[Xen-devel] [PATCH] x86/hvm: Allow guest_request vm_events coming from userspace

[Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx>]

Allow guest userspace code to request that a vm_event be sent out
via VMCALL. This functionality seems to be handy for a number of
Xen developers, as stated on the mailing list (thread "[Xen-devel]
HVMOP_guest_request_vm_event only works from guest in ring0").

Signed-off-by: Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx>
---
 xen/arch/x86/hvm/hvm.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 202866a..2d38936 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -5349,8 +5349,14 @@ int hvm_do_hypercall(struct cpu_user_regs *regs)
     switch ( mode )
     {
     case 8:        
+        if ( eax == __HYPERVISOR_hvm_op &&
+             regs->rdi == HVMOP_guest_request_vm_event )
+            break;
     case 4:
     case 2:
+        if ( eax == __HYPERVISOR_hvm_op &&
+             regs->_ebx == HVMOP_guest_request_vm_event )
+            break;
         hvm_get_segment_register(curr, x86_seg_ss, &sreg);
         if ( unlikely(sreg.attr.fields.dpl) )
         {
-- 
1.9.1


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