x86/platform/UV: Support UV4 socket address changes

Hello Mike Travis,

This is a semi-automatic email about new static checker warnings.

The patch 1de329c10d9f: "x86/platform/UV: Support UV4 socket address changes" from Apr 29, 2016, leads to the following Smatch complaint:

arch/x86/kernel/apic/x2apic_uv_x.c:1201 decode_uv_systab()
error: we previously assumed 'st' could be null (see line 1199)

arch/x86/kernel/apic/x2apic_uv_x.c
1198 st = uv_systab;
1199 if ((!st || st->revision < UV_SYSTAB_VERSION_UV4) && !is_uv4_hub())

                      ^^

New check for NULL.

1200 return;

  1201		if (st->revision != UV_SYSTAB_VERSION_UV4_LATEST) {
                    ^^^^^^^^^^^^

Unchecked dereference in the is_uv4_hub() case. Perhaps the parenthesis are not in the right place or the check for NULL can be removed?

1202 pr_crit(
1203 "UV: BIOS UVsystab version(%x) mismatch, expecting(%x)\n",

regards,
dan carpenter