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    SubjectRe: [PATCH v2 2/3] RISC-V: Add basic support for SBI v0.2
    On Fri, Sep 27, 2019 at 5:39 AM Atish Patra <atish.patra@wdc.com> wrote:
    >
    > The SBI v0.2 introduces a base extension which is backward compatible
    > with v0.1. Implement all helper functions and minimum required SBI
    > calls from v0.2 for now. All other base extension function will be
    > added later as per need.
    > As v0.2 calling convention is backward compatible with v0.1, remove
    > the v0.1 helper functions and just use v0.2 calling convention.
    >
    > Signed-off-by: Atish Patra <atish.patra@wdc.com>
    > ---
    > arch/riscv/include/asm/sbi.h | 139 ++++++++++----------
    > arch/riscv/kernel/Makefile | 1 +
    > arch/riscv/kernel/sbi.c | 241 +++++++++++++++++++++++++++++++++++
    > arch/riscv/kernel/setup.c | 2 +
    > 4 files changed, 311 insertions(+), 72 deletions(-)
    > create mode 100644 arch/riscv/kernel/sbi.c
    >
    > diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h
    > index 2147f384fad0..279b7f10b3c2 100644
    > --- a/arch/riscv/include/asm/sbi.h
    > +++ b/arch/riscv/include/asm/sbi.h
    > @@ -8,93 +8,88 @@
    >
    > #include <linux/types.h>
    >
    > -#define SBI_EXT_0_1_SET_TIMER 0x0
    > -#define SBI_EXT_0_1_CONSOLE_PUTCHAR 0x1
    > -#define SBI_EXT_0_1_CONSOLE_GETCHAR 0x2
    > -#define SBI_EXT_0_1_CLEAR_IPI 0x3
    > -#define SBI_EXT_0_1_SEND_IPI 0x4
    > -#define SBI_EXT_0_1_REMOTE_FENCE_I 0x5
    > -#define SBI_EXT_0_1_REMOTE_SFENCE_VMA 0x6
    > -#define SBI_EXT_0_1_REMOTE_SFENCE_VMA_ASID 0x7
    > -#define SBI_EXT_0_1_SHUTDOWN 0x8
    > +enum sbi_ext_id {
    > + SBI_EXT_0_1_SET_TIMER = 0x0,
    > + SBI_EXT_0_1_CONSOLE_PUTCHAR = 0x1,
    > + SBI_EXT_0_1_CONSOLE_GETCHAR = 0x2,
    > + SBI_EXT_0_1_CLEAR_IPI = 0x3,
    > + SBI_EXT_0_1_SEND_IPI = 0x4,
    > + SBI_EXT_0_1_REMOTE_FENCE_I = 0x5,
    > + SBI_EXT_0_1_REMOTE_SFENCE_VMA = 0x6,
    > + SBI_EXT_0_1_REMOTE_SFENCE_VMA_ASID = 0x7,
    > + SBI_EXT_0_1_SHUTDOWN = 0x8,
    > + SBI_EXT_BASE = 0x10,
    > +};
    >
    > -#define SBI_CALL(which, arg0, arg1, arg2, arg3) ({ \
    > - register uintptr_t a0 asm ("a0") = (uintptr_t)(arg0); \
    > - register uintptr_t a1 asm ("a1") = (uintptr_t)(arg1); \
    > - register uintptr_t a2 asm ("a2") = (uintptr_t)(arg2); \
    > - register uintptr_t a3 asm ("a3") = (uintptr_t)(arg3); \
    > - register uintptr_t a7 asm ("a7") = (uintptr_t)(which); \
    > - asm volatile ("ecall" \
    > - : "+r" (a0) \
    > - : "r" (a1), "r" (a2), "r" (a3), "r" (a7) \
    > - : "memory"); \
    > - a0; \
    > -})
    > +enum sbi_ext_base_fid {
    > + SBI_BASE_GET_SPEC_VERSION = 0,
    > + SBI_BASE_GET_IMP_ID,
    > + SBI_BASE_GET_IMP_VERSION,
    > + SBI_BASE_PROBE_EXT,
    > + SBI_BASE_GET_MVENDORID,
    > + SBI_BASE_GET_MARCHID,
    > + SBI_BASE_GET_MIMPID,
    > +};
    >
    > -/* Lazy implementations until SBI is finalized */
    > -#define SBI_CALL_0(which) SBI_CALL(which, 0, 0, 0, 0)
    > -#define SBI_CALL_1(which, arg0) SBI_CALL(which, arg0, 0, 0, 0)
