From: Jan Kiszka <jan.kiszka@xxxxxxxxxxx>
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>
---
If someone tells me how to figure out the effective I/O access range
with rep ins/outs in all possible CPU modes in three lines, I'll
complete this patch. For now I had no use and was too lazy.
arch/x86/kvm/vmx.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++-
1 files changed, 52 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index fe9a9cf..056bd95 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -5913,6 +5913,57 @@ 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(get_vmcs12(vcpu), CPU_BASED_UNCOND_IO_EXITING))
+ return 1;
+
+ if (!nested_cpu_has(get_vmcs12(vcpu), 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;
+
+ 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 / 8;
+
+ if (last_bitmap != bitmap)
+ kvm_read_guest(vcpu->kvm, bitmap, &b, 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
@@ -6102,8 +6153,7 @@ 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);
--
1.7.3.4
--
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