Re: [Xen-devel] [PATCH v8 1/7] x86/domctl: generalize the restore of vMCE parameters

["Jan Beulich" <jbeulich@xxxxxxxx>]

>>> Haozhong Zhang <haozhong.zhang@xxxxxxxxx> 07/10/17 4:53 AM >>>
>--- a/xen/arch/x86/domctl.c
>+++ b/xen/arch/x86/domctl.c
>@@ -302,6 +302,42 @@ static int update_domain_cpuid_info(struct domain *d,
     >return 0;
 >}
 >
>+static int vcpu_set_vmce(struct vcpu *v,
>+                         const struct xen_domctl_ext_vcpucontext *evc)
>+{
>+    /*
>+     * Sizes of vMCE parameters used by the current and past versions
>+     * of Xen in descending order. If vMCE parameters are extended,
>+     * remember to add the old size to this array by VMCE_SIZE().
>+     */
>+#define VMCE_SIZE(param) \

I dislike macro (or function) parameter to be named "param" or alike. Please
use names that say what they stand for, e.g. "field" here.

>+    (offsetof(typeof(evc->vmce), param) + sizeof(evc->vmce.param))
>+
>+    static const unsigned int valid_sizes[] = {
>+        sizeof(evc->vmce),
>+        VMCE_SIZE(caps),
>+    };
>+#undef VMCE_SIZE
>+
>+    struct hvm_vmce_vcpu vmce = { };
>+    unsigned int evc_vmce_size = evc->size - offsetof(typeof(*evc), mcg_cap);

I'd prefer for this to be put in a min(..., sizeof(evc->vmce)) to cope with
possible future additions of members after the vmce one.

Jan


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