    > -#define SBI_CALL_2(which, arg0, arg1) SBI_CALL(which, arg0, arg1, 0, 0)
    > -#define SBI_CALL_3(which, arg0, arg1, arg2) \
    > - SBI_CALL(which, arg0, arg1, arg2, 0)
    > -#define SBI_CALL_4(which, arg0, arg1, arg2, arg3) \
    > - SBI_CALL(which, arg0, arg1, arg2, arg3)
    > +#define SBI_SPEC_VERSION_DEFAULT 0x1
    > +#define SBI_SPEC_VERSION_MAJOR_OFFSET 24
    > +#define SBI_SPEC_VERSION_MAJOR_MASK 0x7f
    > +#define SBI_SPEC_VERSION_MINOR_MASK 0xffffff
    >
    > -static inline void sbi_console_putchar(int ch)
    > -{
    > - SBI_CALL_1(SBI_EXT_0_1_CONSOLE_PUTCHAR, ch);
    > -}
    > +/* SBI return error codes */
    > +#define SBI_SUCCESS 0
    > +#define SBI_ERR_FAILURE -1
    > +#define SBI_ERR_NOT_SUPPORTED -2
    > +#define SBI_ERR_INVALID_PARAM -3
    > +#define SBI_ERR_DENIED -4
    > +#define SBI_ERR_INVALID_ADDRESS -5
    >
    > -static inline int sbi_console_getchar(void)
    > -{
    > - return SBI_CALL_0(SBI_EXT_0_1_CONSOLE_GETCHAR);
    > -}
    > -
    > -static inline void sbi_set_timer(uint64_t stime_value)
    > -{
    > -#if __riscv_xlen == 32
    > - SBI_CALL_2(SBI_EXT_0_1_SET_TIMER, stime_value,
    > - stime_value >> 32);
    > -#else
    > - SBI_CALL_1(SBI_EXT_0_1_SET_TIMER, stime_value);
    > -#endif
    > -}
    > +extern unsigned long sbi_spec_version;
    > +struct sbiret {
    > + long error;
    > + long value;
    > +};
    >
    > -static inline void sbi_shutdown(void)
    > -{
    > - SBI_CALL_0(SBI_EXT_0_1_SHUTDOWN);
    > -}
    > +void sbi_init(void);
    > +struct sbiret sbi_ecall(int ext, int fid, unsigned long arg0,
    > + unsigned long arg1, unsigned long arg2,
    > + unsigned long arg3);
    > +int sbi_err_map_linux_errorno(int err);
    >
    > -static inline void sbi_clear_ipi(void)
    > -{
    > - SBI_CALL_0(SBI_EXT_0_1_CLEAR_IPI);
    > -}
    > +void sbi_console_putchar(int ch);
    > +int sbi_console_getchar(void);
    > +void sbi_set_timer(uint64_t stime_value);
    > +void sbi_shutdown(void);
    > +void sbi_clear_ipi(void);
    > +void sbi_send_ipi(const unsigned long *hart_mask);
    > +void sbi_remote_fence_i(const unsigned long *hart_mask);
    > +void sbi_remote_sfence_vma(const unsigned long *hart_mask,
    > + unsigned long start,
    > + unsigned long size);
    >
    > -static inline void sbi_send_ipi(const unsigned long *hart_mask)
    > -{
    > - SBI_CALL_1(SBI_EXT_0_1_SEND_IPI, hart_mask);
    > -}
    > +void sbi_remote_sfence_vma_asid(const unsigned long *hart_mask,
    > + unsigned long start,
    > + unsigned long size,
    > + unsigned long asid);
    > +int sbi_probe_extension(long ext);
    >
    > -static inline void sbi_remote_fence_i(const unsigned long *hart_mask)
    > +/* Check if current SBI specification version is 0.1 or not */
    > +static inline int sbi_spec_is_0_1(void)
    > {
    > - SBI_CALL_1(SBI_EXT_0_1_REMOTE_FENCE_I, hart_mask);
    > + return (sbi_spec_version == SBI_SPEC_VERSION_DEFAULT) ? 1 : 0;
    > }
    >
    > -static inline void sbi_remote_sfence_vma(const unsigned long *hart_mask,
