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

[Jiri Denemark]

On Thu, Apr 09, 2020 at 11:28:04 +0100, Daniel P. Berrangé wrote:
> On Thu, Apr 02, 2020 at 05:03:59PM +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(-)
> > 
> > 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>
> >  
> >  #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)
> 
> virCPUarmDataFromRegs()
> 
> > +{
> > +    /* 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"};
> > +    unsigned long cpuid, hwcaps;
> > +    char **features = NULL;
> > +    char *cpu_feature_str = NULL;
> 
> g_autofree
> 
> > +    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;
> > +        }
> 
> Indent messed up here
> 
> > +
> > +    /* 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++;
> > +            }
> > +        }
> 
> Indent of } messed up again.
> 
> > +
> > +    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:
> 
> This should be called "error", since this label is only
> visited for fatal errors.
> 
> > +    virStringListFree(features);
> > +    VIR_FREE(cpu_feature_str);
> 
> Can avoid the VIR_FREE with g_autofree.

virStringListFree can be avoided too if features is declared with
VIR_AUTOSTRINGLIST.

Jirka