1 files changed, 54 insertions, 6 deletions

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 959cb59cfaeb..f0f9773f0b0f 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -51,6 +51,10 @@ module_param_named(flexpriority, flexpriority_enabled, bool, S_IRUGO);
 static int __read_mostly enable_ept = 1;
 module_param_named(ept, enable_ept, bool, S_IRUGO);
 
+static int __read_mostly enable_unrestricted_guest = 1;
+module_param_named(unrestricted_guest,
+                        enable_unrestricted_guest, bool, S_IRUGO);
+
 static int __read_mostly emulate_invalid_guest_state = 0;
 module_param(emulate_invalid_guest_state, bool, S_IRUGO);
 
@@ -279,6 +283,12 @@ static inline int cpu_has_vmx_ept(void)
                 SECONDARY_EXEC_ENABLE_EPT;
 }
 
+static inline int cpu_has_vmx_unrestricted_guest(void)
+{
+        return vmcs_config.cpu_based_2nd_exec_ctrl &
+                SECONDARY_EXEC_UNRESTRICTED_GUEST;
+}
+
 static inline int vm_need_virtualize_apic_accesses(struct kvm *kvm)
 {
         return flexpriority_enabled &&
@@ -1210,7 +1220,8 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf)
                 opt2 = SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES |
                         SECONDARY_EXEC_WBINVD_EXITING |
                         SECONDARY_EXEC_ENABLE_VPID |
-                        SECONDARY_EXEC_ENABLE_EPT;
+                        SECONDARY_EXEC_ENABLE_EPT |
+                        SECONDARY_EXEC_UNRESTRICTED_GUEST;
                 if (adjust_vmx_controls(min2, opt2,
                                         MSR_IA32_VMX_PROCBASED_CTLS2,
                                         &_cpu_based_2nd_exec_control) < 0)
@@ -1340,8 +1351,13 @@ static __init int hardware_setup(void)
         if (!cpu_has_vmx_vpid())
                 enable_vpid = 0;
 
-        if (!cpu_has_vmx_ept())
+        if (!cpu_has_vmx_ept()) {
                 enable_ept = 0;
+                enable_unrestricted_guest = 0;
+        }
+
+        if (!cpu_has_vmx_unrestricted_guest())
+                enable_unrestricted_guest = 0;
 
         if (!cpu_has_vmx_flexpriority())
                 flexpriority_enabled = 0;
@@ -1440,6 +1456,9 @@ static void enter_rmode(struct kvm_vcpu *vcpu)
         unsigned long flags;
         struct vcpu_vmx *vmx = to_vmx(vcpu);
 
+        if (enable_unrestricted_guest)
+                return;
+
         vmx->emulation_required = 1;
         vcpu->arch.rmode.vm86_active = 1;
 
@@ -1593,7 +1612,6 @@ static void ept_update_paging_mode_cr0(unsigned long *hw_cr0,
                               CPU_BASED_CR3_STORE_EXITING));
                 vcpu->arch.cr0 = cr0;
                 vmx_set_cr4(vcpu, vcpu->arch.cr4);
-                *hw_cr0 |= X86_CR0_PE | X86_CR0_PG;
                 *hw_cr0 &= ~X86_CR0_WP;
         } else if (!is_paging(vcpu)) {
                 /* From nonpaging to paging */
@@ -1620,8 +1638,13 @@ static void ept_update_paging_mode_cr4(unsigned long *hw_cr4,
 
 static void vmx_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)
 {
-        unsigned long hw_cr0 = (cr0 & ~KVM_GUEST_CR0_MASK) |
-                                KVM_VM_CR0_ALWAYS_ON;
+        unsigned long hw_cr0;
+
+        if (enable_unrestricted_guest)
+                hw_cr0 = (cr0 & ~KVM_GUEST_CR0_MASK_UNRESTRICTED_GUEST)
+                        | KVM_VM_CR0_ALWAYS_ON_UNRESTRICTED_GUEST;
+        else
+                hw_cr0 = (cr0 & ~KVM_GUEST_CR0_MASK) | KVM_VM_CR0_ALWAYS_ON;
 
         vmx_fpu_deactivate(vcpu);
 
@@ -1786,6 +1809,21 @@ static void vmx_set_segment(struct kvm_vcpu *vcpu,
                 ar = 0xf3;
         } else
                 ar = vmx_segment_access_rights(var);
+
+        /*
+         *   Fix the "Accessed" bit in AR field of segment registers for older
+         * qemu binaries.
+         *   IA32 arch specifies that at the time of processor reset the
+         * "Accessed" bit in the AR field of segment registers is 1. And qemu
+         * is setting it to 0 in the usedland code. This causes invalid guest
+         * state vmexit when "unrestricted guest" mode is turned on.
+         *    Fix for this setup issue in cpu_reset is being pushed in the qemu
+         * tree. Newer qemu binaries with that qemu fix would not need this
+         * kvm hack.
+         */
+        if (enable_unrestricted_guest && (seg != VCPU_SREG_LDTR))
+                ar |= 0x1; /* Accessed */
+
         vmcs_write32(sf->ar_bytes, ar);
 }
 
@@ -2082,11 +2120,19 @@ out:
 static void seg_setup(int seg)
 {
         struct kvm_vmx_segment_field *sf = &kvm_vmx_segment_fields[seg];
+        unsigned int ar;
 
         vmcs_write16(sf->selector, 0);
         vmcs_writel(sf->base, 0);
         vmcs_write32(sf->limit, 0xffff);
-        vmcs_write32(sf->ar_bytes, 0xf3);
+        if (enable_unrestricted_guest) {
+                ar = 0x93;
+                if (seg == VCPU_SREG_CS)
+                        ar |= 0x08; /* code segment */
+        } else
+                ar = 0xf3;
+
+        vmcs_write32(sf->ar_bytes, ar);
 }
 
 static int alloc_apic_access_page(struct kvm *kvm)
@@ -2229,6 +2275,8 @@ static int vmx_vcpu_setup(struct vcpu_vmx *vmx)
                         exec_control &= ~SECONDARY_EXEC_ENABLE_VPID;
                 if (!enable_ept)
                         exec_control &= ~SECONDARY_EXEC_ENABLE_EPT;
+                if (!enable_unrestricted_guest)
+                        exec_control &= ~SECONDARY_EXEC_UNRESTRICTED_GUEST;
                 vmcs_write32(SECONDARY_VM_EXEC_CONTROL, exec_control);
         }