Re: [PATCH v3 4/8] s390/airq: use DMA memory for adapter interrupts

Cornelia Huck
2019-06-03T15:27:40Z

On Wed, 29 May 2019 14:26:53 +0200
Michael Mueller <mimu@linux.ibm.com> wrote:

> From: Halil Pasic <pasic@linux.ibm.com>
>
> 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 by
> replacing the kmem_cache with a dma_cache and kalloc() with
> cio_dma_zalloc().
>
> Signed-off-by: Halil Pasic <pasic@linux.ibm.com>
> Reviewed-by: Sebastian Ott <sebott@linux.ibm.com>
> Signed-off-by: Michael Mueller <mimu@linux.ibm.com>
> ---
> arch/s390/include/asm/airq.h | 2 ++
> drivers/s390/cio/airq.c | 32 ++++++++++++++++++++------------
> drivers/s390/cio/cio.h | 2 ++
> drivers/s390/cio/css.c | 1 +
> 4 files changed, 25 insertions(+), 12 deletions(-)

Apologies if that already has been answered (and I missed it in my mail
pile...), but two things had come to my mind previously:

- CHSC... does anything need to be done there? Last time I asked:
"Anyway, css_bus_init() uses some chscs
early (before cio_dma_pool_init), so we could not use the pools
there, even if we wanted to. Do chsc commands either work, or else
fail benignly on a protected virt guest?"
- PCI indicators... does this interact with any dma configuration on
the pci device? (I know pci is not supported yet, and I don't really
expect any problems.)