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KVM: x86: SVM: Set EMULTYPE_NO_REEXECUTE for RSM emulation

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Re-execution after an emulation decode failure is only intended to
handle a case where two or vCPUs race to write a shadowed page, i.e.
we should never re-execute an instruction as part of RSM emulation.

Add a new helper, kvm_emulate_instruction_from_buffer(), to support
emulating from a pre-defined buffer.  This eliminates the last direct
call to x86_emulate_instruction() outside of kvm_mmu_page_fault(),
which means x86_emulate_instruction() can be unexported in a future
patch.

Fixes: 7607b71744 ("KVM: SVM: install RSM intercept")
Cc: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
This commit is contained in:
Sean Christopherson
2018-08-23 13:56:47 -07:00
committed by Radim Krčmář
parent c4409905cd
commit 35be0aded7
2 changed files with 9 additions and 2 deletions
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7
arch/x86/include/asm/kvm_host.h
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@@ -1251,6 +1251,13 @@ static inline int emulate_instruction(struct kvm_vcpu *vcpu,
emulation_type | EMULTYPE_NO_REEXECUTE, NULL, 0); emulation_type | EMULTYPE_NO_REEXECUTE, 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, EMULTYPE_NO_REEXECUTE,
insn, insn_len);
}
void kvm_enable_efer_bits(u64); void kvm_enable_efer_bits(u64);
bool kvm_valid_efer(struct kvm_vcpu *vcpu, u64 efer); bool kvm_valid_efer(struct kvm_vcpu *vcpu, u64 efer);
int kvm_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr); int kvm_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr);

4
arch/x86/kvm/svm.c
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@@ -3874,8 +3874,8 @@ static int emulate_on_interception(struct vcpu_svm *svm)
static int rsm_interception(struct vcpu_svm *svm) static int rsm_interception(struct vcpu_svm *svm)
{ {
return x86_emulate_instruction(&svm->vcpu, 0, 0, return kvm_emulate_instruction_from_buffer(&svm->vcpu,
rsm_ins_bytes, 2) == EMULATE_DONE; rsm_ins_bytes, 2) == EMULATE_DONE;
} }
static int rdpmc_interception(struct vcpu_svm *svm) static int rdpmc_interception(struct vcpu_svm *svm)