Commit 855c7e9b authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: x86: Fix BUILD_BUG() in __cpuid_entry_get_reg() w/ CONFIG_UBSAN=y 



Take the target reg in __cpuid_entry_get_reg() instead of a pointer to a
struct cpuid_reg.  When building with -fsanitize=alignment (enabled by
CONFIG_UBSAN=y), some versions of gcc get tripped up on the pointer and
trigger the BUILD_BUG().

Reported-by: default avatarRandy Dunlap <rdunlap@infradead.org>
Fixes: d8577a4c ("KVM: x86: Do host CPUID at load time to mask KVM cpu caps")
Fixes: 4c61534a ("KVM: x86: Introduce cpuid_entry_{get,has}() accessors")
Signed-off-by: default avatarSean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200325191259.23559-1-sean.j.christopherson@intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 842f4be9

arch/x86/kvm/cpuid.c

+1 −1
Original line number Diff line number Diff line
@@ -269,7 +269,7 @@ static __always_inline void kvm_cpu_cap_mask(enum cpuid_leafs leaf, u32 mask) 
	cpuid_count(cpuid.function, cpuid.index,

		    &entry.eax, &entry.ebx, &entry.ecx, &entry.edx);



	kvm_cpu_caps[leaf] &= *__cpuid_entry_get_reg(&entry, &cpuid);

	kvm_cpu_caps[leaf] &= *__cpuid_entry_get_reg(&entry, cpuid.reg);

}



void kvm_set_cpu_caps(void)

arch/x86/kvm/cpuid.h

+4 −4
Original line number Diff line number Diff line
@@ -99,9 +99,9 @@ static __always_inline struct cpuid_reg x86_feature_cpuid(unsigned int x86_featu 
}



static __always_inline u32 *__cpuid_entry_get_reg(struct kvm_cpuid_entry2 *entry,

						  const struct cpuid_reg *cpuid)

						  u32 reg)

{

	switch (cpuid->reg) {

	switch (reg) {

	case CPUID_EAX:

		return &entry->eax;

	case CPUID_EBX:
@@ -121,7 +121,7 @@ static __always_inline u32 *cpuid_entry_get_reg(struct kvm_cpuid_entry2 *entry, 
{

	const struct cpuid_reg cpuid = x86_feature_cpuid(x86_feature);



	return __cpuid_entry_get_reg(entry, &cpuid);

	return __cpuid_entry_get_reg(entry, cpuid.reg);

}



static __always_inline u32 cpuid_entry_get(struct kvm_cpuid_entry2 *entry,
@@ -189,7 +189,7 @@ static __always_inline u32 *guest_cpuid_get_register(struct kvm_vcpu *vcpu, 
	if (!entry)

		return NULL;



	return __cpuid_entry_get_reg(entry, &cpuid);

	return __cpuid_entry_get_reg(entry, cpuid.reg);

}



static __always_inline bool guest_cpuid_has(struct kvm_vcpu *vcpu,

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