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KVM: VMX: Fix host GDT.LIMIT corruption 

vmx does not restore GDT.LIMIT to the host value, instead it sets it to 64KB.
This means host userspace can learn a few bits of host memory.

Fix by reloading GDTR when we load other host state.

Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This commit is contained in:
Avi Kivity 2010-07-26 18:32:38 +03:00
parent 9a3aad7057
commit 3444d7da18
1 changed files with 4 additions and 0 deletions
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4
arch/x86/kvm/vmx.c
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@ -185,6 +185,7 @@ static void kvm_cpu_vmxoff(void);
static DEFINE_PER_CPU(struct vmcs *, vmxarea);
static DEFINE_PER_CPU(struct vmcs *, current_vmcs);
static DEFINE_PER_CPU(struct list_head, vcpus_on_cpu);
static DEFINE_PER_CPU(struct desc_ptr, host_gdt);
static unsigned long *vmx_io_bitmap_a;
static unsigned long *vmx_io_bitmap_b;
@ -871,6 +872,7 @@ static void __vmx_load_host_state(struct vcpu_vmx *vmx)
#endif
if (current_thread_info()->status & TS_USEDFPU)
clts();
load_gdt(&__get_cpu_var(host_gdt));
}
static void vmx_load_host_state(struct vcpu_vmx *vmx)
@ -1379,6 +1381,8 @@ static int hardware_enable(void *garbage)
ept_sync_global();
}
store_gdt(&__get_cpu_var(host_gdt));
return 0;
}