From 446155d3d15dac0969dd4fa2fdd95e7693b905ec Mon Sep 17 00:00:00 2001 From: Tamas K Lengyel Date: Tue, 4 Jun 2019 15:50:37 +0200 Subject: [PATCH] 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 master commit: f69fc1c2f36e8a74ba54c9c8fa5c904ea1ad319e master date: 2019-05-13 09:55:59 +0200 --- xen/arch/x86/hvm/vmx/vmx.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c index 2896d272b1..fa1e0309c7 100644 --- a/xen/arch/x86/hvm/vmx/vmx.c +++ b/xen/arch/x86/hvm/vmx/vmx.c @@ -901,12 +901,18 @@ 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) ) -- 2.39.5