Re: [PATCH 07/10] s390/airq: use DMA memory for adapter interrupts

Cornelia Huck
2019-05-09T11:37:01Z

On Fri, 26 Apr 2019 20:32:42 +0200
Halil Pasic <pasic@linux.ibm.com> wrote:

> Protected virtualization guests have to use shared pages for airq
> notifier bit vectors, because hypervisor needs to write these bits.
>
> Let us make sure we allocate DMA memory for the notifier bit vectors.
>
> Signed-off-by: Halil Pasic <pasic@linux.ibm.com>
> ---
> arch/s390/include/asm/airq.h | 2 ++
> drivers/s390/cio/airq.c | 18 ++++++++++++++----
> 2 files changed, 16 insertions(+), 4 deletions(-)

As an aside, there are some other devices that use adapter interrupts
as well (pci, ap, qdio). How does that interact with their needs? Do
they continue to work on non-protected virt guests (kvm or z/VM), and
can they be accommodated if support for them on protected guests is
added in the future?

(For some of the indicator bit handling, I suspect millicode takes care
of it anyway, but at least for pci, there's some hypervisor action to
be aware of.)

Also, as another aside, has this been tested with a regular guest under
tcg as well? If not, can you provide a branch for quick verification
somewhere?