On 7/11/19 9:57 AM, Michael Ellerman wrote: > Claudio Carvalho <cclaudio@xxxxxxxxxxxxx> writes: >> From: Ram Pai <linuxram@xxxxxxxxxx> >> >> Add the ucall() function, which can be used to make ultravisor calls >> with varied number of in and out arguments. Ultravisor calls can be made >> from the host or guests. >> >> This copies the implementation of plpar_hcall(). > .. with quite a few changes? > > This is one of the things I'd like to see in a Documentation file, so > that people can review the implementation vs the specification. I will document this (and other things) in a file under Documentation/powerpc. > >> Signed-off-by: Ram Pai <linuxram@xxxxxxxxxx> >> [ Change ucall.S to not save CR, rename and move headers, build ucall.S >> if CONFIG_PPC_POWERNV set, use R3 for the ucall number and add some >> comments in the code ] > Why are we not saving CR? See previous comment about Documentation :) > >> Signed-off-by: Claudio Carvalho <cclaudio@xxxxxxxxxxxxx> >> --- >> arch/powerpc/include/asm/ultravisor-api.h | 20 +++++++++++++++ >> arch/powerpc/include/asm/ultravisor.h | 20 +++++++++++++++ >> arch/powerpc/kernel/Makefile | 2 +- >> arch/powerpc/kernel/ucall.S | 30 +++++++++++++++++++++++ >> arch/powerpc/kernel/ultravisor.c | 4 +++ >> 5 files changed, 75 insertions(+), 1 deletion(-) >> create mode 100644 arch/powerpc/include/asm/ultravisor-api.h >> create mode 100644 arch/powerpc/kernel/ucall.S >> >> diff --git a/arch/powerpc/include/asm/ultravisor-api.h b/arch/powerpc/include/asm/ultravisor-api.h >> new file mode 100644 >> index 000000000000..49e766adabc7 >> --- /dev/null >> +++ b/arch/powerpc/include/asm/ultravisor-api.h >> @@ -0,0 +1,20 @@ >> +/* SPDX-License-Identifier: GPL-2.0 */ >> +/* >> + * Ultravisor API. >> + * >> + * Copyright 2019, IBM Corporation. >> + * >> + */ >> +#ifndef _ASM_POWERPC_ULTRAVISOR_API_H >> +#define _ASM_POWERPC_ULTRAVISOR_API_H >> + >> +#include <asm/hvcall.h> >> + >> +/* Return codes */ >> +#define U_NOT_AVAILABLE H_NOT_AVAILABLE >> +#define U_SUCCESS H_SUCCESS >> +#define U_FUNCTION H_FUNCTION >> +#define U_PARAMETER H_PARAMETER > Is there any benefit in redefining these? > >> diff --git a/arch/powerpc/include/asm/ultravisor.h b/arch/powerpc/include/asm/ultravisor.h >> index e5009b0d84ea..a78a2dacfd0b 100644 >> --- a/arch/powerpc/include/asm/ultravisor.h >> +++ b/arch/powerpc/include/asm/ultravisor.h >> @@ -8,8 +8,28 @@ >> #ifndef _ASM_POWERPC_ULTRAVISOR_H >> #define _ASM_POWERPC_ULTRAVISOR_H >> >> +#include <asm/ultravisor-api.h> >> + >> +#if !defined(__ASSEMBLY__) > Just #ifndef is fine. > >> /* Internal functions */ > How is it internal? > >> extern int early_init_dt_scan_ultravisor(unsigned long node, const char *uname, >> int depth, void *data); >> >> +/* API functions */ >> +#define UCALL_BUFSIZE 4 > Please don't copy this design from the hcall code, it has led to bugs in > the past. > > See my (still unmerged) attempt to fix this for the hcall case: > https://patchwork.ozlabs.org/patch/683577/ > > Basically instead of asking callers nicely to define a certain sized > buffer, and them forgetting, define a proper type that has the right size. I will keep that in mind. For now I think we don't need that since the v5 will have ucall_norets() instead. > >> +/** >> + * ucall: Make a powerpc ultravisor call. >> + * @opcode: The ultravisor call to make. >> + * @retbuf: Buffer to store up to 4 return arguments in. >> + * >> + * This call supports up to 6 arguments and 4 return arguments. Use >> + * UCALL_BUFSIZE to size the return argument buffer. >> + */ >> +#if defined(CONFIG_PPC_POWERNV) > #ifdef > >> +long ucall(unsigned long opcode, unsigned long *retbuf, ...); >> +#endif >> + >> +#endif /* !__ASSEMBLY__ */ >> + >> #endif /* _ASM_POWERPC_ULTRAVISOR_H */ >> diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile >> index f0caa302c8c0..f28baccc0a79 100644 >> --- a/arch/powerpc/kernel/Makefile >> +++ b/arch/powerpc/kernel/Makefile >> @@ -154,7 +154,7 @@ endif >> >> obj-$(CONFIG_EPAPR_PARAVIRT) += epapr_paravirt.o epapr_hcalls.o >> obj-$(CONFIG_KVM_GUEST) += kvm.o kvm_emul.o >> -obj-$(CONFIG_PPC_POWERNV) += ultravisor.o >> +obj-$(CONFIG_PPC_POWERNV) += ultravisor.o ucall.o > Same comment about being platforms/powernv ? >> diff --git a/arch/powerpc/kernel/ucall.S b/arch/powerpc/kernel/ucall.S >> new file mode 100644 >> index 000000000000..1678f6eb7230 >> --- /dev/null >> +++ b/arch/powerpc/kernel/ucall.S >> @@ -0,0 +1,30 @@ >> +/* SPDX-License-Identifier: GPL-2.0 */ >> +/* >> + * Generic code to perform an ultravisor call. >> + * >> + * Copyright 2019, IBM Corporation. >> + * >> + */ >> +#include <asm/ppc_asm.h> >> + >> +/* >> + * This function is based on the plpar_hcall() > I don't think it meaningfully is any more. > >> + */ >> +_GLOBAL_TOC(ucall) > You don't need the TOC setup here (unless a later patch does?). > >> + std r4,STK_PARAM(R4)(r1) /* Save ret buffer */ >> + mr r4,r5 >> + mr r5,r6 >> + mr r6,r7 >> + mr r7,r8 >> + mr r8,r9 >> + mr r9,r10 > Below you space the arguments, here you don't. Pick one or the other please. > >> + >> + sc 2 /* Invoke the ultravisor */ >> + >> + ld r12,STK_PARAM(R4)(r1) >> + std r4, 0(r12) >> + std r5, 8(r12) >> + std r6, 16(r12) >> + std r7, 24(r12) >> + >> + blr /* Return r3 = status */ >> diff --git a/arch/powerpc/kernel/ultravisor.c b/arch/powerpc/kernel/ultravisor.c >> index dc6021f63c97..02ddf79a9522 100644 >> --- a/arch/powerpc/kernel/ultravisor.c >> +++ b/arch/powerpc/kernel/ultravisor.c >> @@ -8,10 +8,14 @@ >> #include <linux/init.h> >> #include <linux/printk.h> >> #include <linux/string.h> >> +#include <linux/export.h> >> >> #include <asm/ultravisor.h> >> #include <asm/firmware.h> >> >> +/* in ucall.S */ >> +EXPORT_SYMBOL_GPL(ucall); > This should be in ucall.S Here I'm following the same way that hypercall wrapper symbols are exported. Last time I tried to export that in ucall.S the linker complained that the ucall symbol will not be versioned. Something like this: https://patchwork.kernel.org/patch/9452759/ Thanks, Claudio > > cheers
