3() must always read GUEST_CR3
from the VMCS for an unrestricted guest.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index d35e5c6..c517e96 100644 (file)
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -4314,7 +4314,7 @@ static void vmx_decache_cr0_guest_bits(struct kvm_vcpu *vcpu)
 
 static void vmx_decache_cr3(struct kvm_vcpu *vcpu)
 {
-       if (enable_ept && is_paging(vcpu))
+       if (enable_unrestricted_guest || (enable_ept && is_paging(vcpu)))
                vcpu->arch.cr3 = vmcs_readl(GUEST_CR3);
        __set_bit(VCPU_EXREG_CR3, (ulong *)&vcpu->arch.regs_avail);
 }
@@ -4451,7 +4451,7 @@ static void vmx_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)
        }
 #endif
 
-       if (enable_ept)
+       if (enable_ept && !enable_unrestricted_guest)
                ept_update_paging_mode_cr0(&hw_cr0, cr0, vcpu);
 
        vmcs_writel(CR0_READ_SHADOW, cr0);