Commit 8cb4a9a8 authored by Sean Christopherson's avatar Sean Christopherson Committed by Linus Torvalds
Browse files

x86/cpufeatures: Add CPUID_LNX_5 to track recently added Linux-defined word 



Add CPUID_LNX_5 to track cpufeatures' word 21, and add the appropriate
compile-time assert in KVM to prevent direct lookups on the features in
CPUID_LNX_5.  KVM uses X86_FEATURE_* flags to manage guest CPUID, and so
must translate features that are scattered by Linux from the Linux-defined
bit to the hardware-defined bit, i.e. should never try to directly access
scattered features in guest CPUID.

Opportunistically add NR_CPUID_WORDS to enum cpuid_leafs, along with a
compile-time assert in KVM's CPUID infrastructure to ensure that future
additions update cpuid_leafs along with NCAPINTS.

No functional change intended.

Fixes: 7f274e60 ("x86/cpufeatures: Add new word for scattered features")
Cc: Sandipan Das <sandipan.das@amd.com>
Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Acked-by: default avatarDave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent c88b9b4c

arch/x86/include/asm/cpufeature.h

+2 −0
Original line number Diff line number Diff line
@@ -33,6 +33,8 @@ enum cpuid_leafs 
	CPUID_7_EDX,

	CPUID_8000_001F_EAX,

	CPUID_8000_0021_EAX,

	CPUID_LNX_5,

	NR_CPUID_WORDS,

};



#define X86_CAP_FMT_NUM "%d:%d"

arch/x86/kvm/reverse_cpuid.h

+2 −0
Original line number Diff line number Diff line
@@ -102,10 +102,12 @@ static const struct cpuid_reg reverse_cpuid[] = { 
 */

static __always_inline void reverse_cpuid_check(unsigned int x86_leaf)

{

	BUILD_BUG_ON(NR_CPUID_WORDS != NCAPINTS);

	BUILD_BUG_ON(x86_leaf == CPUID_LNX_1);

	BUILD_BUG_ON(x86_leaf == CPUID_LNX_2);

	BUILD_BUG_ON(x86_leaf == CPUID_LNX_3);

	BUILD_BUG_ON(x86_leaf == CPUID_LNX_4);

	BUILD_BUG_ON(x86_leaf == CPUID_LNX_5);

	BUILD_BUG_ON(x86_leaf >= ARRAY_SIZE(reverse_cpuid));

	BUILD_BUG_ON(reverse_cpuid[x86_leaf].function == 0);

}