[ 117/133] Revert "KVM: VMX: Fix KVM_SET_SREGS with big real mode segments"

Greg Kroah-Hartman
2012-10-11T00:16:04Z

From: Avi Kivity <avi@redhat.com>

This reverts commit b398aa3174cd. It
causes a regression with some versions of ipxe. 3.6 has other fixes
that cannot be backported to 3.5, so it is better to live with the
minor problem that b398aa3174cd fixes.

https://bugzilla.redhat.com/show_bug.cgi?id=854983

Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/x86/kvm/vmx.c | 74 ++++++++++-------------------------------------------
1 file changed, 14 insertions(+), 60 deletions(-)

--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -615,10 +615,6 @@ 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);
@@ -2767,7 +2763,6 @@ static void enter_rmode(struct kvm_vcpu
{
unsigned long flags;
struct vcpu_vmx *vmx = to_vmx(vcpu);
- struct kvm_segment var;

if (enable_unrestricted_guest)
return;
@@ -2811,23 +2806,20 @@ static void enter_rmode(struct kvm_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);
-
- vmx_get_segment(vcpu, &var, VCPU_SREG_DS);
- vmx_set_segment(vcpu, &var, VCPU_SREG_DS);
-
- 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);
+ vmcs_write16(GUEST_SS_SELECTOR, vmcs_readl(GUEST_SS_BASE) >> 4);
+ vmcs_write32(GUEST_SS_LIMIT, 0xffff);
+ vmcs_write32(GUEST_SS_AR_BYTES, 0xf3);
+
+ 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);
+
+ 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);
@@ -3230,44 +3222,6 @@ static void vmx_set_segment(struct kvm_v

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)