Commit 264969b4 authored by Sean Christopherson's avatar Sean Christopherson
Browse files

KVM: x86: Add a macro to precisely handle aliased 0x1.EDX CPUID features 

Add a macro to precisely handle CPUID features that AMD duplicated from
CPUID.0x1.EDX into CPUID.0x8000_0001.EDX.  This will allow adding an
assert that all features passed to kvm_cpu_cap_init() match the word being
processed, e.g. to prevent passing a feature from CPUID 0x7 to CPUID 0x1.

Because the kernel simply reuses the X86_FEATURE_* definitions from
CPUID.0x1.EDX, KVM's use of the aliased features would result in false
positives from such an assert.

No functional change intended.

Link: https://lore.kernel.org/r/20241128013424.4096668-26-seanjc@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent 6eac4d99

arch/x86/kvm/cpuid.c

+29 −18
Original line number Diff line number Diff line
@@ -669,6 +669,16 @@ static __always_inline void kvm_cpu_cap_init(enum cpuid_leafs leaf, u32 mask) 
	(IS_ENABLED(CONFIG_X86_64) ? F(name) : 0);		\

})



/*

 * Aliased Features - For features in 0x8000_0001.EDX that are duplicates of

 * identical 0x1.EDX features, and thus are aliased from 0x1 to 0x8000_0001.

 */

#define ALIASED_1_EDX_F(name)							\

({										\

	BUILD_BUG_ON(__feature_leaf(X86_FEATURE_##name) != CPUID_1_EDX);	\

	feature_bit(name);							\

})



void kvm_set_cpu_caps(void)

{

	memset(kvm_cpu_caps, 0, sizeof(kvm_cpu_caps));
@@ -913,30 +923,30 @@ void kvm_set_cpu_caps(void) 
	);



	kvm_cpu_cap_init(CPUID_8000_0001_EDX,

		F(FPU) |

		F(VME) |

		F(DE) |

		F(PSE) |

		F(TSC) |

		F(MSR) |

		F(PAE) |

		F(MCE) |

		F(CX8) |

		F(APIC) |

		ALIASED_1_EDX_F(FPU) |

		ALIASED_1_EDX_F(VME) |

		ALIASED_1_EDX_F(DE) |

		ALIASED_1_EDX_F(PSE) |

		ALIASED_1_EDX_F(TSC) |

		ALIASED_1_EDX_F(MSR) |

		ALIASED_1_EDX_F(PAE) |

		ALIASED_1_EDX_F(MCE) |

		ALIASED_1_EDX_F(CX8) |

		ALIASED_1_EDX_F(APIC) |

		0 /* Reserved */ |

		F(SYSCALL) |

		F(MTRR) |

		F(PGE) |

		F(MCA) |

		F(CMOV) |

		F(PAT) |

		F(PSE36) |

		ALIASED_1_EDX_F(MTRR) |

		ALIASED_1_EDX_F(PGE) |

		ALIASED_1_EDX_F(MCA) |

		ALIASED_1_EDX_F(CMOV) |

		ALIASED_1_EDX_F(PAT) |

		ALIASED_1_EDX_F(PSE36) |

		0 /* Reserved */ |

		F(NX) |

		0 /* Reserved */ |

		F(MMXEXT) |

		F(MMX) |

		F(FXSR) |

		ALIASED_1_EDX_F(MMX) |

		ALIASED_1_EDX_F(FXSR) |

		F(FXSR_OPT) |

		X86_64_F(GBPAGES) |

		F(RDTSCP) |
@@ -1076,6 +1086,7 @@ EXPORT_SYMBOL_GPL(kvm_set_cpu_caps); 
#undef F

#undef SF

#undef X86_64_F

#undef ALIASED_1_EDX_F



struct kvm_cpuid_array {

	struct kvm_cpuid_entry2 *entries;