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

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

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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