Re: [Qemu-devel] [RFC PATCH v2 07/13] spapr_rtas: Add Dynamic DMA windows (DDW) RTAS calls support

[Alexander Graf <agraf@suse.de>]

On 15.08.14 12:12, Alexey Kardashevskiy wrote:
> This adds support for Dynamic DMA Windows (DDW) option defined by
> the SPAPR specification which allows to have additional DMA window(s)
> which can support page sizes other than 4K.
> 
> The existing implementation of DDW in the guest tries to create one huge
> DMA window with 64K or 16MB pages and map the entire guest RAM to. If it
> succeeds, the guest switches to dma_direct_ops and never calls
> TCE hypercalls (H_PUT_TCE,...) again. This enables VFIO devices to use
> the entire RAM and not waste time on map/unmap.
> 
> This adds 4 RTAS handlers:
> * ibm,query-pe-dma-window
> * ibm,create-pe-dma-window
> * ibm,remove-pe-dma-window
> * ibm,reset-pe-dma-window
> These are registered from type_init() callback.
> 
> These RTAS handlers are implemented in a separate file to avoid polluting
> spapr_iommu.c with PHB.
> 
> Since no PHB class implements new callback in this patch, no functional
> change is expected.
> 
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> ---
> Changes:
> v2:
> * double loop squashed to spapr_iommu_fixmask() helper
> * added @ddw_num counter to PHB, it is used to generate LIOBN for new
> window; it is reset on ddw-reset event
> * added ULL to constants used in shift operations
> * rtas_ibm_reset_pe_dma_window() and rtas_ibm_remove_pe_dma_window()
> do not remove windows anymore, the PHB callback has to as it will reuse
> the same code in case of guest reboot as well
> ---
>  hw/ppc/Makefile.objs        |   3 +
>  hw/ppc/spapr_pci.c          |   3 +-
>  hw/ppc/spapr_rtas_ddw.c     | 283 ++++++++++++++++++++++++++++++++++++++++++++
>  include/hw/pci-host/spapr.h |  19 +++
>  include/hw/ppc/spapr.h      |   6 +-
>  trace-events                |   4 +
>  6 files changed, 316 insertions(+), 2 deletions(-)
>  create mode 100644 hw/ppc/spapr_rtas_ddw.c
> 
> diff --git a/hw/ppc/Makefile.objs b/hw/ppc/Makefile.objs
> index edd44d0..9773294 100644
> --- a/hw/ppc/Makefile.objs
> +++ b/hw/ppc/Makefile.objs
> @@ -7,6 +7,9 @@ obj-$(CONFIG_PSERIES) += spapr_pci.o
>  ifeq ($(CONFIG_PCI)$(CONFIG_PSERIES)$(CONFIG_LINUX), yyy)
>  obj-y += spapr_pci_vfio.o
>  endif
> +ifeq ($(CONFIG_PCI)$(CONFIG_PSERIES), yy)
> +obj-y += spapr_rtas_ddw.o
> +endif
>  # PowerPC 4xx boards
>  obj-y += ppc405_boards.o ppc4xx_devs.o ppc405_uc.o ppc440_bamboo.o
>  obj-y += ppc4xx_pci.o
> diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
> index aa20c36..9b03d0d 100644
> --- a/hw/ppc/spapr_pci.c
> +++ b/hw/ppc/spapr_pci.c
> @@ -759,7 +759,7 @@ static int spapr_pci_post_load(void *opaque, int version_id)
>  
>  static const VMStateDescription vmstate_spapr_pci = {
>      .name = "spapr_pci",
> -    .version_id = 2,
> +    .version_id = 3,
>      .minimum_version_id = 2,
>      .pre_save = spapr_pci_pre_save,
>      .post_load = spapr_pci_post_load,
> @@ -775,6 +775,7 @@ static const VMStateDescription vmstate_spapr_pci = {
>          VMSTATE_INT32(msi_devs_num, sPAPRPHBState),
>          VMSTATE_STRUCT_VARRAY_ALLOC(msi_devs, sPAPRPHBState, msi_devs_num, 0,
>                                      vmstate_spapr_pci_msi, spapr_pci_msi_mig),
> +        VMSTATE_UINT32_V(ddw_num, sPAPRPHBState, 3),
>          VMSTATE_END_OF_LIST()
>      },
>  };
> diff --git a/hw/ppc/spapr_rtas_ddw.c b/hw/ppc/spapr_rtas_ddw.c
> new file mode 100644
> index 0000000..2b5376a
> --- /dev/null
> +++ b/hw/ppc/spapr_rtas_ddw.c
> @@ -0,0 +1,283 @@
> +/*
> + * QEMU sPAPR Dynamic DMA windows support
> + *
> + * Copyright (c) 2014 Alexey Kardashevskiy, IBM Corporation.
> + *
> + *  This program is free software; you can redistribute it and/or modify
> + *  it under the terms of the GNU General Public License as published by
> + *  the Free Software Foundation; either version 2 of the License,
> + *  or (at your option) any later version.
> + *
> + *  This program is distributed in the hope that it will be useful,
> + *  but WITHOUT ANY WARRANTY; without even the implied warranty of
> + *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + *  GNU General Public License for more details.
> + *
> + *  You should have received a copy of the GNU General Public License
