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| From: | BALATON Zoltan |
| Subject: | Re: [PATCH qemu v20] spapr: Implement Open Firmware client interface |
| Date: | Sun, 23 May 2021 14:12:08 +0200 (CEST) |
On Sun, 23 May 2021, Alexey Kardashevskiy wrote:
On 22/05/2021 23:08, BALATON Zoltan wrote:On Sat, 22 May 2021, Alexey Kardashevskiy wrote:On 22/05/2021 05:57, BALATON Zoltan wrote:On Fri, 21 May 2021, BALATON Zoltan wrote:On Fri, 21 May 2021, Alexey Kardashevskiy wrote:On 21/05/2021 07:59, BALATON Zoltan wrote:On Thu, 20 May 2021, Alexey Kardashevskiy wrote:The PAPR platform describes an OS environment that's presented by a combination of a hypervisor and firmware. The features it specifies require collaboration between the firmware and the hypervisor. Since the beginning, the runtime component of the firmware (RTAS) has been implemented as a 20 byte shim which simply forwards it to a hypercall implemented in qemu. The boot time firmware component isSLOF - but a build that's specific to qemu, and has always needed to be updated in sync with it. Even though we've managed to limit the amountof runtime communication we need between qemu and SLOF, there's some, and it has become increasingly awkward to handle as we've implemented new features. This implements a boot time OF client interface (CI) which isenabled by a new "x-vof" pseries machine option (stands for "Virtual OpenFirmware). When enabled, QEMU implements the custom H_OF_CLIENT hcall which implements Open Firmware Client Interface (OF CI). This allows using a smaller stateless firmware which does not have to manage the device tree. The new "vof.bin" firmware image is included with source code under pc-bios/. It also includes RTAS blob. This implements a handful of CI methods just to get -kernel/-initrd working. In particular, this implements the device tree fetching andsimple memory allocator - "claim" (an OF CI memory allocator) and updates"/memory@0/available" to report the client about available memory.This implements changing some device tree properties which we know howto deal with, the rest is ignored. To allow changes, this skips fdt_pack() when x-vof=on as not packing the blob leaves some room for appending.In absence of SLOF, this assigns phandles to device tree nodes to makedevice tree traversing work. When x-vof=on, this adds "/chosen" every time QEMU (re)builds a tree. This adds basic instances support which are managed by a hash map ihandle -> [phandle]. Before the guest started, the used memory is: 0..e60 - the initial firmware 8000..10000 - stack 400000.. - kernel 3ea0000.. - initramdisk This OF CI does not implement "interpret". Unlike SLOF, this does not format uninitialized nvram. Instead, this includes a disk image with pre-formatted nvram. With this basic support, this can only boot into kernel directly.However this is just enough for the petitboot kernel and initradmdisk to boot from any possible source. Note this requires reasonably recent guestkernel with:https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=df5be5be8735 The immediate benefit is much faster booting time which especially crucial with fully emulated early CPU bring up environments. Also thismay come handy when/if GRUB-in-the-userspace sees light of the day. This separates VOF and sPAPR in a hope that VOF bits may be reused by other POWERPC boards which do not support pSeries.This is coded in assumption that later on we might be adding support forbooting from QEMU backends (blockdev is the first candidate) without devices/drivers in between as OF1275 does not require that and it is quite easy to so. Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> --- The example command line is: /home/aik/pbuild/qemu-killslof-localhost-ppc64/qemu-system-ppc64 \ -nodefaults \ -chardev stdio,id=STDIO0,signal=off,mux=on \ -device spapr-vty,id=svty0,reg=0x71000110,chardev=STDIO0 \ -mon id=MON0,chardev=STDIO0,mode=readline \ -nographic \ -vga none \ -enable-kvm \ -m 8G \-machine pseries,x-vof=on,cap-cfpc=broken,cap-sbbc=broken,cap-ibs=broken,cap-ccf-assist=off \-kernel pbuild/kernel-le-guest/vmlinux \ -initrd pb/rootfs.cpio.xz \-drive id=DRIVE0,if=none,file=./p/qemu-killslof/pc-bios/vof-nvram.bin,format=raw \-global spapr-nvram.drive=DRIVE0 \ -snapshot \ -smp 8,threads=8 \ -L /home/aik/t/qemu-ppc64-bios/ \ -trace events=qemu_trace_events \ -d guest_errors \ -chardev socket,id=SOCKET0,server,nowait,path=qemu.mon.tmux26 \ -mon chardev=SOCKET0,mode=control --- Changes: v20: * compile vof.bin with -mcpu=power4 for better compatibility * s/std/stw/ in entry.S to make it work on ppc32 * fixed dt_available property to support both 32 and 64bit * shuffled prom_args handling code * do not enforce 32bit in MSR (again, to support 32bit platforms)[...]diff --git a/default-configs/devices/ppc64-softmmu.mak b/default-configs/devices/ppc64-softmmu.makindex ae0841fa3a18..9fb201dfacfa 100644 --- a/default-configs/devices/ppc64-softmmu.mak +++ b/default-configs/devices/ppc64-softmmu.mak @@ -9,3 +9,4 @@ CONFIG_POWERNV=y # For pSeries CONFIG_PSERIES=y CONFIG_NVDIMM=y +CONFIG_VOF=y diff --git a/hw/ppc/Kconfig b/hw/ppc/Kconfig index e51e0e5e5ac6..964510dfc73d 100644 --- a/hw/ppc/Kconfig +++ b/hw/ppc/Kconfig @@ -143,3 +143,6 @@ config FW_CFG_PPC config FDT_PPC bool + +config VOF + boolI think you should just add "select VOF" to config PSERIES section in Kconfig instead of adding it to default-configs/devices/ppc64-softmmu.mak.oh well, can do that too.I think most config options should be selected by KConfig and the default config should only include machines, otherwise VOF would be added also when you don't compile PSERIES or PEGASOS2. With select in Kconfig it will be added when needed. That's why it's better to use select in this case.That should do it, it works in my updated pegasos2 patch:https://osdn.net/projects/qmiga/scm/git/qemu/commits/3c1fad08469b4d3c04def22044e52b2d27774a61 [...]diff --git a/pc-bios/vof/entry.S b/pc-bios/vof/entry.S new file mode 100644 index 000000000000..569688714c91 --- /dev/null +++ b/pc-bios/vof/entry.S @@ -0,0 +1,51 @@ +#define LOAD32(rn, name) \ + lis rn,name##@h; \ + ori rn,rn,name##@l + +#define ENTRY(func_name) \ + .text; \ + .align 2; \ + .globl .func_name; \ + .func_name: \ + .globl func_name; \ + func_name: + +#define KVMPPC_HCALL_BASE 0xf000 +#define KVMPPC_H_RTAS (KVMPPC_HCALL_BASE + 0x0) +#define KVMPPC_H_VOF_CLIENT (KVMPPC_HCALL_BASE + 0x5) + + . = 0x100 /* Do exactly as SLOF does */ + +ENTRY(_start) +# LOAD32(%r31, 0) /* Go 32bit mode */ +# mtmsrd %r31,0 + LOAD32(2, __toc_start) + b entry_c + +ENTRY(_prom_entry) + LOAD32(2, __toc_start) + stwu %r1,-112(%r1) + stw %r31,104(%r1) + mflr %r31 + bl prom_entry + nop + mtlr %r31 + ld %r31,104(%r1)It's getting there, now I see the first client call from the guest boot code but then it crashes on this ld opcode which apparently is 64 bit only:Oh right.Hopefully this is the last such opcode left before I can really test this.Make it lwz, and test it?Yes, figured that out too after sending this message. Replacing with lwz works but I wonder that now you have stwu lwz do the stack offsets need adjusting too or you just waste 4 bytes now? With lwz here I found no further 64 bit opcodes and the guest boot code could walk the device tree. It failed later but I think that's because I'll need to fill more info about the machine in the device tree. I'll experiment with that but it looks like it could work at least for MorphOS. I'll have to try Linux too.I was trying to get a linux kernel from a debian powerpc iso to do something (debian before 10.0 has Pegasos support) but I've run into the problem that the kernel is loaded at 0x400000 but the start address is at some offset from that. How do I set qemu,boot-kernel in this case?The pseries kernel can work from any location (and it relocates itself to 0 at some point) even though it is linked at c000.0000.0000.0000, and there is no start address offset:===objdump -D ~/pbuild/kernel-le/vmlinux/home/aik/pbuild/kernel-le/vmlinux: file format elf64-powerpcle Disassembly of section .head.text: c000000000000000 <__start>: c000000000000000: 48 00 00 08 tdi 0,r0,72c000000000000004: 2c 00 00 48 b c000000000000030 <__start+0x30>... === Not sure about pegasos2 kernels (or any ppc32 really), sorry.The kernel from Debian 10.0 powerpc used on pegasos looks like this: vmlinuz-chrp.initrd: file format elf32-powerpc vmlinuz-chrp.initrd architecture: powerpc:common, flags 0x00000112: EXEC_P, HAS_SYMS, D_PAGED start address 0x004002fc Program Header: LOAD off 0x00010000 vaddr 0x00400000 paddr 0x00400000 align 2**16 filesz 