From: Tamas K Lengyel Date: Mon, 13 May 2019 07:55:59 +0000 (+0200) Subject: x86/vmx: correctly gather gs_shadow value for current vCPU X-Git-Tag: archive/raspbian/4.14.0+80-gd101b417b7-1+rpi1^2~63^2~2310 X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=f69fc1c2f36e8a74ba54c9c8fa5c904ea1ad319e;p=xen.git x86/vmx: correctly gather gs_shadow value for current vCPU Currently the gs_shadow value is only cached when the vCPU is being scheduled out by Xen. Reporting this (usually) stale value through vm_event is incorrect, since it doesn't represent the actual state of the vCPU at the time the event was recorded. This prevents vm_event subscribers from correctly finding kernel structures in the guest when it is trapped while in ring3. Refresh shadow_gs value when the context being saved is for the current vCPU. Signed-off-by: Tamas K Lengyel Acked-by: Razvan Cojocaru Reviewed-by: Andrew Cooper Acked-by: Kevin Tian --- diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c index 283eb7b34d..6475f5b019 100644 --- a/xen/arch/x86/hvm/vmx/vmx.c +++ b/xen/arch/x86/hvm/vmx/vmx.c @@ -779,12 +779,18 @@ static void vmx_load_cpu_state(struct vcpu *v, struct hvm_hw_cpu *data) static void vmx_save_vmcs_ctxt(struct vcpu *v, struct hvm_hw_cpu *ctxt) { + if ( v == current ) + vmx_save_guest_msrs(v); + vmx_save_cpu_state(v, ctxt); vmx_vmcs_save(v, ctxt); } static int vmx_load_vmcs_ctxt(struct vcpu *v, struct hvm_hw_cpu *ctxt) { + /* Not currently safe to use in current context. */ + ASSERT(v != current); + vmx_load_cpu_state(v, ctxt); if ( vmx_vmcs_restore(v, ctxt) )