On Fri, Feb 09, 2018 at 06:55:03PM +1100, Alexey Kardashevskiy wrote: > This adds a possibility for the platform to tell VFIO not to emulate MSIX > so MMIO memory regions do not get split into chunks in flatview and > the entire page can be registered as a KVM memory slot and make direct > MMIO access possible for the guest. > > This enables the entire MSIX BAR mapping to the guest for the pseries > platform in order to achieve the maximum MMIO preformance for certain > devices. > > Tested on: > LSI Logic / Symbios Logic SAS3008 PCI-Express Fusion-MPT SAS-3 (rev 02) > > Signed-off-by: Alexey Kardashevskiy <a...@ozlabs.ru>
I still think having the property on the machine is an uglier option
than having it on the device, but Alex didn't like that, so I'll roll
with it.
Reivewed-by: David Gibson <da...@gibson.dropbear.id.au>
> ---
>
> Need to split this in two?
> ---
> hw/ppc/spapr.c | 7 +++++++
> hw/vfio/pci.c | 13 +++++++++++++
> 2 files changed, 20 insertions(+)
>
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index eb3e1a7..14d8ecb 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -2855,6 +2855,11 @@ static void spapr_set_modern_hotplug_events(Object
> *obj, bool value,
> spapr->use_hotplug_event_source = value;
> }
>
> +static bool spapr_get_msix_emulation(Object *obj, Error **errp)
> +{
> + return true;
> +}
> +
> static char *spapr_get_resize_hpt(Object *obj, Error **errp)
> {
> sPAPRMachineState *spapr = SPAPR_MACHINE(obj);
> @@ -2936,6 +2941,8 @@ static void spapr_instance_init(Object *obj)
> object_property_set_description(obj, "vsmt",
> "Virtual SMT: KVM behaves as if this
> were"
> " the host's SMT mode", &error_abort);
> + object_property_add_bool(obj, "vfio-no-msix-emulation",
> + spapr_get_msix_emulation, NULL, NULL);
> }
>
> static void spapr_machine_finalizefn(Object *obj)
> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
> index ae9098d..4a03085 100644
> --- a/hw/vfio/pci.c
> +++ b/hw/vfio/pci.c
> @@ -1580,6 +1580,19 @@ static int vfio_msix_setup(VFIOPCIDevice *vdev, int
> pos, Error **errp)
> */
> memory_region_set_enabled(&vdev->pdev.msix_pba_mmio, false);
>
> + /*
> + * The emulated machine may provide a paravirt interface for MSIX setup
> + * so it is not strictly necessary to emulate MSIX here. This becomes
> + * helpful when frequently accessed MMIO registers are located in
> + * subpages adjacent to the MSIX table but the MSIX data containing page
> + * cannot be mapped because of a host page size bigger than the MSIX
> table
> + * alignment.
> + */
> + if (object_property_get_bool(OBJECT(qdev_get_machine()),
> + "vfio-no-msix-emulation", NULL)) {
> + memory_region_set_enabled(&vdev->pdev.msix_table_mmio, false);
> + }
> +
> return 0;
> }
>
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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