Re: [Xen-devel] [PATCH 6/6] Introduce domain flag (dont_flush_iotlb) to avoid unnecessary iotlb flush.

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 04.11.11 at 11:38, Jean Guyader <jean.guyader@xxxxxxxxxxxxx> wrote:

> Add a domain level flag that will be check by the iommu low level code
> to skip iotlb flush. iommu_iotlb_flush has to be called explicitly.
> 
> Signed-off-by: Jean Guyader <jean.guyader@xxxxxxxxxxxxx>
> ---
>  xen/arch/x86/mm.c                   |   12 +++++++++++-
>  xen/drivers/passthrough/iommu.c     |    6 ++++++
>  xen/drivers/passthrough/vtd/iommu.c |    6 ++++--
>  xen/include/xen/sched.h             |    1 +
>  4 files changed, 22 insertions(+), 3 deletions(-)

Neither the patch nor its description make clear what lock is used
to protect this flag from having an effect on other but the current
vCPU of the guest in question - I doubt that all other relevant code
paths indeed use domain_lock().

Jan


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