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Re: [Qemu-ppc] [PATCH qemu RFC 4/4] spapr: Implement SLOF-less client_ar
From: |
Alexey Kardashevskiy |
Subject: |
Re: [Qemu-ppc] [PATCH qemu RFC 4/4] spapr: Implement SLOF-less client_architecture_support |
Date: |
Mon, 29 Jul 2019 15:03:07 +1000 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 |
On 28/07/2019 16:09, David Gibson wrote:
> On Sat, Jul 20, 2019 at 11:28:50AM +1000, Alexey Kardashevskiy wrote:
>> QEMU already implements H_CAS called by SLOF. The existing handler
>> prepares a diff FDT and SLOF applies it on top of its current tree.
>> In SLOF-less setup when the user explicitly selected "bios=no",
>> this updates the FDT from the OS, updates it and writes back to the OS.
>> The new behavior is advertised to the OS via "/chosen/qemu,h_cas".
>
> I don't love having two different paths here, I'm wondering if we can
> unify things at all.
>
> I have wondered at some points if there's anything preventing us just
> giving a whole new device tree at CAS, rather than selected updates -
> that could simplify several things.
An update has a header, and this patch just copies the fdt over, if I
add a header to this new path, this will require a few more changes in
the guest which I would rather avoid. Thanks,
>
>> Signed-off-by: Alexey Kardashevskiy <address@hidden>
>> ---
>> include/hw/ppc/spapr.h | 5 +++++
>> hw/ppc/spapr.c | 24 ++++++++++++++++-----
>> hw/ppc/spapr_hcall.c | 49 +++++++++++++++++++++++++++++++++++++++---
>> 3 files changed, 70 insertions(+), 8 deletions(-)
>>
>> diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
>> index 7f5d7a70d27e..73cd9cf25b83 100644
>> --- a/include/hw/ppc/spapr.h
>> +++ b/include/hw/ppc/spapr.h
>> @@ -766,9 +766,14 @@ struct SpaprEventLogEntry {
>>
>> void spapr_events_init(SpaprMachineState *sm);
>> void spapr_dt_events(SpaprMachineState *sm, void *fdt);
>> +int spapr_h_cas_do_compose_response(SpaprMachineState *spapr, void *fdt,
>> + SpaprOptionVector *ov5_updates);
>> int spapr_h_cas_compose_response(SpaprMachineState *sm,
>> target_ulong addr, target_ulong size,
>> SpaprOptionVector *ov5_updates);
>> +#define FDT_MAX_SIZE 0x100000
>> +void *spapr_build_fdt(SpaprMachineState *spapr);
>> +
>> void close_htab_fd(SpaprMachineState *spapr);
>> void spapr_setup_hpt_and_vrma(SpaprMachineState *spapr);
>> void spapr_free_hpt(SpaprMachineState *spapr);
>> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
>> index b097a99951f1..f84895f4a8b4 100644
>> --- a/hw/ppc/spapr.c
>> +++ b/hw/ppc/spapr.c
>> @@ -978,6 +978,19 @@ static bool spapr_hotplugged_dev_before_cas(void)
>> return false;
>> }
>>
>> +int spapr_h_cas_do_compose_response(SpaprMachineState *spapr, void *fdt,
>> + SpaprOptionVector *ov5_updates)
>
> Not a great function name.
>
>> +{
>> + /* Fixup cpu nodes */
>> + _FDT((spapr_fixup_cpu_dt(fdt, spapr)));
>> +
>> + if (spapr_dt_cas_updates(spapr, fdt, ov5_updates)) {
>> + return -1;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> int spapr_h_cas_compose_response(SpaprMachineState *spapr,
>> target_ulong addr, target_ulong size,
>> SpaprOptionVector *ov5_updates)
>> @@ -1009,10 +1022,7 @@ int spapr_h_cas_compose_response(SpaprMachineState
>> *spapr,
>> _FDT((fdt_open_into(fdt_skel, fdt, size)));
>> g_free(fdt_skel);
>>
>> - /* Fixup cpu nodes */
>> - _FDT((spapr_fixup_cpu_dt(fdt, spapr)));
>> -
>> - if (spapr_dt_cas_updates(spapr, fdt, ov5_updates)) {
>> + if (spapr_h_cas_do_compose_response(spapr, fdt, ov5_updates)) {
>> return -1;
>> }
>>
>> @@ -1232,6 +1242,10 @@ static void spapr_dt_chosen(SpaprMachineState *spapr,
>> void *fdt)
>>
>> /* We always implemented RTAS as hcall, tell guests to call it directly
>> */
>> _FDT(fdt_setprop_cell(fdt, chosen, "qemu,h_rtas", 1));
>> + /* Tell the guest that H_CAS will return the entire FDT now, not the
>> diff */
>> + if (!spapr->bios_enabled) {
>> + _FDT(fdt_setprop_cell(fdt, chosen, "qemu,h_cas", 1));
>
> As with H_RTAS< using qemu,hypertas-functions would be more
> appropriate for this.
