Commit c60658d1 authored by Sean Christopherson's avatar Sean Christopherson Committed by Radim Krčmář
Browse files

KVM: x86: Unexport x86_emulate_instruction() 



Allowing x86_emulate_instruction() to be called directly has led to
subtle bugs being introduced, e.g. not setting EMULTYPE_NO_REEXECUTE
in the emulation type.  While most of the blame lies on re-execute
being opt-out, exporting x86_emulate_instruction() also exposes its
cr2 parameter, which may have contributed to commit d391f120
("x86/kvm/vmx: do not use vm-exit instruction length for fast MMIO
when running nested") using x86_emulate_instruction() instead of
emulate_instruction() because "hey, I have a cr2!", which in turn
introduced its EMULTYPE_NO_REEXECUTE bug.

Signed-off-by: default avatarSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: default avatarRadim Krčmář <rkrcmar@redhat.com>
parent 0ce97a2b

arch/x86/include/asm/kvm_host.h

+3 −14
Original line number Diff line number Diff line
@@ -1240,20 +1240,9 @@ enum emulation_result { 
#define EMULTYPE_ALLOW_RETRY	    (1 << 3)

#define EMULTYPE_NO_UD_ON_FAIL	    (1 << 4)

#define EMULTYPE_VMWARE		    (1 << 5)

int x86_emulate_instruction(struct kvm_vcpu *vcpu, unsigned long cr2,

			    int emulation_type, void *insn, int insn_len);



static inline int kvm_emulate_instruction(struct kvm_vcpu *vcpu,

			int emulation_type)

{

	return x86_emulate_instruction(vcpu, 0, emulation_type, NULL, 0);

}



static inline int kvm_emulate_instruction_from_buffer(struct kvm_vcpu *vcpu,

						      void *insn, int insn_len)

{

	return x86_emulate_instruction(vcpu, 0, 0, insn, insn_len);

}

int kvm_emulate_instruction(struct kvm_vcpu *vcpu, int emulation_type);

int kvm_emulate_instruction_from_buffer(struct kvm_vcpu *vcpu,

					void *insn, int insn_len);



void kvm_enable_efer_bits(u64);

bool kvm_valid_efer(struct kvm_vcpu *vcpu, u64 efer);

arch/x86/kvm/x86.c

+13 −1
Original line number Diff line number Diff line
@@ -6282,7 +6282,19 @@ restart: 


	return r;

}

EXPORT_SYMBOL_GPL(x86_emulate_instruction);



int kvm_emulate_instruction(struct kvm_vcpu *vcpu, int emulation_type)

{

	return x86_emulate_instruction(vcpu, 0, emulation_type, NULL, 0);

}

EXPORT_SYMBOL_GPL(kvm_emulate_instruction);



int kvm_emulate_instruction_from_buffer(struct kvm_vcpu *vcpu,

					void *insn, int insn_len)

{

	return x86_emulate_instruction(vcpu, 0, 0, insn, insn_len);

}

EXPORT_SYMBOL_GPL(kvm_emulate_instruction_from_buffer);



static int kvm_fast_pio_out(struct kvm_vcpu *vcpu, int size,

			    unsigned short port)

arch/x86/kvm/x86.h

+2 −0
Original line number Diff line number Diff line
@@ -274,6 +274,8 @@ int kvm_mtrr_get_msr(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata); 
bool kvm_mtrr_check_gfn_range_consistency(struct kvm_vcpu *vcpu, gfn_t gfn,

					  int page_num);

bool kvm_vector_hashing_enabled(void);

int x86_emulate_instruction(struct kvm_vcpu *vcpu, unsigned long cr2,

			    int emulation_type, void *insn, int insn_len);



#define KVM_SUPPORTED_XCR0     (XFEATURE_MASK_FP | XFEATURE_MASK_SSE \

				| XFEATURE_MASK_YMM | XFEATURE_MASK_BNDREGS \

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