    > - unsigned long start,
    > - unsigned long size)
    > +/* Get the major version of SBI */
    > +static inline unsigned long sbi_major_version(void)
    > {
    > - SBI_CALL_3(SBI_EXT_0_1_REMOTE_SFENCE_VMA, hart_mask,
    > - start, size);
    > + return (sbi_spec_version >> SBI_SPEC_VERSION_MAJOR_OFFSET) &
    > + SBI_SPEC_VERSION_MAJOR_MASK;
    > }
    >
    > -static inline void sbi_remote_sfence_vma_asid(const unsigned long *hart_mask,
    > - unsigned long start,
    > - unsigned long size,
    > - unsigned long asid)
    > +/* Get the minor version of SBI */
    > +static inline unsigned long sbi_minor_version(void)
    > {
    > - SBI_CALL_4(SBI_EXT_0_1_REMOTE_SFENCE_VMA_ASID, hart_mask,
    > - start, size, asid);
    > + return sbi_spec_version & SBI_SPEC_VERSION_MINOR_MASK;
    > }
    >
    > #endif
    > diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
    > index 2420d37d96de..faf862d26924 100644
    > --- a/arch/riscv/kernel/Makefile
    > +++ b/arch/riscv/kernel/Makefile
    > @@ -17,6 +17,7 @@ obj-y += irq.o
    > obj-y += process.o
    > obj-y += ptrace.o
    > obj-y += reset.o
    > +obj-y += sbi.o
    > obj-y += setup.o
    > obj-y += signal.o
    > obj-y += syscall_table.o
    > diff --git a/arch/riscv/kernel/sbi.c b/arch/riscv/kernel/sbi.c
    > new file mode 100644
    > index 000000000000..315fcb925278
    > --- /dev/null
    > +++ b/arch/riscv/kernel/sbi.c
    > @@ -0,0 +1,241 @@
    > +// SPDX-License-Identifier: GPL-2.0-only
    > +/*
    > + * Copyright (c) 2019 Western Digital Corporation or its affiliates.
    > + */
    > +
    > +#include <asm/sbi.h>
    > +#include <linux/sched.h>
    > +
    > +/* default SBI version is 0.1 */
    > +unsigned long sbi_spec_version = SBI_SPEC_VERSION_DEFAULT;
    > +
    > +struct sbiret sbi_ecall(int ext, int fid, unsigned long arg0,
    > + unsigned long arg1, unsigned long arg2,
    > + unsigned long arg3)
    > +{
    > + struct sbiret ret;
    > +
    > + register uintptr_t a0 asm ("a0") = (uintptr_t)(arg0);
    > + register uintptr_t a1 asm ("a1") = (uintptr_t)(arg1);
    > + register uintptr_t a2 asm ("a2") = (uintptr_t)(arg2);
    > + register uintptr_t a3 asm ("a3") = (uintptr_t)(arg3);
    > + register uintptr_t a6 asm ("a6") = (uintptr_t)(fid);
    > + register uintptr_t a7 asm ("a7") = (uintptr_t)(ext);
    > + asm volatile ("ecall"
    > + : "+r" (a0), "+r" (a1)
    > + : "r" (a2), "r" (a3), "r" (a6), "r" (a7)
    > + : "memory");
    > + ret.error = a0;
    > + ret.value = a1;
    > +
    > + return ret;
    > +}
    > +
    > +int sbi_err_map_linux_errno(int err)
    > +{
    > + switch (err) {
    > + case SBI_SUCCESS:
    > + return 0;
    > + case SBI_ERR_DENIED:
    > + return -EPERM;
    > + case SBI_ERR_INVALID_PARAM:
    > + return -EINVAL;
    > + case SBI_ERR_INVALID_ADDRESS:
    > + return -EFAULT;
    > + case SBI_ERR_NOT_SUPPORTED:
    > + case SBI_ERR_FAILURE:
    > + default:
    > + return -ENOTSUPP;
    > + };
    > +}
    > +
    > +/**
    > + * sbi_console_putchar() - Writes given character to the console device.
