[PATCH V2 5/5] cpu: Introduce getHost support for ARM CPU driver

[Jiri Denemark]

On Thu, Apr 02, 2020 at 17:03:59 +0800, Zhenyu Zheng wrote:
> Introduce getHost support for ARM CPU driver, read
> CPU vendor_id, part_id and flags from registers
> directly.
> 
> Signed-off-by: Zhenyu Zheng <zhengzhenyulixi at gmail.com>
> ---
>  src/cpu/cpu_arm.c | 194 +++++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 193 insertions(+), 1 deletion(-)

In addition to all the coding style issues which Daniel pointed out...

> diff --git a/src/cpu/cpu_arm.c b/src/cpu/cpu_arm.c
> index 88b4d91946..c8f5ce7e8a 100644
> --- a/src/cpu/cpu_arm.c
> +++ b/src/cpu/cpu_arm.c
> @@ -21,6 +21,8 @@
>   */
>  
>  #include <config.h>
> +#include <asm/hwcap.h>
> +#include <sys/auxv.h>

None of these header files exist on my system with linux 5.6 headers.

>  #include "viralloc.h"
>  #include "cpu.h"
> @@ -31,6 +33,10 @@
>  #include "virxml.h"
>  
>  #define VIR_FROM_THIS VIR_FROM_CPU
> +/* Shift bit mask for parsing cpu flags */
> +#define BIT_SHIFTS(n) (1UL << (n))
> +/* The current max number of cpu flags on ARM is 32 */
> +#define MAX_CPU_FLAGS 32
>  
>  VIR_LOG_INIT("cpu.cpu_arm");
>  
> @@ -498,14 +504,200 @@ virCPUarmValidateFeatures(virCPUDefPtr cpu)
>      return 0;
>  }
>  
> +/**
> + * armCpuDataFromRegs:
> + *
> + * @data: 64-bit arm CPU specific data
> + *
> + * Fetches CPU vendor_id and part_id from MIDR_EL1 register, parse CPU
> + * flags from AT_HWCAP. There are currently 32 valid flags  on ARM arch
> + * represented by each bit.
> + */
> +static int
> +armCpuDataFromRegs(virCPUarmData *data)
> +{
> +    /* Generate human readable flag list according to the order of */
> +    /* AT_HWCAP bit map */
> +    const char *flag_list[MAX_CPU_FLAGS] = {
> +        "fp", "asimd", "evtstrm", "aes", "pmull", "sha1", "sha2",
> +        "crc32", "atomics", "fphp", "asimdhp", "cpuid", "asimdrdm",
> +        "jscvt", "fcma", "lrcpc", "dcpop", "sha3", "sm3", "sm4",
> +        "asimddp", "sha512", "sve", "asimdfhm", "dit", "uscat",
> +        "ilrcpc", "flagm", "ssbs", "sb", "paca", "pacg"};

I would expect these to be defined in src/cpu_map/arm_features.xml,
although I'm not sure how well the new features would play with the
existing ones... What do you think, Andrea?

