From 972523bcefe215b46ffd74fa08b8199cec2fde05 Mon Sep 17 00:00:00 2001 From: Andrew Cooper Date: Mon, 11 Apr 2016 10:03:55 +0100 Subject: [PATCH] x86/pv: Correctly fold vIOPL back into vcpu_guest_context c/s f71ecb6 "x86: introduce a new VMASSIST for architectural behaviour of iopl" shifted the vcpu iopl field by 12, but didn't update the logic which reconstructs the guests eflags for migration. Existing guest kernels set a vIOPL of 1, to prevent them from faulting when accessing IO ports. This bug manifests as a crash after migrate, as the vIOPL reverts back to the default of 0, and the guest suffers an unexpected #GP fault. Signed-off-by: Andrew Cooper Reviewed-by: Wei Liu Tested-by: Boris Ostrovsky --- xen/arch/x86/domctl.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/xen/arch/x86/domctl.c b/xen/arch/x86/domctl.c index cba1e378d5..6e709cb691 100644 --- a/xen/arch/x86/domctl.c +++ b/xen/arch/x86/domctl.c @@ -1512,7 +1512,7 @@ void arch_get_info_guest(struct vcpu *v, vcpu_guest_context_u c) /* IOPL privileges are virtualised: merge back into returned eflags. */ BUG_ON((c(user_regs.eflags) & X86_EFLAGS_IOPL) != 0); - c(user_regs.eflags |= v->arch.pv_vcpu.iopl << 12); + c(user_regs.eflags |= v->arch.pv_vcpu.iopl); if ( !compat ) { -- 2.30.2