    > + * @ch: The data to be written to the console.
    > + *
    > + * Return: None
    > + */
    > +void sbi_console_putchar(int ch)
    > +{
    > + sbi_ecall(SBI_EXT_0_1_CONSOLE_PUTCHAR, 0, ch, 0, 0, 0);
    > +}
    > +
    > +/**
    > + * sbi_console_getchar() - Reads a byte from console device.
    > + *
    > + * Returns the value read from console.
    > + */
    > +int sbi_console_getchar(void)
    > +{
    > + struct sbiret ret;
    > +
    > + ret = sbi_ecall(SBI_EXT_0_1_CONSOLE_GETCHAR, 0, 0, 0, 0, 0);
    > +
    > + return ret.error;
    > +}
    > +
    > +/**
    > + * sbi_set_timer() - Program the timer for next timer event.
    > + * @stime_value: The value after which next timer event should fire.
    > + *
    > + * Return: None
    > + */
    > +void sbi_set_timer(uint64_t stime_value)
    > +{
    > +#if __riscv_xlen == 32
    > + sbi_ecall(SBI_EXT_0_1_SET_TIMER, 0, stime_value,
    > + stime_value >> 32, 0, 0);
    > +#else
    > + sbi_ecall(SBI_EXT_0_1_SET_TIMER, 0, stime_value, 0, 0, 0);
    > +#endif
    > +}
    > +
    > +/**
    > + * sbi_shutdown() - Remove all the harts from executing supervisor code.
    > + *
    > + * Return: None
    > + */
    > +void sbi_shutdown(void)
    > +{
    > + sbi_ecall(SBI_EXT_0_1_SHUTDOWN, 0, 0, 0, 0, 0);
    > +}
    > +
    > +/**
    > + * sbi_clear_ipi() - Clear any pending IPIs for the calling hart.
    > + *
    > + * Return: None
    > + */
    > +void sbi_clear_ipi(void)
    > +{
    > + sbi_ecall(SBI_EXT_0_1_CLEAR_IPI, 0, 0, 0, 0, 0);
    > +}
    > +
    > +/**
    > + * sbi_send_ipi() - Send an IPI to any hart.
    > + * @hart_mask: A cpu mask containing all the target harts.
    > + *
    > + * Return: None
    > + */
    > +void sbi_send_ipi(const unsigned long *hart_mask)
    > +{
    > + sbi_ecall(SBI_EXT_0_1_SEND_IPI, 0, (unsigned long)hart_mask,
    > + 0, 0, 0);
    > +}
    > +
    > +/**
    > + * sbi_remote_fence_i() - Execute FENCE.I instruction on given remote harts.
    > + * @hart_mask: A cpu mask containing all the target harts.
    > + *
    > + * Return: None
    > + */
    > +void sbi_remote_fence_i(const unsigned long *hart_mask)
    > +{
    > + sbi_ecall(SBI_EXT_0_1_REMOTE_FENCE_I, 0, (unsigned long)hart_mask,
    > + 0, 0, 0);
    > +}
    > +
    > +/**
    > + * sbi_remote_sfence_vma() - Execute SFENCE.VMA instructions on given remote
    > + * harts for the specified virtual address range.
    > + * @hart_mask: A cpu mask containing all the target harts.
    > + * @start: Start of the virtual address
    > + * @size: Total size of the virtual address range.
    > + *
    > + * Return: None
    > + */
    > +void sbi_remote_sfence_vma(const unsigned long *hart_mask,
    > + unsigned long start,
    > + unsigned long size)
    > +{
    > + sbi_ecall(SBI_EXT_0_1_REMOTE_SFENCE_VMA, 0,
    > + (unsigned long)hart_mask, start, size, 0);
    > +}
    > +
    > +/**
    > + * sbi_remote_sfence_vma_asid() - Execute SFENCE.VMA instructions on given
    > + * remote harts for a virtual address range belonging to a specific ASID.
