Re: [Qemu-devel] [RFC PATCH qemu v2] ppc/spapr: Receive and store device tree blob from SLOF

[Alexey Kardashevskiy <aik@ozlabs.ru>]

On 03/10/17 16:17, Alexey Kardashevskiy wrote:
> SLOF receives a device tree and updates it with various properties
> before switching to the guest kernel and QEMU is not aware of any changes
> made by SLOF. Since there is no real RTAS and QEMU implements it,
> it makes sense to pass the SLOF device tree to QEMU so the latter could
> implement RTAS related tasks better.
> 
> Specifially, now QEMU can find out the actual XICS phandle (for PHB
> hotplug) and the RTAS linux,rtas-entry/base properties (for firmware
> assisted NMI - FWNMI).
> 
> This stores the initial DT blob in the sPAPR machine and replaces it
> in the KVMPPC_H_UPDATE_DT (new private hypercall) handler.
> 
> This implements a very basic validity check of the new blob - magic and
> size are checked; the new blob size should not increase more than twice.
> 
> This requires SLOF update: "fdt: Pass the resulting device tree to QEMU".
> 
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> ---
> 
> I could store just a size of the QEMU's blob, or a tree, not sure
> which one makes more sense here.
> 
> This allows up to 2 times blob increase. Not 1.5 just to avoid
> float/double, just looks a bit ugly imho.
> ---
>  include/hw/ppc/spapr.h |  4 +++-
>  hw/ppc/spapr.c         |  4 +++-
>  hw/ppc/spapr_hcall.c   | 33 +++++++++++++++++++++++++++++++++
>  hw/ppc/trace-events    |  2 ++
>  4 files changed, 41 insertions(+), 2 deletions(-)
> 
> diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> index a805b817a5..09f3a54dc2 100644
> --- a/include/hw/ppc/spapr.h
> +++ b/include/hw/ppc/spapr.h
> @@ -92,6 +92,7 @@ struct sPAPRMachineState {
>      int vrma_adjust;
>      ssize_t rtas_size;
>      void *rtas_blob;
> +    void *fdt_blob;
>      long kernel_size;
>      bool kernel_le;
>      uint32_t initrd_base;
> @@ -400,7 +401,8 @@ struct sPAPRMachineState {
>  #define KVMPPC_H_LOGICAL_MEMOP  (KVMPPC_HCALL_BASE + 0x1)
>  /* Client Architecture support */
>  #define KVMPPC_H_CAS            (KVMPPC_HCALL_BASE + 0x2)
> -#define KVMPPC_HCALL_MAX        KVMPPC_H_CAS
> +#define KVMPPC_H_UPDATE_DT      (KVMPPC_HCALL_BASE + 0x3)
> +#define KVMPPC_HCALL_MAX        KVMPPC_H_UPDATE_DT
>  
>  typedef struct sPAPRDeviceTreeUpdateHeader {
>      uint32_t version_id;
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 17ea77618c..b471f7e1ff 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -1453,7 +1453,9 @@ static void ppc_spapr_reset(void)
>      /* Load the fdt */
>      qemu_fdt_dumpdtb(fdt, fdt_totalsize(fdt));
>      cpu_physical_memory_write(fdt_addr, fdt, fdt_totalsize(fdt));
> -    g_free(fdt);
> +    g_free(spapr->fdt_blob);
> +    spapr->fdt_blob = fdt;
> +    spapr->fdt_size = fdt_totalsize(fdt);

I did not commit this line removal to my local git so it fails to compile,
the rest should still compile. And it is an rfc anyway :)


-- 
Alexey