[libvirt] [PATCH v2 2/3] xenconfig: add conversions for xen-xl

[Jim Fehlig]

On 03/24/2017 03:02 PM, Wim Ten Have wrote:
> From: Wim ten Have <wim.ten.have at oracle.com>
>
> Per xen-xl conversions from and to native under host-passthrough
> mode we take care for Xen (nestedhvm = mode) applied and inherited
> settings generating or processing correct feature policy:
>
> [On Intel (VT-x) architectures]
> <feature policy='disable' name='vmx'/>
>
> or
>
> [On AMD (AMD-V) architectures]
> <feature policy='disable' name='svm'/>
>
> It will then generate (or parse) for nestedhvm=1 in/from xl format.
>
> Signed-off-by: Joao Martins <joao.m.martins at oracle.com>
> Signed-off-by: Wim ten Have <wim.ten.have at oracle.com>
> ---
>  src/xenconfig/xen_xl.c | 67 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 67 insertions(+)
>
> diff --git a/src/xenconfig/xen_xl.c b/src/xenconfig/xen_xl.c
> index 74f68b3..d3797b8 100644
> --- a/src/xenconfig/xen_xl.c
> +++ b/src/xenconfig/xen_xl.c
> @@ -106,6 +106,7 @@ xenParseXLOS(virConfPtr conf, virDomainDefPtr def, virCapsPtr caps)
>      if (def->os.type == VIR_DOMAIN_OSTYPE_HVM) {
>          const char *bios;
>          const char *boot;
> +        int val = 0;
>
>          if (xenConfigGetString(conf, "bios", &bios, NULL) < 0)
>              return -1;
> @@ -164,6 +165,47 @@ xenParseXLOS(virConfPtr conf, virDomainDefPtr def, virCapsPtr caps)
>              }
>              def->os.nBootDevs++;
>          }
> +
> +        if (xenConfigGetBool(conf, "nestedhvm", &val, -1) < 0)
> +            return -1;
> +
> +        if (val != -1) {
> +            virCPUDefPtr cpu = NULL;
> +
> +            if (VIR_ALLOC(cpu) < 0)
> +                return -1;
> +
> +            if (val == 0) {
> +                if (VIR_ALLOC_N(cpu->features, 2) < 0)
> +                    goto cleanup;
> +
> +                /*
> +                 * Below is pointless in real world but for purpose
> +                 * of testing let's check features depth holding at
> +                 * least multiple elements and also check if both
> +                 * vmx|svm are understood.
> +                 */
> +                cpu->features[0].policy = VIR_CPU_FEATURE_DISABLE;
> +                if (VIR_STRDUP(cpu->features[0].name, "vmx") < 0)
> +                    goto cleanup;
> +                cpu->features[1].policy = VIR_CPU_FEATURE_DISABLE;
> +                if (VIR_STRDUP(cpu->features[1].name, "svm") < 0)
> +                    goto cleanup;

Since caps is passed to this function, can it be used to determine whether to 
disable vmx or svm?

> +
> +                cpu->nfeatures = cpu->nfeatures_max = 2;
> +            }
> +            cpu->mode = VIR_CPU_MODE_HOST_PASSTHROUGH;
> +            cpu->type = VIR_CPU_TYPE_GUEST;
> +            def->cpu = cpu;
> +            cpu = NULL;
> + cleanup:
> +            if (cpu) {
> +                VIR_FREE(cpu->features);
> +                VIR_FREE(cpu);
> +                return -1;
> +            }

I'm not fond of the cleanup label in the middle of this function. If we can 
disable only one of vmx or svm, then there will be one less strdup and one less 
cleanup spot. Cleanup can then occur at the point of error.

> +        }
> +
>      } else {
>          if (xenConfigCopyStringOpt(conf, "bootloader", &def->os.bootloader) < 0)
>              return -1;
> @@ -897,6 +939,31 @@ xenFormatXLOS(virConfPtr conf, virDomainDefPtr def)
>          if (xenConfigSetString(conf, "boot", boot) < 0)
>              return -1;
>
> +        if (def->cpu &&
> +            def->cpu->mode == VIR_CPU_MODE_HOST_PASSTHROUGH) {
> +            bool hasHwVirt = true;
> +
> +            if (def->cpu->nfeatures) {
> +                for (i = 0; i < def->cpu->nfeatures; i++) {
> +
> +                    switch (def->cpu->features[i].policy) {
> +                        case VIR_CPU_FEATURE_DISABLE:
> +                        case VIR_CPU_FEATURE_FORBID:
> +                            if (STREQ(def->cpu->features[i].name, "vmx") ||
> +                                STREQ(def->cpu->features[i].name, "svm"))
> +                                hasHwVirt = false;
> +                            break;
> +
> +                        default:
> +                            break;

Similar to patch 1, replace 'default' with the other enum values.

Regards,
Jim

> +                    }
> +                }
> +            }
> +
> +            if (xenConfigSetInt(conf, "nestedhvm", hasHwVirt) < 0)
> +                return -1;
> +        }
> +
>          /* XXX floppy disks */
>      } else {
>          if (def->os.bootloader &&
>