On Fri, Mar 03, 2017 at 05:32:57PM -0600, Michael Roth wrote: > In certain cases, such as PCI-passthrough with VFIO, we cannot offload > MMIO accesses to KVM unless the BAR alignment matches the host. This > patch, in conjunction with a separately submitted patch for SLOF > which allows for control of this via the device-tree, allows us to > set this alignment via QEMU. > > Cc: qemu-...@nongnu.org > Cc: Nikunj A Dadhania <nik...@linux.vnet.ibm.com> > Cc: David Gibson <da...@gibson.dropbear.id.au> > Cc: Alexey Kardashevskiy <a...@ozlabs.ru> > Signed-off-by: Michael Roth <mdr...@linux.vnet.ibm.com> > --- > v2: > * Keep natural alignment as the default in SLOF, only set DT prop if > different alignment is specified by QEMU (David)
Unfortunately, this has missed the cutoff for qemu-2.9.
I'm afraid I'm still not entirely clear on the rationale here.
Why do we need a variable parameter based on the host page size?
Couldn't we just have SLOF always align to something "big enough"
(64kiB, IIUC)?
> ---
> hw/ppc/spapr.c | 7 ++++++-
> hw/ppc/spapr_pci.c | 10 ++++++++++
> include/hw/pci-host/spapr.h | 1 +
> 3 files changed, 17 insertions(+), 1 deletion(-)
>
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 14192ac..ef8df35 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -3166,7 +3166,12 @@ DEFINE_SPAPR_MACHINE(2_9, "2.9", true);
> * pseries-2.8
> */
> #define SPAPR_COMPAT_2_8 \
> - HW_COMPAT_2_8
> + HW_COMPAT_2_8 \
> + { \
> + .driver = TYPE_SPAPR_PCI_HOST_BRIDGE, \
> + .property = "mem_bar_min_align", \
> + .value = "0", \
> + }, \
>
> static void spapr_machine_2_8_instance_options(MachineState *machine)
> {
> diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
> index 919d3c2..485d32d 100644
> --- a/hw/ppc/spapr_pci.c
> +++ b/hw/ppc/spapr_pci.c
> @@ -1664,6 +1664,10 @@ static void spapr_phb_realize(DeviceState *dev, Error
> **errp)
> return;
> }
>
> + if (sphb->mem_bar_min_align == (uint64_t)-1) {
> + sphb->mem_bar_min_align = qemu_real_host_page_size;
> + }
> +
> sphb->dtbusname = g_strdup_printf("pci@%" PRIx64, sphb->buid);
>
> namebuf = alloca(strlen(sphb->dtbusname) + 32);
> @@ -1858,6 +1862,8 @@ static Property spapr_phb_properties[] = {
> DEFINE_PROP_UINT32("numa_node", sPAPRPHBState, numa_node, -1),
> DEFINE_PROP_BOOL("pre-2.8-migration", sPAPRPHBState,
> pre_2_8_migration, false),
> + DEFINE_PROP_UINT64("mem_bar_min_align", sPAPRPHBState, mem_bar_min_align,
> + -1),
> DEFINE_PROP_END_OF_LIST(),
> };
>
> @@ -2228,6 +2234,10 @@ int spapr_populate_pci_dt(sPAPRPHBState *phb,
> if (ret) {
> return ret;
> }
> + if (phb->mem_bar_min_align) {
> + _FDT(fdt_setprop_cell(fdt, bus_off, "qemu,mem-bar-min-align",
> + phb->mem_bar_min_align));
> + }
>
> return 0;
> }
> diff --git a/include/hw/pci-host/spapr.h b/include/hw/pci-host/spapr.h
> index dfa7614..fa33346 100644
> --- a/include/hw/pci-host/spapr.h
> +++ b/include/hw/pci-host/spapr.h
> @@ -79,6 +79,7 @@ struct sPAPRPHBState {
> uint64_t dma64_win_addr;
>
> uint32_t numa_node;
> + uint64_t mem_bar_min_align;
>
> /* Fields for migration compatibility hacks */
> bool pre_2_8_migration;
--
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
signature.asc
Description: PGP signature
