| Message ID | 1470380899-11382-1-git-send-email-rcojocaru@bitdefender.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
>>> On 05.08.16 at 09:08, <rcojocaru@bitdefender.com> wrote: > --- 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; For one, Coverity will choke on there not being a fall-through annotation. And then the resulting fall-through behavior is now wrong: You don't want the 64-bit case to also do the 16-/32-bit check. Finally, as indicated before, such a special casing model doesn't scale well, i.e. as soon as further exception would get suggested the code would quickly become hard to understand and maintain (as is already being supported by the issue pointed out above, addressing of which will likely further convolute this code). Jan
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) ) {
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@bitdefender.com> --- xen/arch/x86/hvm/hvm.c | 6 ++++++ 1 file changed, 6 insertions(+)