[Qemu-devel] VMport patch

[Qemu-devel] VMport patch

[Filip Navara]

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Hello,

the current version of QEMU emulates the VMware backdoor I/O port and it
works quite well. Unfortunately it doesn't emulate the VMware behavior of
ignoring the I/O permissions when accessing this special port. The attached
patch corrects it. It's important to ignore the permissions, so that user
mode VMware tools can communicate to the backdoor.

Best regards,
Filip Navara

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--- target-i386/helper.c	26 Jun 2007 08:35:18 -0000	1.84
+++ target-i386/helper.c	20 Jan 2008 18:33:33 -0000
@@ -486,7 +486,9 @@
 static inline void check_io(int addr, int size)
 {
     int io_offset, val, mask;
-    
+    /* VMware backdoor I/O port ignores priviledge control */
+    if (addr == 0x5658)
+        return;   
     /* TSS must be a valid 32 bit one */
     if (!(env->tr.flags & DESC_P_MASK) ||
         ((env->tr.flags >> DESC_TYPE_SHIFT) & 0xf) != 9 ||

Re: [Qemu-devel] VMport patch

[Anthony Liguori]

Filip Navara wrote:
> Hello,
>
> the current version of QEMU emulates the VMware backdoor I/O port and 
> it works quite well. Unfortunately it doesn't emulate the VMware 
> behavior of ignoring the I/O permissions when accessing this special 
> port. The attached patch corrects it. It's important to ignore the 
> permissions, so that user mode VMware tools can communicate to the 
> backdoor. =

I really dislike that VMware relies on this.  It's very hard to 
implement in kqemu or KVM.  I think it would be better to modify 
open-vm-tools than to modify QEMU.

Regards,

Anthony Liguori

> Best regards,
> Filip Navara