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: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 6667042..b4ce43c 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -5908,6 +5908,52 @@
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 @@
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);