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").
This is a use case in communication between a userspace application
in the guest and the introspection application in dom0.
Signed-off-by: Alexandru Isaila <aisa...@bitdefender.com>
---
Changes since V1:
- Added Fallthrough check on mode == 2
---
xen/arch/x86/hvm/hypercall.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/xen/arch/x86/hvm/hypercall.c b/xen/arch/x86/hvm/hypercall.c
index e7238ce..1c067c3 100644
--- a/xen/arch/x86/hvm/hypercall.c
+++ b/xen/arch/x86/hvm/hypercall.c
@@ -152,9 +152,15 @@ int hvm_hypercall(struct cpu_user_regs *regs)
{
case 8:
eax = regs->rax;
+ if ( eax == __HYPERVISOR_hvm_op &&
+ regs->rdi == HVMOP_guest_request_vm_event )
+ break;
/* Fallthrough to permission check. */
case 4:
case 2:
+ if ( mode != 8 && eax == __HYPERVISOR_hvm_op &&
+ regs->ebx == HVMOP_guest_request_vm_event )
+ break;
if ( unlikely(hvm_get_cpl(curr)) )
{
default:
--
2.7.4
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