Re: [Qemu-devel] [PATCH] spapr: Only report host/guest IOMMU page size mismatches on KVM

[Thomas Huth <thuth@redhat.com>]

On 04.07.2017 15:54, David Gibson wrote:
> We print a warning if the spapr IOMMU isn't configured to support a page
> size matching the host page size backing RAM.  When that's the case we need
> more complex logic to translate VFIO mappings, which is slower.
> 
> But, it's not so slow that it would be at all noticeable against the
> general slowness of TCG.  So, only warn when using KVM.  This removes some
> noisy and unhelpful warnings from make check on hosts with page sizes
> which typically differ from those on POWER (e.g. Sparc).
> 
> Reported-by: Peter Maydell <peter.maydell@linaro.org>
> Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> ---
>  hw/ppc/spapr_pci.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
> index cc1588d..a52dcf8 100644
> --- a/hw/ppc/spapr_pci.c
> +++ b/hw/ppc/spapr_pci.c
> @@ -1745,7 +1745,8 @@ static void spapr_phb_realize(DeviceState *dev, Error **errp)
>      }
>  
>      /* DMA setup */
> -    if ((sphb->page_size_mask & qemu_getrampagesize()) == 0) {
> +    if (((sphb->page_size_mask & qemu_getrampagesize()) == 0)
> +        && kvm_enabled()) {

Since you've put me on CC: ... too much parenthesis for my taste ;-)

Apart from that,

Reviewed-by: Thomas Huth <thuth@redhat.com>