Re: [Xen-devel] [PATCH v2 03/10] libx86: Introduce x86_cpu_policies_are_compatible()

[Jan Beulich <jbeulich@suse.com>]

On 13.09.2019 21:27, Andrew Cooper wrote:
> --- /dev/null
> +++ b/xen/lib/x86/policy.c
> @@ -0,0 +1,54 @@
> +#include "private.h"
> +
> +#include <xen/lib/x86/cpu-policy.h>
> +
> +int x86_cpu_policies_are_compatible(const struct cpu_policy *host,
> +                                    const struct cpu_policy *guest,
> +                                    struct cpu_policy_errors *err)
> +{
> +    struct cpu_policy_errors e = INIT_CPU_POLICY_ERRORS;
> +    int ret = -EINVAL;
> +
> +    if ( err )
> +        *err = e;

You don't really need this, do you? All paths lead ...

> +#define NA XEN_CPUID_NO_SUBLEAF
> +#define FAIL_CPUID(l, s) \
> +    do { e.leaf = (l); e.subleaf = (s); goto out; } while ( 0 )
> +#define FAIL_MSR(m) \
> +    do { e.msr = (m); goto out; } while ( 0 )
> +
> +    if ( guest->cpuid->basic.max_leaf > host->cpuid->basic.max_leaf )
> +        FAIL_CPUID(0, NA);
> +
> +    if ( guest->cpuid->extd.max_leaf > host->cpuid->extd.max_leaf )
> +        FAIL_CPUID(0x80000008, NA);
> +
> +    /* TODO: Audit more CPUID data. */
> +
> +    if ( ~host->msr->platform_info.raw & guest->msr->platform_info.raw )
> +        FAIL_MSR(MSR_INTEL_PLATFORM_INFO);
> +
> +#undef FAIL_MSR
> +#undef FAIL_CPUID
> +#undef NA
> +
> +    /* Success. */
> +    ret = 0;
> +
> + out:
> +    if ( ret && err )
> +        *err = e;

... here, and hence you could simply drop the "ret &&" part of the
condition.

Jan

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