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KVM: nVMX: Improve I/O exit handling

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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>
This commit is contained in:
Jan Kiszka 2013-02-18 11:21:16 +01:00 committed by Marcelo Tosatti
parent 6b73a96065
commit 908a7bdd6a
1 changed files with 47 additions and 2 deletions
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49
arch/x86/kvm/vmx.c
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@ -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);