x86/cpufeatures: Re-enable ENQCMD

mainline inclusion
from mainline-v5.18
commit 7c1ef591
category: feature
bugzilla: https://gitee.com/openeuler/intel-kernel/issues/I596WO
CVE: NA

Intel-SIG: commit 7c1ef591 x86/cpufeatures: Re-enable ENQCMD.
Incremental backporting patches for DSA/IAA on Intel Xeon platform.

--------------------------------

The ENQCMD feature can only be used if CONFIG_INTEL_IOMMU_SVM is set.
Add X86_FEATURE_ENQCMD to the disabled features mask as appropriate so
that cpu_feature_enabled() can be used to check the feature.

  [ bp: Massage commit message. ]
Signed-off-by: NFenghua Yu <fenghua.yu@intel.com>
Signed-off-by: NBorislav Petkov <bp@suse.de>
Reviewed-by: NTony Luck <tony.luck@intel.com>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20220207230254.3342514-10-fenghua.yu@intel.comSigned-off-by: NXiaochen Shen <xiaochen.shen@intel.com>

arch/x86/include/asm/disabled-features.h

@@ -75,8 +75,11 @@
 # define DISABLE_UNRET		(1 << (X86_FEATURE_UNRET & 31))
 #endif
 
-/* Force disable because it's broken beyond repair */
-#define DISABLE_ENQCMD		(1 << (X86_FEATURE_ENQCMD & 31))
+#ifdef CONFIG_INTEL_IOMMU_SVM
+# define DISABLE_ENQCMD		0
+#else
+# define DISABLE_ENQCMD		(1 << (X86_FEATURE_ENQCMD & 31))
+#endif
 
 #ifdef CONFIG_X86_SGX
 # define DISABLE_SGX	0