[Quantal][PATCH 1/1] Revert "KVM: VMX: Fix KVM_SET_SREGS with big real mode segments"

[joseph.salisbury at canonical.com]

From: Joseph Salisbury <joseph.salisbury at canonical.com>

BugLink: http://bugs.launchpad.net/bugs/1045027

This reverts commit b398aa3174cdfd4d85964fa84004e53ce6a13cab.
---
 arch/x86/kvm/vmx.c |   70 +++++++++-------------------------------------------
 1 file changed, 12 insertions(+), 58 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index b2a349d..576a235 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -618,10 +618,6 @@ 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);
@@ -2791,7 +2787,6 @@ 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;
@@ -2835,23 +2830,20 @@ static void enter_rmode(struct kvm_vcpu *vcpu)
 	if (emulate_invalid_guest_state)
 		goto continue_rmode;
 
-	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_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_DS);
-	vmx_set_segment(vcpu, &var, VCPU_SREG_DS);
+	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_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);
+	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);
 
 continue_rmode:
 	kvm_mmu_reset_context(vcpu);
@@ -3256,44 +3248,6 @@ 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)
-- 
1.7.9.5