On 7 December 2016 at 17:06, <vijay.kil...@gmail.com> wrote:
> From: Vijaya Kumar K <vijaya.ku...@cavium.com>
>
> Add helper API to read MIDR_EL1 registers to fetch
> cpu identification information. This helps in
> adding errata's and architecture specific features.
>
> This is implemented only for arm architecture.
>
> Signed-off-by: Vijaya Kumar K <vijaya.ku...@cavium.com>
> ---
> include/qemu/aarch64-cpuid.h | 38 ++++++++++++++++++++++++++++++++
> util/Makefile.objs | 1 +
> util/aarch64-cpuid.c | 52
> ++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 91 insertions(+)
>
> diff --git a/include/qemu/aarch64-cpuid.h b/include/qemu/aarch64-cpuid.h
> new file mode 100644
> index 0000000..fb88ed8
> --- /dev/null
> +++ b/include/qemu/aarch64-cpuid.h
> @@ -0,0 +1,38 @@
> +#ifndef QEMU_AARCH64_CPUID_H
> +#define QEMU_AARCH64_CPUID_H
> +
> +#if defined(__aarch64__) && defined(CONFIG_LINUX)
> +#define MIDR_IMPLEMENTER_SHIFT 24
> +#define MIDR_IMPLEMENTER_MASK (0xffULL << MIDR_IMPLEMENTER_SHIFT)
> +#define MIDR_ARCHITECTURE_SHIFT 16
> +#define MIDR_ARCHITECTURE_MASK (0xf << MIDR_ARCHITECTURE_SHIFT)
> +#define MIDR_PARTNUM_SHIFT 4
> +#define MIDR_PARTNUM_MASK (0xfff << MIDR_PARTNUM_SHIFT)
> +
> +#define MIDR_CPU_PART(imp, partnum) \
> + (((imp) << MIDR_IMPLEMENTER_SHIFT) | \
> + (0xf << MIDR_ARCHITECTURE_SHIFT) | \
> + ((partnum) << MIDR_PARTNUM_SHIFT))
> +
> +#define ARM_CPU_IMP_CAVIUM 0x43
> +#define CAVIUM_CPU_PART_THUNDERX 0x0A1
> +
> +#define MIDR_THUNDERX_PASS2 \
> + MIDR_CPU_PART(ARM_CPU_IMP_CAVIUM, CAVIUM_CPU_PART_THUNDERX)
> +#define CPU_MODEL_MASK (MIDR_IMPLEMENTER_MASK | MIDR_ARCHITECTURE_MASK | \
> + MIDR_PARTNUM_MASK)
> +
> +uint64_t get_aarch64_cpu_id(void);
> +bool is_thunderx_pass2_cpu(void);
> +#else
> +static inline uint64_t get_aarch64_cpu_id(void)
> +{
> + return 0;
> +}
> +
> +static inline bool is_thunderx_pass2_cpu(void)
> +{
> + return false;
> +}
> +#endif
> +#endif
> diff --git a/util/Makefile.objs b/util/Makefile.objs
> index ad0f9c7..a9585c9 100644
> --- a/util/Makefile.objs
> +++ b/util/Makefile.objs
> @@ -36,3 +36,4 @@ util-obj-y += log.o
> util-obj-y += qdist.o
> util-obj-y += qht.o
> util-obj-y += range.o
> +util-obj-$(CONFIG_LINUX) += aarch64-cpuid.o
> diff --git a/util/aarch64-cpuid.c b/util/aarch64-cpuid.c
> new file mode 100644
> index 0000000..575f52e
> --- /dev/null
> +++ b/util/aarch64-cpuid.c
> @@ -0,0 +1,52 @@
> +/*
> + * Dealing with arm cpu identification information.
> + *
> + * Copyright (C) 2016 Cavium, Inc.
> + *
> + * Authors:
> + * Vijaya Kumar K <vijaya.ku...@cavium.com>
> + *
> + * This work is licensed under the terms of the GNU LGPL, version 2.1
> + * or later. See the COPYING.LIB file in the top-level directory.
> + */
> +
> +#include "qemu/osdep.h"
> +#include "qemu/cutils.h"
> +#include "qemu/aarch64-cpuid.h"
> +
> +#if defined(__aarch64__)
> +static uint64_t qemu_read_aarch64_midr_el1(void)
> +{
> + const char *file =
> "/sys/devices/system/cpu/cpu0/regs/identification/midr_el1";
If CPU0 happens to be offline (eg hot-unplugged) then this file
won't exist, and we'll fail to identify any MIDR value.
The API as designed here also doesn't seem to consider
the idea of big.LITTLE systems -- if there are multiple
CPUs with different MIDRs, which one should we return here?
> + char *buf;
> + uint64_t midr = 0;
> +
> + if (!g_file_get_contents(file, &buf, 0, NULL)) {
> + goto out;
> + }
> +
> + if (qemu_strtoull(buf, NULL, 0, &midr) < 0) {
> + midr = 0;
> + goto out;
> + }
> +
> +out:
> + g_free(buf);
> +
> + return midr;
thanks
-- PMM