> + *  along with this program; if not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#include "hw/ppc/spapr.h"
> +#include "hw/pci-host/spapr.h"
> +#include "trace.h"
> +
> +static uint32_t spapr_iommu_fixmask(struct ppc_one_seg_page_size *sps,
> +                                    uint32_t query_mask)
> +{
> +    int i, j;
> +    uint32_t mask = 0;
> +    const struct { int shift; uint32_t mask; } masks[] = {
> +        { 12, DDW_PGSIZE_4K },
> +        { 16, DDW_PGSIZE_64K },
> +        { 24, DDW_PGSIZE_16M },
> +        { 25, DDW_PGSIZE_32M },
> +        { 26, DDW_PGSIZE_64M },
> +        { 27, DDW_PGSIZE_128M },
> +        { 28, DDW_PGSIZE_256M },
> +        { 34, DDW_PGSIZE_16G },
> +    };
> +
> +    for (i = 0; i < PPC_PAGE_SIZES_MAX_SZ; i++) {
> +        for (j = 0; j < ARRAY_SIZE(masks); ++j) {
> +            if ((sps[i].page_shift == masks[j].shift) &&
> +                    (query_mask & masks[j].mask)) {
> +                mask |= masks[j].mask;
> +            }
> +        }
> +    }
> +
> +    return mask;
> +}
> +
> +static void rtas_ibm_query_pe_dma_window(PowerPCCPU *cpu,
> +                                         sPAPREnvironment *spapr,
> +                                         uint32_t token, uint32_t nargs,
> +                                         target_ulong args,
> +                                         uint32_t nret, target_ulong rets)
> +{
> +    CPUPPCState *env = &cpu->env;
> +    sPAPRPHBState *sphb;
> +    sPAPRPHBClass *spc;
> +    uint64_t buid;
> +    uint32_t addr, pgmask = 0;
> +    uint32_t windows_available = 0, page_size_mask = 0;
> +    long ret;
> +
> +    if ((nargs != 3) || (nret != 5)) {
> +        goto param_error_exit;
> +    }
> +
> +    buid = ((uint64_t)rtas_ld(args, 1) << 32) | rtas_ld(args, 2);
> +    addr = rtas_ld(args, 0);
> +    sphb = spapr_pci_find_phb(spapr, buid);
> +    if (!sphb) {
> +        goto param_error_exit;
> +    }
> +
> +    spc = SPAPR_PCI_HOST_BRIDGE_GET_CLASS(sphb);
> +    if (!spc->ddw_query) {
> +        goto hw_error_exit;
> +    }
> +
> +    ret = spc->ddw_query(sphb, &windows_available, &page_size_mask);
> +    trace_spapr_iommu_ddw_query(buid, addr, windows_available,
> +                                page_size_mask, pgmask, ret);
> +    if (ret) {
> +        goto hw_error_exit;
> +    }
> +
> +    /* Work out supported page masks */
> +    pgmask = spapr_iommu_fixmask(env->sps.sps, page_size_mask);
> +
> +    rtas_st(rets, 0, RTAS_OUT_SUCCESS);
> +    rtas_st(rets, 1, windows_available);
> +
> +    /*
> +     * This is "Largest contiguous block of TCEs allocated specifically
> +     * for (that is, are reserved for) this PE".
> +     * Return the maximum number as all RAM was in 4K pages.
> +     */
> +    rtas_st(rets, 2, ram_size >> SPAPR_TCE_PAGE_SHIFT);
> +    rtas_st(rets, 3, pgmask);
> +    rtas_st(rets, 4, pgmask); /* DMA migration mask */
> +    return;
> +
> +hw_error_exit:
> +    rtas_st(rets, 0, RTAS_OUT_HW_ERROR);
> +    return;
> +
> +param_error_exit:
> +    rtas_st(rets, 0, RTAS_OUT_PARAM_ERROR);
> +}
> +
> +static void rtas_ibm_create_pe_dma_window(PowerPCCPU *cpu,
> +                                          sPAPREnvironment *spapr,
> +                                          uint32_t token, uint32_t nargs,
> +                                          target_ulong args,
> +                                          uint32_t nret, target_ulong rets)
> +{
> +    sPAPRPHBState *sphb;
> +    sPAPRPHBClass *spc;
> +    sPAPRTCETable *tcet = NULL;
> +    uint32_t addr, page_shift, window_shift, liobn;
> +    uint64_t buid;
> +    long ret;
> +
> +    if ((nargs != 5) || (nret != 4)) {
> +        goto param_error_exit;
> +    }
> +
> +    buid = ((uint64_t)rtas_ld(args, 1) << 32) | rtas_ld(args, 2);
> +    addr = rtas_ld(args, 0);
> +    sphb = spapr_pci_find_phb(spapr, buid);
> +    if (!sphb) {
> +        goto param_error_exit;
> +    }
> +
> +    spc = SPAPR_PCI_HOST_BRIDGE_GET_CLASS(sphb);
> +    if (!spc->ddw_create) {
> +        goto hw_error_exit;
> +    }
> +
> +    page_shift = rtas_ld(args, 3);
> +    window_shift = rtas_ld(args, 4);
> +    /* Default 32bit window#0 is always there so +1 */
> +    liobn = SPAPR_PCI_LIOBN(sphb->index, sphb->ddw_num + 1);

What if you just initialize ddw_num to 1 on init?


Alex