Re: [Qemu-devel] [PATCH 21/26] Implement TCE translation for sPAPR VIO

[Anthony Liguori <anthony@codemonkey.ws>]

On 03/15/2011 11:56 PM, David Gibson wrote:
> From: Ben Herrenschmidt<benh@kernel.crashing.org>
>
> This patch implements the necessary infrastructure and hypercalls for
> sPAPR's TCE (Translation Control Entry) IOMMU mechanism.  This is necessary
> for all virtual IO devices which do DMA (i.e. nearly all of them).
>
> Signed-off-by: Ben Herrenschmidt<benh@kernel.crashing.org>
> Signed-off-by: David Gibson<dwg@au1.ibm.com>
> ---
>   hw/spapr.c     |    3 +-
>   hw/spapr_vio.c |  232 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>   hw/spapr_vio.h |   32 ++++++++
>   3 files changed, 266 insertions(+), 1 deletions(-)
>
> diff --git a/hw/spapr.c b/hw/spapr.c
> index e7f8864..a362889 100644
> --- a/hw/spapr.c
> +++ b/hw/spapr.c
> @@ -62,7 +62,8 @@ static void *spapr_create_fdt(int *fdt_size, ram_addr_t ramsize,
>       uint32_t start_prop = cpu_to_be32(initrd_base);
>       uint32_t end_prop = cpu_to_be32(initrd_base + initrd_size);
>       uint32_t pft_size_prop[] = {0, cpu_to_be32(hash_shift)};
> -    char hypertas_prop[] = "hcall-pft\0hcall-term\0hcall-dabr\0hcall-interrupt";
> +    char hypertas_prop[] = "hcall-pft\0hcall-term\0hcall-dabr\0hcall-interrupt"
> +        "\0hcall-tce";
>       uint32_t interrupt_server_ranges_prop[] = {0, cpu_to_be32(smp_cpus)};
>       int i;
>       char *modelname;
> diff --git a/hw/spapr_vio.c b/hw/spapr_vio.c
> index 45edd94..37cf51e 100644
> --- a/hw/spapr_vio.c
> +++ b/hw/spapr_vio.c
> @@ -37,6 +37,7 @@
>   #endif /* CONFIG_FDT */
>
>   /* #define DEBUG_SPAPR */
> +/* #define DEBUG_TCE */
>
>   #ifdef DEBUG_SPAPR
>   #define dprintf(fmt, ...) \
> @@ -114,6 +115,28 @@ static int vio_make_devnode(VIOsPAPRDevice *dev,
>               return ret;
>       }
>
> +    if (dev->rtce_window_size) {
> +        uint32_t dma_prop[] = {cpu_to_be32(dev->reg),
> +                               0, 0,
> +                               0, cpu_to_be32(dev->rtce_window_size)};
> +
> +        ret = fdt_setprop_cell(fdt, node_off, "ibm,#dma-address-cells", 2);
> +        if (ret<  0) {
> +            return ret;
> +        }
> +
> +        ret = fdt_setprop_cell(fdt, node_off, "ibm,#dma-size-cells", 2);
> +        if (ret<  0) {
> +            return ret;
> +        }
> +
> +        ret = fdt_setprop(fdt, node_off, "ibm,my-dma-window", dma_prop,
> +                          sizeof(dma_prop));
> +        if (ret<  0) {
> +            return ret;
> +        }
> +    }
> +
>       if (info->devnode) {
>           ret = (info->devnode)(dev, fdt, node_off);
>           if (ret<  0) {
> @@ -125,6 +148,210 @@ static int vio_make_devnode(VIOsPAPRDevice *dev,
>   }
>   #endif /* CONFIG_FDT */
>
> +/*
> + * RTCE handling
> + */
> +
> +static void rtce_init(VIOsPAPRDevice *dev)
> +{
> +    size_t size = (dev->rtce_window_size>>  SPAPR_VIO_TCE_PAGE_SHIFT)
> +        * sizeof(VIOsPAPR_RTCE);
> +
> +    if (size) {
> +        dev->rtce_table = qemu_mallocz(size);
> +    }
> +}
> +
> +static target_ulong h_put_tce(CPUState *env, sPAPREnvironment *spapr,
> +                              target_ulong opcode, target_ulong *args)
> +{
> +    target_ulong liobn = args[0];
> +    target_ulong ioba = args[1];
> +    target_ulong tce = args[2];
> +    VIOsPAPRDevice *dev = spapr_vio_find_by_reg(spapr->vio_bus, liobn);
> +    VIOsPAPR_RTCE *rtce;
> +
> +    if (!dev) {
> +        fprintf(stderr, "spapr_vio_put_tce on non-existent LIOBN "
> +                TARGET_FMT_lx "\n",
> +                liobn);

You generally want to avoid guest triggered fprintfs as it can be 
exploited in scenarios where qemu's stdout is logged to disk (libvirt).  
We usually wrap this in a DPRINTF() of some sort.

Regards,

Anthony Liguori