On 4.04.2022 14:27, Maxim Levitsky wrote:
On Sat, 2022-04-02 at 01:09 +0000, Sean Christopherson wrote:
From: Maciej S. Szmigiero <maciej.szmigiero@xxxxxxxxxx>
Add a KVM self-test that checks whether a nSVM L1 is able to successfully
inject a software interrupt and a soft exception into its L2 guest.
In practice, this tests both the next_rip field consistency and
L1-injected event with intervening L0 VMEXIT during its delivery:
the first nested VMRUN (that's also trying to inject a software interrupt)
will immediately trigger a L0 NPF.
This L0 NPF will have zero in its CPU-returned next_rip field, which if
incorrectly reused by KVM will trigger a #PF when trying to return to
such address 0 from the interrupt handler.
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@xxxxxxxxxx>
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
tools/testing/selftests/kvm/.gitignore | 1 +
tools/testing/selftests/kvm/Makefile | 1 +
.../selftests/kvm/include/x86_64/svm_util.h | 2 +
.../kvm/x86_64/svm_nested_soft_inject_test.c | 147 ++++++++++++++++++
4 files changed, 151 insertions(+)
create mode 100644 tools/testing/selftests/kvm/x86_64/svm_nested_soft_inject_test.c
(..)
diff --git a/tools/testing/selftests/kvm/x86_64/svm_nested_soft_inject_test.c b/tools/testing/selftests/kvm/x86_64/svm_nested_soft_inject_test.c
new file mode 100644
index 000000000000..d39be5d885c1
--- /dev/null
+++ b/tools/testing/selftests/kvm/x86_64/svm_nested_soft_inject_test.c
@@ -0,0 +1,147 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2022 Oracle and/or its affiliates.
+ *
+ * Based on:
+ * svm_int_ctl_test
+ *
+ * Copyright (C) 2021, Red Hat, Inc.
+ *
+ */
+
+#include "test_util.h"
+#include "kvm_util.h"
+#include "processor.h"
+#include "svm_util.h"
+
+#define VCPU_ID 0
+#define INT_NR 0x20
+#define X86_FEATURE_NRIPS BIT(3)
+
+#define vmcall() \
+ __asm__ __volatile__( \
+ "vmmcall\n" \
+ )
+
+#define ud2() \
+ __asm__ __volatile__( \
+ "ud2\n" \
+ )
+
+#define hlt() \
+ __asm__ __volatile__( \
+ "hlt\n" \
+ )
Minor nitpick: I guess it would be nice to put these in some common header file.
Will move these to include/x86_64/processor.h (that's probably the most
matching header file).
+
+static void l1_guest_code(struct svm_test_data *svm)
+{
+ #define L2_GUEST_STACK_SIZE 64
+ unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE];
+ struct vmcb *vmcb = svm->vmcb;
+
+ /* Prepare for L2 execution. */
+ generic_svm_setup(svm, l2_guest_code,
+ &l2_guest_stack[L2_GUEST_STACK_SIZE]);
+
+ vmcb->control.intercept_exceptions |= BIT(PF_VECTOR) | BIT(UD_VECTOR);
+ vmcb->control.intercept |= BIT(INTERCEPT_HLT);
+
+ vmcb->control.event_inj = INT_NR | SVM_EVTINJ_VALID | SVM_EVTINJ_TYPE_SOFT;
+ /* The return address pushed on stack */
+ vmcb->control.next_rip = vmcb->save.rip;
I'll would be putting even something more spicy here just to see that KVM preserves this field
like say put two ud2 in the start of guest code, and here have
vmcb->control.next_rip = vmcb->save.rip + 4; // skip over two ud2 instructions.
That way KVM won't be able to skip over a single instruction to get correct next_rip
Good point, will add these two additional ud2s at the start of L2 guest code.
Other that nitpicks:
Reviewed-by: Maxim levitsky <mlevitsk@xxxxxxxxxx>
Best regards,
Maxim Levitsky
Thanks,
Maciej
