On 2013-02-14 19:46, Jan Kiszka wrote:
> This prevents trapping L2 I/O exits if L1 has neither unconditional nor
> bitmap-based exiting enabled. Furthermore, it implements basic I/O
> bitmap handling. Repeated string accesses are still reported to L1
> unconditionally for now.
>
> Signed-off-by: Jan Kiszka <jan.kiszka@xxxxxxxxxxx>
> ---
>
> Changes in v3:
> - trap unconditionally if bitmap access fails
>
> arch/x86/kvm/vmx.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++++++-
> 1 files changed, 53 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 6667042..2633199 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -5908,6 +5908,58 @@ 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;
> + bool string, rep;
> + u16 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);
> +
> + string = exit_qualification & 16;
> + rep = exit_qualification & 32;
> +
> + /* TODO: interpret instruction and check range against bitmap */
> + if (string && rep)
> + return 1;
Nonsense, rep ins/outs always works against the same port. We can simply
drop this check and be done with the feature. I'll come up with v4.
Jan
> +
> + 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
> + bitmap = vmcs12->io_bitmap_b;
> + 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 +6149,7 @@ 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);
>
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