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KVM: VMX: Fix host MSR_KERNEL_GS_BASE corruption 

enter_lmode() and exit_lmode() modify the guest's EFER.LMA before calling
vmx_set_efer().  However, the latter function depends on the value of EFER.LMA
to determine whether MSR_KERNEL_GS_BASE needs reloading, via
vmx_load_host_state().  With EFER.LMA changing under its feet, it took the
wrong choice and corrupted userspace's %gs.

This causes 32-on-64 host userspace to fault.

Fix not touching EFER.LMA; instead ask vmx_set_efer() to change it.

Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Avi Kivity 2010-07-06 11:30:49 +03:00
parent 815c4163b6
commit da38f43859
1 changed files with 2 additions and 5 deletions
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7
arch/x86/kvm/vmx.c
View File

@ -1744,18 +1744,15 @@ static void enter_lmode(struct kvm_vcpu *vcpu)
(guest_tr_ar & ~AR_TYPE_MASK)
| AR_TYPE_BUSY_64_TSS);
}
vcpu->arch.efer |= EFER_LMA;
vmx_set_efer(vcpu, vcpu->arch.efer);
vmx_set_efer(vcpu, vcpu->arch.efer | EFER_LMA);
}
static void exit_lmode(struct kvm_vcpu *vcpu)
{
vcpu->arch.efer &= ~EFER_LMA;
vmcs_write32(VM_ENTRY_CONTROLS,
vmcs_read32(VM_ENTRY_CONTROLS)
& ~VM_ENTRY_IA32E_MODE);
vmx_set_efer(vcpu, vcpu->arch.efer);
vmx_set_efer(vcpu, vcpu->arch.efer & ~EFER_LMA);
}
#endif