Re: [PATCH 19/24] KVM: x86 emulator: fix in/out emulation.

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On 03/09/2010 04:09 PM, Gleb Natapov wrote:
in/out emulation is broken now. The breakage is different depending
on where IO device resides. If it is in userspace emulator reports
emulation failure since it incorrectly interprets kvm_emulate_pio()
return value. If IO device is in the kernel emulation of 'in' will do
nothing since kvm_emulate_pio() stores result directly into vcpu
registers, so emulator will overwrite result of emulation during
commit of shadowed register.


index def4877..315e8a8 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1488,29 +1488,9 @@ static int shutdown_interception(struct vcpu_svm *svm)

  static int io_interception(struct vcpu_svm *svm)
  {
-	u32 io_info = svm->vmcb->control.exit_info_1; /* address size bug? */
-	int size, in, string;
-	unsigned port;
-
  	++svm->vcpu.stat.io_exits;

-	svm->next_rip = svm->vmcb->control.exit_info_2;
-
-	string = (io_info&  SVM_IOIO_STR_MASK) != 0;
-
-	if (string) {
-		if (emulate_instruction(&svm->vcpu,
-					0, 0, 0) == EMULATE_DO_MMIO)
-			return 0;
-		return 1;
-	}
-
-	in = (io_info&  SVM_IOIO_TYPE_MASK) != 0;
-	port = io_info>>  16;
-	size = (io_info&  SVM_IOIO_SIZE_MASK)>>  SVM_IOIO_SIZE_SHIFT;
-
-	skip_emulated_instruction(&svm->vcpu);
-	return kvm_emulate_pio(&svm->vcpu, in, size, port);
+	return !(emulate_instruction(&svm->vcpu, 0, 0, 0) == EMULATE_DO_MMIO);
  }

We don't want to enter the emulator for non-string in/out. Leftover test code?


  static int nmi_interception(struct vcpu_svm *svm)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index ae3217d..7f33d8e 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2974,26 +2974,9 @@ static int handle_triple_fault(struct kvm_vcpu *vcpu)

  static int handle_io(struct kvm_vcpu *vcpu)
  {
-	unsigned long exit_qualification;
-	int size, in, string;
-	unsigned port;
-
  	++vcpu->stat.io_exits;
-	exit_qualification = vmcs_readl(EXIT_QUALIFICATION);
-	string = (exit_qualification&  16) != 0;

-	if (string) {
-		if (emulate_instruction(vcpu, 0, 0, 0) == EMULATE_DO_MMIO)
-			return 0;
-		return 1;
-	}
-
-	size = (exit_qualification&  7) + 1;
-	in = (exit_qualification&  8) != 0;
-	port = exit_qualification>>  16;
-
-	skip_emulated_instruction(vcpu);
-	return kvm_emulate_pio(vcpu, in, size, port);
+	return !(emulate_instruction(vcpu, 0, 0, 0) == EMULATE_DO_MMIO);
  }

Ditto.


--
error compiling committee.c: too many arguments to function

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