1 files changed, 58 insertions, 12 deletions

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 396148ab089b..f78662ec8677 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -618,6 +618,10 @@ static void kvm_cpu_vmxon(u64 addr);
 static void kvm_cpu_vmxoff(void);
 static void vmx_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3);
 static int vmx_set_tss_addr(struct kvm *kvm, unsigned int addr);
+static void vmx_set_segment(struct kvm_vcpu *vcpu,
+                            struct kvm_segment *var, int seg);
+static void vmx_get_segment(struct kvm_vcpu *vcpu,
+                            struct kvm_segment *var, int seg);
 
 static DEFINE_PER_CPU(struct vmcs *, vmxarea);
 static DEFINE_PER_CPU(struct vmcs *, current_vmcs);
@@ -2782,6 +2786,7 @@ static void enter_rmode(struct kvm_vcpu *vcpu)
 {
         unsigned long flags;
         struct vcpu_vmx *vmx = to_vmx(vcpu);
+        struct kvm_segment var;
 
         if (enable_unrestricted_guest)
                 return;
@@ -2825,20 +2830,23 @@ static void enter_rmode(struct kvm_vcpu *vcpu)
         if (emulate_invalid_guest_state)
                 goto continue_rmode;
 
-        vmcs_write16(GUEST_SS_SELECTOR, vmcs_readl(GUEST_SS_BASE) >> 4);
-        vmcs_write32(GUEST_SS_LIMIT, 0xffff);
-        vmcs_write32(GUEST_SS_AR_BYTES, 0xf3);
+        vmx_get_segment(vcpu, &var, VCPU_SREG_SS);
+        vmx_set_segment(vcpu, &var, VCPU_SREG_SS);
+
+        vmx_get_segment(vcpu, &var, VCPU_SREG_CS);
+        vmx_set_segment(vcpu, &var, VCPU_SREG_CS);
+
+        vmx_get_segment(vcpu, &var, VCPU_SREG_ES);
+        vmx_set_segment(vcpu, &var, VCPU_SREG_ES);
 
-        vmcs_write32(GUEST_CS_AR_BYTES, 0xf3);
-        vmcs_write32(GUEST_CS_LIMIT, 0xffff);
-        if (vmcs_readl(GUEST_CS_BASE) == 0xffff0000)
-                vmcs_writel(GUEST_CS_BASE, 0xf0000);
-        vmcs_write16(GUEST_CS_SELECTOR, vmcs_readl(GUEST_CS_BASE) >> 4);
+        vmx_get_segment(vcpu, &var, VCPU_SREG_DS);
+        vmx_set_segment(vcpu, &var, VCPU_SREG_DS);
 
-        fix_rmode_seg(VCPU_SREG_ES, &vmx->rmode.es);
-        fix_rmode_seg(VCPU_SREG_DS, &vmx->rmode.ds);
-        fix_rmode_seg(VCPU_SREG_GS, &vmx->rmode.gs);
-        fix_rmode_seg(VCPU_SREG_FS, &vmx->rmode.fs);
+        vmx_get_segment(vcpu, &var, VCPU_SREG_GS);
+        vmx_set_segment(vcpu, &var, VCPU_SREG_GS);
+
+        vmx_get_segment(vcpu, &var, VCPU_SREG_FS);
+        vmx_set_segment(vcpu, &var, VCPU_SREG_FS);
 
 continue_rmode:
         kvm_mmu_reset_context(vcpu);
@@ -3243,6 +3251,44 @@ static void vmx_set_segment(struct kvm_vcpu *vcpu,
 
         vmcs_write32(sf->ar_bytes, ar);
         __clear_bit(VCPU_EXREG_CPL, (ulong *)&vcpu->arch.regs_avail);
+
+        /*
+         * Fix segments for real mode guest in hosts that don't have
+         * "unrestricted_mode" or it was disabled.
+         * This is done to allow migration of the guests from hosts with
+         * unrestricted guest like Westmere to older host that don't have
+         * unrestricted guest like Nehelem.
+         */
+        if (!enable_unrestricted_guest && vmx->rmode.vm86_active) {
+                switch (seg) {
+                case VCPU_SREG_CS:
+                        vmcs_write32(GUEST_CS_AR_BYTES, 0xf3);
+                        vmcs_write32(GUEST_CS_LIMIT, 0xffff);
+                        if (vmcs_readl(GUEST_CS_BASE) == 0xffff0000)
+                                vmcs_writel(GUEST_CS_BASE, 0xf0000);
+                        vmcs_write16(GUEST_CS_SELECTOR,
+                                     vmcs_readl(GUEST_CS_BASE) >> 4);
+                        break;
+                case VCPU_SREG_ES:
+                        fix_rmode_seg(VCPU_SREG_ES, &vmx->rmode.es);
+                        break;
+                case VCPU_SREG_DS:
+                        fix_rmode_seg(VCPU_SREG_DS, &vmx->rmode.ds);
+                        break;
+                case VCPU_SREG_GS:
+                        fix_rmode_seg(VCPU_SREG_GS, &vmx->rmode.gs);
+                        break;
+                case VCPU_SREG_FS:
+                        fix_rmode_seg(VCPU_SREG_FS, &vmx->rmode.fs);
+                        break;
+                case VCPU_SREG_SS:
+                        vmcs_write16(GUEST_SS_SELECTOR,
+                                     vmcs_readl(GUEST_SS_BASE) >> 4);
+                        vmcs_write32(GUEST_SS_LIMIT, 0xffff);
+                        vmcs_write32(GUEST_SS_AR_BYTES, 0xf3);
+                        break;
+                }
+        }
 }
 
 static void vmx_get_cs_db_l_bits(struct kvm_vcpu *vcpu, int *db, int *l)