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 <[email protected]> > --- > > 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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