[v2,2/8] KVM: x86: SVM: Set EMULTYPE_NO_REEXECUTE for RSM emulation
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Message ID 20180823205653.3264-3-sean.j.christopherson@intel.com
State New
Headers show
  • KVM: x86: Fix the emulation type mess
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Commit Message

Sean Christopherson Aug. 23, 2018, 8:56 p.m. UTC
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

Fixes: 7607b7174405 ("KVM: SVM: install RSM intercept")
Cc: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
 arch/x86/include/asm/kvm_host.h | 7 +++++++
 arch/x86/kvm/svm.c              | 4 ++--
 2 files changed, 9 insertions(+), 2 deletions(-)

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diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 00ddb0c9e612..3b220b86c8e4 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1251,6 +1251,13 @@  static inline int emulate_instruction(struct kvm_vcpu *vcpu,
 			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);
 bool kvm_valid_efer(struct kvm_vcpu *vcpu, u64 efer);
 int kvm_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr);
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 6276140044d0..f50c6ecffad9 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -3874,8 +3874,8 @@  static int emulate_on_interception(struct vcpu_svm *svm)
 static int rsm_interception(struct vcpu_svm *svm)
-	return x86_emulate_instruction(&svm->vcpu, 0, 0,
-				       rsm_ins_bytes, 2) == EMULATE_DONE;
+	return kvm_emulate_instruction_from_buffer(&svm->vcpu,
+					rsm_ins_bytes, 2) == EMULATE_DONE;
 static int rdpmc_interception(struct vcpu_svm *svm)