[PATCH 4.19 72/97] KVM: nVMX: Check IO instruction VM-exit conditions

Greg Kroah-Hartman
2020-02-27T14:29:56Z

From: Oliver Upton <oupton@google.com>

commit 35a571346a94fb93b5b3b6a599675ef3384bc75c upstream.

Consult the 'unconditional IO exiting' and 'use IO bitmaps' VM-execution
controls when checking instruction interception. If the 'use IO bitmaps'
VM-execution control is 1, check the instruction access against the IO
bitmaps to determine if the instruction causes a VM-exit.

Signed-off-by: Oliver Upton <oupton@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/x86/kvm/vmx.c | 59 ++++++++++++++++++++++++++++++++++++++++++++++-------
1 file changed, 52 insertions(+), 7 deletions(-)

--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -5731,7 +5731,7 @@ static bool nested_vmx_exit_handled_io(s
struct vmcs12 *vmcs12)
{
unsigned long exit_qualification;
- unsigned int port;
+ unsigned short port;
int size;

if (!nested_cpu_has(vmcs12, CPU_BASED_USE_IO_BITMAPS))
@@ -13689,6 +13689,39 @@ static void nested_vmx_entry_failure(str
to_vmx(vcpu)->nested.sync_shadow_vmcs = true;
}

+static int vmx_check_intercept_io(struct kvm_vcpu *vcpu,
+ struct x86_instruction_info *info)
+{
+ struct vmcs12 *vmcs12 = get_vmcs12(vcpu);
+ unsigned short port;
+ bool intercept;
+ int size;
+
+ if (info->intercept == x86_intercept_in ||
+ info->intercept == x86_intercept_ins) {
+ port = info->src_val;
+ size = info->dst_bytes;
+ } else {
+ port = info->dst_val;
+ size = info->src_bytes;
+ }
+
+ /*
+ * If the 'use IO bitmaps' VM-execution control is 0, IO instruction
+ * VM-exits depend on the 'unconditional IO exiting' VM-execution
+ * control.
+ *
+ * Otherwise, IO instruction VM-exits are controlled by the IO bitmaps.
+ */
+ if (!nested_cpu_has(vmcs12, CPU_BASED_USE_IO_BITMAPS))
+ intercept = nested_cpu_has(vmcs12,
+ CPU_BASED_UNCOND_IO_EXITING);
+ else
+ intercept = nested_vmx_check_io_bitmaps(vcpu, port, size);
+
+ return intercept ? X86EMUL_UNHANDLEABLE : X86EMUL_CONTINUE;
+}
+
static int vmx_check_intercept(struct kvm_vcpu *vcpu,
struct x86_instruction_info *info,
enum x86_intercept_stage stage)
@@ -13696,18 +13729,30 @@ static int vmx_check_intercept(struct kv
struct vmcs12 *vmcs12 = get_vmcs12(vcpu);
struct x86_emulate_ctxt *ctxt = &vcpu->arch.emulate_ctxt;

+ switch (info->intercept) {
/*
* RDPID causes #UD if disabled through secondary execution controls.
* Because it is marked as EmulateOnUD, we need to intercept it here.
*/
- if (info->intercept == x86_intercept_rdtscp &&
- !nested_cpu_has2(vmcs12, SECONDARY_EXEC_RDTSCP)) {
- ctxt->exception.vector = UD_VECTOR;
- ctxt->exception.error_code_valid = false;
- return X86EMUL_PROPAGATE_FAULT;
- }
+ case x86_intercept_rdtscp:
+ if (!nested_cpu_has2(vmcs12, SECONDARY_EXEC_RDTSCP)) {
+ ctxt->exception.vector = UD_VECTOR;
+ ctxt->exception.error_code_valid = false;
+ return X86EMUL_PROPAGATE_FAULT;
+ }
+ break;
+
+ case x86_intercept_in:
+ case x86_intercept_ins:
+ case x86_intercept_out:
+ case x86_intercept_outs:
+ return vmx_check_intercept_io(vcpu, info);

/* TODO: check more intercepts... */
+ default:
+ break;
+ }
+
return X86EMUL_UNHANDLEABLE;
}