[Xen-devel] [PATCH RFC] x86/xen: Return error for xc_hvm_inject_trap() with pending events

[Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx>]

xc_hvm_inject_trap() sets v->arch.hvm_vcpu.inject_trap.vector,
which is then checked in hvm_do_resume(), and if != -1, a trap
is injected, regardless of whether vmx_idtv_reinject() has written
VM_ENTRY_INTR_INFO directly. If that's the case, the toolstack
injected interrupt will overwrite the reinjected one, which will
get lost forever. This patch returns -EBUSY not only if
v->arch.hvm_vcpu.inject_trap.vector != -1, but also if
hvm_event_pending(v). hvm_event_pending() has also been modified
to be able to run on a VCPU which is not current.

Signed-off-by: Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx>
---
 xen/arch/x86/hvm/hvm.c     | 2 +-
 xen/arch/x86/hvm/vmx/vmx.c | 3 ++-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 704fd64..cf01ae4 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -5938,7 +5938,7 @@ long do_hvm_op(unsigned long op, 
XEN_GUEST_HANDLE_PARAM(void) arg)
         if ( tr.vcpuid >= d->max_vcpus || (v = d->vcpu[tr.vcpuid]) == NULL )
             goto injtrap_fail;
         
-        if ( v->arch.hvm_vcpu.inject_trap.vector != -1 )
+        if ( v->arch.hvm_vcpu.inject_trap.vector != -1 || hvm_event_pending(v) 
)
             rc = -EBUSY;
         else 
         {
diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index 9a8f694..f50a593 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -1790,8 +1790,9 @@ static int vmx_event_pending(struct vcpu *v)
 {
     unsigned long intr_info;
 
-    ASSERT(v == current);
+    vmx_vmcs_enter(v);
     __vmread(VM_ENTRY_INTR_INFO, &intr_info);
+    vmx_vmcs_exit(v);
 
     return intr_info & INTR_INFO_VALID_MASK;
 }
-- 
1.9.1


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