Commit 49def500 authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
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KVM: VMX: Read cached VM-Exit reason to detect external interrupt 



Generic x86 code invokes the kvm_x86_ops external interrupt handler on
all VM-Exits regardless of the actual exit type.  Use the already-cached
EXIT_REASON to determine if the VM-Exit was due to an interrupt, thus
avoiding an extra VMREAD (to query VM_EXIT_INTR_INFO) for all other
types of VM-Exit.

In addition to avoiding the extra VMREAD, checking the EXIT_REASON
instead of VM_EXIT_INTR_INFO makes it more obvious that
vmx_handle_external_intr() is called for all VM-Exits, e.g. someone
unfamiliar with the flow might wonder under what condition(s)
VM_EXIT_INTR_INFO does not contain a valid interrupt, which is
simply not possible since KVM always runs with "ack interrupt on exit".

WARN once if VM_EXIT_INTR_INFO doesn't contain a valid interrupt on
an EXTERNAL_INTERRUPT VM-Exit, as such a condition would indicate a
hardware bug.

Signed-off-by: default avatarSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 2ea72039

arch/x86/kvm/vmx/vmcs.h

+6 −0
Original line number Diff line number Diff line
@@ -115,6 +115,12 @@ static inline bool is_nmi(u32 intr_info) 
		== (INTR_TYPE_NMI_INTR | INTR_INFO_VALID_MASK);

}



static inline bool is_external_intr(u32 intr_info)

{

	return (intr_info & (INTR_INFO_VALID_MASK | INTR_INFO_INTR_TYPE_MASK))

		== (INTR_INFO_VALID_MASK | INTR_TYPE_EXT_INTR);

}



enum vmcs_field_width {

	VMCS_FIELD_WIDTH_U16 = 0,

	VMCS_FIELD_WIDTH_U64 = 1,

arch/x86/kvm/vmx/vmx.c

+33 −29
Original line number Diff line number Diff line
@@ -6127,21 +6127,26 @@ static void vmx_complete_atomic_exit(struct vcpu_vmx *vmx) 


static void vmx_handle_external_intr(struct kvm_vcpu *vcpu)

{

	u32 exit_intr_info = vmcs_read32(VM_EXIT_INTR_INFO);



	if ((exit_intr_info & (INTR_INFO_VALID_MASK | INTR_INFO_INTR_TYPE_MASK))

			== (INTR_INFO_VALID_MASK | INTR_TYPE_EXT_INTR)) {

	unsigned int vector;

	unsigned long entry;

		gate_desc *desc;

		struct vcpu_vmx *vmx = to_vmx(vcpu);

#ifdef CONFIG_X86_64

	unsigned long tmp;

#endif

	gate_desc *desc;

	u32 intr_info;



		vector =  exit_intr_info & INTR_INFO_VECTOR_MASK;

	if (to_vmx(vcpu)->exit_reason != EXIT_REASON_EXTERNAL_INTERRUPT)

		return;



	intr_info = vmcs_read32(VM_EXIT_INTR_INFO);

	if (WARN_ONCE(!is_external_intr(intr_info),

	    "KVM: unexpected VM-Exit interrupt info: 0x%x", intr_info))

		return;



	vector = intr_info & INTR_INFO_VECTOR_MASK;

	desc = (gate_desc *)vmx->host_idt_base + vector;

	entry = gate_offset(desc);



	asm volatile(

#ifdef CONFIG_X86_64

		"mov %%" _ASM_SP ", %[sp]\n\t"
@@ -6163,7 +6168,6 @@ static void vmx_handle_external_intr(struct kvm_vcpu *vcpu) 
		[cs]"i"(__KERNEL_CS)

	);

}

}

STACK_FRAME_NON_STANDARD(vmx_handle_external_intr);



static bool vmx_has_emulated_msr(int index)

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