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Commit 908a7bdd authored by Jan Kiszka's avatar Jan Kiszka Committed by Marcelo Tosatti
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KVM: nVMX: Improve I/O exit handling 



This prevents trapping L2 I/O exits if L1 has neither unconditional nor
bitmap-based exiting enabled. Furthermore, it implements I/O bitmap
handling.

Reviewed-by: default avatarGleb Natapov <gleb@redhat.com>
Signed-off-by: default avatarJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
parent 6b73a960

arch/x86/kvm/vmx.c

+47 −2
Original line number Diff line number Diff line
@@ -5908,6 +5908,52 @@ static int (*const kvm_vmx_exit_handlers[])(struct kvm_vcpu *vcpu) = { 
static const int kvm_vmx_max_exit_handlers =

	ARRAY_SIZE(kvm_vmx_exit_handlers);



static bool nested_vmx_exit_handled_io(struct kvm_vcpu *vcpu,

				       struct vmcs12 *vmcs12)

{

	unsigned long exit_qualification;

	gpa_t bitmap, last_bitmap;

	unsigned int port;

	int size;

	u8 b;



	if (nested_cpu_has(vmcs12, CPU_BASED_UNCOND_IO_EXITING))

		return 1;



	if (!nested_cpu_has(vmcs12, CPU_BASED_USE_IO_BITMAPS))

		return 0;



	exit_qualification = vmcs_readl(EXIT_QUALIFICATION);



	port = exit_qualification >> 16;

	size = (exit_qualification & 7) + 1;



	last_bitmap = (gpa_t)-1;

	b = -1;



	while (size > 0) {

		if (port < 0x8000)

			bitmap = vmcs12->io_bitmap_a;

		else if (port < 0x10000)

			bitmap = vmcs12->io_bitmap_b;

		else

			return 1;

		bitmap += (port & 0x7fff) / 8;



		if (last_bitmap != bitmap)

			if (kvm_read_guest(vcpu->kvm, bitmap, &b, 1))

				return 1;

		if (b & (1 << (port & 7)))

			return 1;



		port++;

		size--;

		last_bitmap = bitmap;

	}



	return 0;

}



/*

 * Return 1 if we should exit from L2 to L1 to handle an MSR access access,

 * rather than handle it ourselves in L0. I.e., check whether L1 expressed
@@ -6097,8 +6143,7 @@ static bool nested_vmx_exit_handled(struct kvm_vcpu *vcpu) 
	case EXIT_REASON_DR_ACCESS:

		return nested_cpu_has(vmcs12, CPU_BASED_MOV_DR_EXITING);

	case EXIT_REASON_IO_INSTRUCTION:

		/* TODO: support IO bitmaps */

		return 1;

		return nested_vmx_exit_handled_io(vcpu, vmcs12);

	case EXIT_REASON_MSR_READ:

	case EXIT_REASON_MSR_WRITE:

		return nested_vmx_exit_handled_msr(vcpu, vmcs12, exit_reason);