From ffc109c28a6a4cb5047df82b1d18ad7a13d3e247 Mon Sep 17 00:00:00 2001 From: Avi Kivity Date: Thu, 28 Oct 2010 16:48:12 -0200 Subject: [PATCH] KVM: VMX: Fix host GDT.LIMIT corruption commit 3444d7da1839b851eefedd372978d8a982316c36 upstream. 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 Signed-off-by: Marcelo Tosatti Signed-off-by: Greg Kroah-Hartman --- arch/x86/kvm/vmx.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 6a28d5d95e8f..1850cb054d12 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -130,6 +130,7 @@ static u64 construct_eptp(unsigned long root_hpa); 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; @@ -690,6 +691,7 @@ static void __vmx_load_host_state(struct vcpu_vmx *vmx) save_msrs(vmx->guest_msrs, vmx->save_nmsrs); load_msrs(vmx->host_msrs, vmx->save_nmsrs); reload_host_efer(vmx); + load_gdt(&__get_cpu_var(host_gdt)); } static void vmx_load_host_state(struct vcpu_vmx *vmx) @@ -1176,6 +1178,8 @@ static void hardware_enable(void *garbage) asm volatile (ASM_VMX_VMXON_RAX : : "a"(&phys_addr), "m"(phys_addr) : "memory", "cc"); + + store_gdt(&__get_cpu_var(host_gdt)); } static void vmclear_local_vcpus(void) -- 2.39.5