> +    unsigned long cpuid, hwcaps;
> +    char **features = NULL;
> +    char *cpu_feature_str = NULL;
> +    int cpu_feature_index = 0;
> +    size_t i;
> +
> +    if (!(getauxval(AT_HWCAP) & HWCAP_CPUID)) {
> +        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> +                       _("CPUID registers unavailable"));
> +            return -1;
> +        }
> +
> +    /* read the cpuid data from MIDR_EL1 register */
> +    asm("mrs %0, MIDR_EL1" : "=r" (cpuid));
> +    VIR_DEBUG("CPUID read from register:  0x%016lx", cpuid);
> +
> +    /* parse the coresponding part_id bits */
> +    data->pvr = cpuid>>4&0xFFF;
> +    /* parse the coresponding vendor_id bits */
> +    data->vendor_id = cpuid>>24&0xFF;
> +
> +    hwcaps = getauxval(AT_HWCAP);
> +    VIR_DEBUG("CPU flags read from register:  0x%016lx", hwcaps);
> +
> +    if (VIR_ALLOC_N(features, MAX_CPU_FLAGS) < 0)
> +        return -1;
> +
> +    /* shift bit map mask to parse for CPU flags */
> +    for (i = 0; i< MAX_CPU_FLAGS; i++) {
> +        if (hwcaps & BIT_SHIFTS(i)) {
> +            features[cpu_feature_index] = g_strdup(flag_list[i]);
> +            cpu_feature_index++;
> +            }
> +        }
> +
> +    if (cpu_feature_index > 1) {
> +        cpu_feature_str = virStringListJoin((const char **)features, " ");
> +        if (!cpu_feature_str)
> +            goto cleanup;
> +    }
> +    data->features = g_strdup(cpu_feature_str);
> +
> +    return 0;
> +
> + cleanup:
> +    virStringListFree(features);
> +    VIR_FREE(cpu_feature_str);
> +    return -1;
> +}
> +
> +static int
> +armCpuDataParseFeatures(virCPUDefPtr cpu,
> +                        const virCPUarmData *cpuData)
> +{
> +    int ret = -1;
> +    size_t i;
> +    char **features;
> +
> +    if (!cpu || !cpuData)
> +        return ret;
> +
> +    if (!(features = virStringSplitCount(cpuData->features, " ",
> +                                         0, &cpu->nfeatures)))
> +        return ret;
> +    if (cpu->nfeatures) {
> +        if (VIR_ALLOC_N(cpu->features, cpu->nfeatures) < 0)
> +            goto error;
> +
> +        for (i = 0; i < cpu->nfeatures; i++) {
> +            cpu->features[i].policy = VIR_CPU_FEATURE_REQUIRE;
> +            cpu->features[i].name = g_strdup(features[i]);
> +        }
> +    }
> +
> +    ret = 0;
> +
> + cleanup:
> +    virStringListFree(features);
> +    return ret;
> +
> + error:
> +    for (i = 0; i < cpu->nfeatures; i++)
> +        VIR_FREE(cpu->features[i].name);
> +    VIR_FREE(cpu->features);
> +    cpu->nfeatures = 0;
> +    goto cleanup;
> +}
> +
> +static int
> +armDecode(virCPUDefPtr cpu,
> +          const virCPUarmData *cpuData,
> +          virDomainCapsCPUModelsPtr models)
> +{
> +    virCPUarmMapPtr map;
> +    virCPUarmModelPtr model;
> +    virCPUarmVendorPtr vendor = NULL;
> +
> +    if (!cpuData || !(map = virCPUarmGetMap()))
> +        return -1;
> +
> +    if (!(model = armModelFindByPVR(map, cpuData->pvr))) {
> +        virReportError(VIR_ERR_OPERATION_FAILED,
> +                       _("Cannot find CPU model with PVR 0x%03lx"),
> +                       cpuData->pvr);
> +        return -1;
> +    }
> +
> +    if (!virCPUModelIsAllowed(model->name, models)) {
> +        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
> +                       _("CPU model %s is not supported by hypervisor"),
> +                       model->name);
> +        return -1;
> +    }
> +
> +    cpu->model = g_strdup(model->name);
> +
> +    if (cpuData->vendor_id &&
> +        !(vendor = armVendorFindByID(map, cpuData->vendor_id))) {
> +        virReportError(VIR_ERR_OPERATION_FAILED,
> +                       _("Cannot find CPU vendor with vendor id 0x%02lx"),
> +                       cpuData->vendor_id);
> +        return -1;
> +    }
> +
> +    if (vendor)
> +        cpu->vendor = g_strdup(vendor->name);
> +
> +    if (cpuData->features &&
> +        armCpuDataParseFeatures(cpu, cpuData) < 0)
> +        return -1;
> +
> +    return 0;
> +}
> +
> +static int
> +armDecodeCPUData(virCPUDefPtr cpu,
> +                 const virCPUData *data,
> +                 virDomainCapsCPUModelsPtr models)
> +{
> +    return armDecode(cpu, &data->data.arm, models);
> +}
> +
> +static int
> +virCPUarmGetHost(virCPUDefPtr cpu,
> +                 virDomainCapsCPUModelsPtr models)
> +{
> +    virCPUDataPtr cpuData = NULL;
> +    int ret = -1;
> +
> +    if (virCPUarmDriverInitialize() < 0)
> +        goto cleanup;
> +
> +    if (!(cpuData = virCPUDataNew(archs[0])))
> +        goto cleanup;
> +
> +    if (armCpuDataFromRegs(&cpuData->data.arm) < 0)
> +        goto cleanup;
> +
> +    ret = armDecodeCPUData(cpu, cpuData, models);
> +
> + cleanup:
> +    virCPUarmDataFree(cpuData);
> +    return ret;
> +}

virCPUarmGetHost and the helpers it calls are architecture specific and
should not be even compiled in on non-ARM.

Jirka