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 <rcojoc...@bitdefender.com>
Reviewed-by: Andrew Cooper <andrew.coop...@citirx.com>
---
Changes since V2:
- Updated the if() condition as recommended by Andrew Cooper.
- Added Andrew Cooper's Reviewed-by.
---
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 0954b59..d367099 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,
--
1.9.1
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