From fdfd56453db7c303c8c82531b33401f40700a85e Mon Sep 17 00:00:00 2001 From: Razvan Cojocaru Date: Wed, 4 May 2016 09:42:06 +0200 Subject: [PATCH] x86/monitor: disallow setting mem_access_emulate_each_rep when vm_event is NULL It is meaningless (and potentially dangerous - see hvmemul_virtual_to_linear()) to set mem_access_emulate_each_rep before xc_monitor_enable() (which allocates vcpu->arch.vm_event) has been called, so return an error from the XEN_DOMCTL_MONITOR_OP_EMULATE_EACH_REP hypercall when that is the case. Signed-off-by: Razvan Cojocaru Reviewed-by: Andrew Cooper Release-acked-by: Wei Liu Acked-by: Tamas K Lengyel --- xen/include/asm-x86/monitor.h | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git a/xen/include/asm-x86/monitor.h b/xen/include/asm-x86/monitor.h index 0954b5904e..d367099cbb 100644 --- a/xen/include/asm-x86/monitor.h +++ b/xen/include/asm-x86/monitor.h @@ -32,19 +32,29 @@ static inline int arch_monitor_domctl_op(struct domain *d, struct xen_domctl_monitor_op *mop) { + int rc = 0; + switch ( mop->op ) { case XEN_DOMCTL_MONITOR_OP_EMULATE_EACH_REP: domain_pause(d); - d->arch.mem_access_emulate_each_rep = !!mop->event; + /* + * Enabling mem_access_emulate_each_rep without a vm_event subscriber + * is meaningless. + */ + if ( d->max_vcpus && d->vcpu[0] && d->vcpu[0]->arch.vm_event ) + d->arch.mem_access_emulate_each_rep = !!mop->event; + else + rc = -EINVAL; + domain_unpause(d); break; default: - return -EOPNOTSUPP; + rc = -EOPNOTSUPP; } - return 0; + return rc; } int arch_monitor_domctl_event(struct domain *d, -- 2.30.2