    > + *
    > + * @hart_mask: A cpu mask containing all the target harts.
    > + * @start: Start of the virtual address
    > + * @size: Total size of the virtual address range.
    > + * @asid: The value of address space identifier (ASID).
    > + *
    > + * Return: None
    > + */
    > +void sbi_remote_sfence_vma_asid(const unsigned long *hart_mask,
    > + unsigned long start,
    > + unsigned long size,
    > + unsigned long asid)
    > +{
    > + sbi_ecall(SBI_EXT_0_1_REMOTE_SFENCE_VMA_ASID, 0,
    > + (unsigned long)hart_mask, start, size, asid);
    > +}
    > +
    > +/**
    > + * sbi_probe_extension() - Check if an SBI extension ID is supported or not.
    > + * @extid: The extension ID to be probed.
    > + *
    > + * Return: Extension specific nonzero value if yes, -ENOTSUPP otherwise.
    > + */
    > +int sbi_probe_extension(long extid)
    > +{
    > + struct sbiret ret;
    > +
    > + ret = sbi_ecall(SBI_EXT_BASE, SBI_BASE_PROBE_EXT, 0, 0, 0, 0);
    > + if (!ret.error)
    > + if (ret.value)
    > + return ret.value;
    > +
    > + return -ENOTSUPP;
    > +}

    Please EXPORT() all public APIs of SBI.

    The KVM RISC-V does not compile as module if these public APIs are not
    exported.

    Regards,
    Anup

    > +
    > +static long sbi_get_spec_version(void)
    > +{
    > + struct sbiret ret;
    > +
    > + ret = sbi_ecall(SBI_EXT_BASE, SBI_BASE_GET_SPEC_VERSION,
    > + 0, 0, 0, 0);
    > + if (!ret.error)
    > + return ret.value;
    > + else
    > + return ret.error;
    > +}
    > +
    > +static long sbi_get_firmware_id(void)
    > +{
    > + struct sbiret ret;
    > +
    > + ret = sbi_ecall(SBI_EXT_BASE, SBI_BASE_GET_IMP_ID,
    > + 0, 0, 0, 0);
    > + if (!ret.error)
    > + return ret.value;
    > + else
    > + return sbi_err_map_linux_errno(ret.error);
    > +}
    > +
    > +static long sbi_get_firmware_version(void)
    > +{
    > + struct sbiret ret;
    > +
    > + ret = sbi_ecall(SBI_EXT_BASE, SBI_BASE_GET_IMP_VERSION,
    > + 0, 0, 0, 0);
    > + if (!ret.error)
    > + return ret.value;
    > + else
    > + return sbi_err_map_linux_errno(ret.error);
    > +}
    > +
    > +void sbi_init(void)
    > +{
    > + int ret;
    > +
    > + ret = sbi_get_spec_version();
    > + if (ret > 0)
    > + sbi_spec_version = ret;
    > +
    > + pr_info("SBI specification v%lu.%lu detected\n",
    > + sbi_major_version(), sbi_minor_version());
    > + if (!sbi_spec_is_0_1())
    > + pr_info("SBI implementation ID=0x%lx Version=0x%lx\n",
    > + sbi_get_firmware_id(), sbi_get_firmware_version());
    > +}
    > diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
    > index a990a6cb184f..abf2b9ee5307 100644
    > --- a/arch/riscv/kernel/setup.c
    > +++ b/arch/riscv/kernel/setup.c
    > @@ -21,6 +21,7 @@
    > #include <asm/sections.h>
    > #include <asm/pgtable.h>
    > #include <asm/smp.h>
    > +#include <asm/sbi.h>
    > #include <asm/tlbflush.h>
    > #include <asm/thread_info.h>
    >
    > @@ -70,6 +71,7 @@ void __init setup_arch(char **cmdline_p)
    > swiotlb_init(1);
    > #endif
    >
    > + sbi_init();
    > #ifdef CONFIG_SMP
    > setup_smp();
    > #endif
    > --
    > 2.21.0
    >

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