0x0127b72a memsz 0x0127d5d8 flags rwx STACK off 0x00000000 vaddr 0x00000000 paddr 0x00000000 align 2**4 filesz 0x00000000 memsz 0x00000000 flags rwx NOTE off 0x000000b4 vaddr 0x00000000 paddr 0x00000000 align 2**0 filesz 0x0000002c memsz 0x00000000 flags --- NOTE off 0x000000e0 vaddr 0x00000000 paddr 0x00000000 align 2**0 filesz 0x0000002c memsz 0x00000000 flags --- Sections: Idx Name Size VMA LMA File off Algn 0 .text 00008588 00400000 00400000 00010000 2**2 CONTENTS, ALLOC, LOAD, READONLY, CODE 1 .text.unlikely 00000078 00408588 00408588 00018588 2**2 CONTENTS, ALLOC, LOAD, READONLY, CODE 2 .data 00001bec 00409000 00409000 00019000 2**2 CONTENTS, ALLOC, LOAD, DATA 3 .got 0000000c 0040abec 0040abec 0001abec 2**2 CONTENTS, ALLOC, LOAD, DATA 4 __builtin_cmdline 00000800 0040abf8 0040abf8 0001abf8 2**2 CONTENTS, ALLOC, LOAD, DATA 5 .kernel:vmlinux.strip 0047658e 0040c000 0040c000 0001c000 2**0 CONTENTS, ALLOC, LOAD, READONLY, DATA 6 .kernel:initrd 00df872a 00883000 00883000 00493000 2**0 CONTENTS, ALLOC, LOAD, READONLY, DATA 7 .bss 000015d8 0167c000 0167c000 0128b72a 2**2 ALLOC 8 .debug_info 0000e7fd 00000000 00000000 0128b72a 2**0 CONTENTS, READONLY, DEBUGGING 9 .debug_abbrev 00002a4f 00000000 00000000 01299f27 2**0 CONTENTS, READONLY, DEBUGGING 10 .debug_loc 00009df1 00000000 00000000 0129c976 2**0 CONTENTS, READONLY, DEBUGGING 11 .debug_aranges 00000250 00000000 00000000 012a6767 2**0 CONTENTS, READONLY, DEBUGGING 12 .debug_line 000026b8 00000000 00000000 012a69b7 2**0 CONTENTS, READONLY, DEBUGGING 13 .debug_str 00001d9c 00000000 00000000 012a906f 2**0 CONTENTS, READONLY, DEBUGGING 14 .comment 0000001d 00000000 00000000 012aae0b 2**0 CONTENTS, READONLY 15 .gnu.attributes 00000010 00000000 00000000 012aae28 2**0 CONTENTS, READONLY 16 .debug_frame 00001c88 00000000 00000000 012aae38 2**2 CONTENTS, READONLY, DEBUGGING 17 .debug_ranges 00000740 00000000 00000000 012acac0 2**0 CONTENTS, READONLY, DEBUGGINGIt even seems to have the initrd embedded in it. If I just use 0x400000 as start address it does not work, has to jump to the start address for it to start correctly.Because when I set it to the address/size where the kernel is loaded it jumps to the beginnig not the correct start address. If I set the address to the start address then size will be wrong so I don't know how to set qemu,boot-kernel in this case or is there another property to tell the start address? (Vof does not seem to check any other property and seems to assume the entry point is the same as the load address but for this linux kernel it's not.)I guess if you really need an offset, you'll have to add a new property ("qemu,boot-kernel-start"?) and look for it in the firmware. Or, say, put in gpr5 in your version of spapr_cpu_set_entry_state() and make boot_from_memory() use it.Either way would work but I don't want to recompile vof.bin so if youI really do not want to add features with no user for it; and having this added with pegasos2 support make it clear why it is there. Also recompile is really simple :)
Provided you have a cross compiler set up and do not run into problems you've mentioned before. So I'd prefer to not increase the source of bugs by also modifying VOF. This is not only for pegasos2. An ELF file does not necessarily have the entry point equal to its load address so while you happen to have a kernel that does that now you could have another later that won't so supporting it in some way would be the right thing to do anyway. Also I can't decide what is better, using a gpr or a device tree property so whatever you prefer. You probably need a respin anyway so adding it to that seems to be simpler than for me to try starting compiling and testing VOF too (also I can't test with spapr so can't make sure the changes I make won't break something). So you seem to be a better position for VOF changes. I think I only need these:
1. Get rid of the ld 64 bit opcode in _prom_entry 2. Support ELF with entry point != load address3. Have a way to disable ci_entry after quiesce so it won't do sc 1 that would generate exception in my case otherwise or ignore that exception within VOF.
I think other issues have been already resolved with your latest patch version unless I forgot something.
Regards, BALATON Zoltan
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