Re: [Xen-devel] __HYPERVISOR_COMPAT_VIRT_START for HVM guest with PV drivers

[Chuck Anderson <chuck.anderson@xxxxxxxxxx>]

Signed-off-by: Chuck Anderson <chuck.anderson@xxxxxxxxxx>

I booted a 3.4.0 based hypervisor with changeset 20101 applied and verified that it resolved the problem.
Chuck

Keir Fraser wrote:

On 20/08/2009 17:27, "Keir Fraser" <keir.fraser@xxxxxxxxxxxxx> wrote:

  

Do the guest virtual addresses passed by a hypervisor call on a 32-bit
HVM with PV drivers guest to a 64-bit hypervisor need to lie below
__HYPERVISOR_COMPAT_VIRT_START?  Both HVM and PVM domains have their
hv_compat_vstart set to __HYPERVISOR_COMPAT_VIRT_START.  The
hypervisor's compat layer is causing the balloon driver's
HYPERVISOR_memory_op(XENMEM_decrease_reservation, &reservation)
hypervisor call to error out in xen/common/compat/memory.c
compat_memory_op(), compat_handle_ok(), because the PVHVM guest's
extent_start lies above __HYPERVISOR_COMPAT_VIRT_START.  The following
patch appears to fix the problem but I want to make sure it is fixing
the real bug:
      

Yeah, you pretty much have it figured. I may just clean up for style (I
think an extra macro for this is a bit pointless), but the patch is
fundamentally good.
    

Take a look at xen-unstable.hg:20101

 -- Keir


  

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