KVM: VMX: Fix KVM_SET_SREGS with big real mode segments
authorOrit Wasserman <owasserm@redhat.com>
Thu, 31 May 2012 11:49:22 +0000 (14:49 +0300)
committerAvi Kivity <avi@redhat.com>
Tue, 5 Jun 2012 14:51:46 +0000 (17:51 +0300)
For example migration between Westmere and Nehelem hosts, caught in big real mode.

The code that fixes the segments for real mode guest was moved from enter_rmode
to vmx_set_segments. enter_rmode calls vmx_set_segments for each segment.

Signed-off-by: Orit Wasserman <owasserm@rehdat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
arch/x86/kvm/vmx.c

index 396148ab089b3dc4d546645f4251d34b4d31c172..f78662ec86774f924e52f7756133ff7711516a54 100644 (file)
@@ -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)