>
>> + }
>>
>> spapr_dt_ov5_platform_support(spapr, fdt, chosen);
>>
>> @@ -1262,7 +1276,7 @@ static void spapr_dt_hypervisor(SpaprMachineState
>> *spapr, void *fdt)
>> }
>> }
>>
>> -static void *spapr_build_fdt(SpaprMachineState *spapr)
>> +void *spapr_build_fdt(SpaprMachineState *spapr)
>> {
>> MachineState *machine = MACHINE(spapr);
>> MachineClass *mc = MACHINE_GET_CLASS(machine);
>> diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c
>> index b964d94f330b..c5cb06c9d507 100644
>> --- a/hw/ppc/spapr_hcall.c
>> +++ b/hw/ppc/spapr_hcall.c
>> @@ -17,6 +17,7 @@
>> #include "hw/ppc/spapr_ovec.h"
>> #include "mmu-book3s-v3.h"
>> #include "hw/mem/memory-device.h"
>> +#include "sysemu/device_tree.h"
>>
>> static bool has_spr(PowerPCCPU *cpu, int spr)
>> {
>> @@ -1774,9 +1775,51 @@ static target_ulong
>> h_client_architecture_support(PowerPCCPU *cpu,
>> /* legacy hash or new hash: */
>> spapr_setup_hpt_and_vrma(spapr);
>> }
>> - spapr->cas_reboot =
>> - (spapr_h_cas_compose_response(spapr, args[1], args[2],
>> - ov5_updates) != 0);
>> +
>> + if (spapr->bios_enabled) {
>> + spapr->cas_reboot =
>> + (spapr_h_cas_compose_response(spapr, args[1], args[2],
>> + ov5_updates) != 0);
>> + } else {
>> + int size;
>> + void *fdt, *fdt_skel;
>> + struct fdt_header hdr = { 0 };
>> +
>> + cpu_physical_memory_read(args[1], &hdr, sizeof(hdr));
>> + size = fdt32_to_cpu(hdr.totalsize);
>> + if (size > FDT_MAX_SIZE) {
>> + return H_NOT_AVAILABLE;
>> + }
>> +
>> + fdt_skel = g_malloc0(size);
>> + cpu_physical_memory_read(args[1], fdt_skel, size);
>> +
>> + fdt = g_malloc0(FDT_MAX_SIZE);
>> + fdt_open_into(fdt_skel, fdt, FDT_MAX_SIZE);
>> + g_free(fdt_skel);
>
> fdt_open_into() explicitly permits using the same buffer for both
> arguments, so you don't need two allocations here - you can just
> allocate FDT_MAX_SIZE, read it in, then fdt_open_into() in place.
>
> You probably should check for errors from fdt_open_into(), though.
>
>> +
>> + if (spapr_h_cas_do_compose_response(spapr, fdt, ov5_updates)) {
>> + g_free(fdt);
>> + return H_NOT_AVAILABLE;
>> + }
>> + fdt_pack(fdt);
>> + if (fdt_totalsize(fdt) > FDT_MAX_SIZE) {
>
> This can't actually happen - you only ever allocated a buffer of size
> FDT_MAX_SIZE, so if the DT was going to exceed that you would have hit
> FDT_ERR_NOSPACE in an earlier step.
>
>> + error_report("FDT too big ! 0x%x bytes (max is 0x%x)",
>> + fdt_totalsize(fdt), FDT_MAX_SIZE);
>> + g_free(fdt);
>> + return H_NOT_AVAILABLE;
>> + }
>> +
>> + /* Load the fdt */
>> + cpu_physical_memory_write(args[1], fdt, fdt_totalsize(fdt));
>> +
>> + g_free(spapr->fdt_blob);
>> + spapr->fdt_size = fdt_totalsize(fdt);
>> + spapr->fdt_initial_size = spapr->fdt_size;
>> + spapr->fdt_blob = fdt;
>> +
>> + qemu_fdt_dumpdtb(fdt, fdt_totalsize(fdt));
>> + }
>> }
>>
>> /*
>
--
Alexey
- Re: [Qemu-ppc] [PATCH qemu RFC 3/4] spapr: Advertise H_RTAS to the guest, (continued)
[Qemu-ppc] [PATCH qemu RFC 1/4] spapr: Allow changing kernel loading address, Alexey Kardashevskiy, 2019/07/19
[Qemu-ppc] [PATCH qemu RFC 2/4] spapr: Allow bios-less configuration, Alexey Kardashevskiy, 2019/07/19
[Qemu-ppc] [PATCH qemu RFC 4/4] spapr: Implement SLOF-less client_architecture_support, Alexey Kardashevskiy, 2019/07/19