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Subject[PATCH 0/5] nSVM: L1 -> L2 event injection fixes and a self-test
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From: "Maciej S. Szmigiero" <maciej.szmigiero@oracle.com>

There are some issues with respect to nSVM L1 -> L2 event injection.

First, the next_rip field of a VMCB is *not* an output-only field for a VMRUN.
This field value (instead of the saved guest RIP) in used by the CPU for
the return address pushed on stack when injecting a software interrupt or
INT3 or INTO exception (this was confirmed by AMD).

On a VMRUN that does event injection it has similar function as VMX's
VM_ENTRY_INSTRUCTION_LEN field, although, in contrast to VMX, it holds an
absolute RIP value, not a relative increment.

However, KVM seems to treat this field as a unidirectional hint from the CPU
to the hypervisor - there seems to be no specific effort to maintain this
field consistency for such VMRUN.

This is mostly visible with running a nested guest, with L1 trying to inject
an event into its L2.
In this case, we need to make sure the next_rip field gets synced from
vmcb12 to vmcb02.

Another issue is that pending L1 -> L2 events are forgotten if there is an
intervening L0 VMEXIT during their delivery.
We need to make sure they are remembered (including their desired next_rip
field value) until they are either re-injected into L2 successfully or
returned back to L1 in the EXITINTINFO field upon a nested VMEXIT.

A new KVM self-test that checks for the nSVM issues described above is
included in this patch series.

These issues are SVM-specific - all the use cases described above already
work correctly with VMX.

This patch set was tested with both Linux and Windows nested guests.

KVM: nSVM: Sync next_rip field from vmcb12 to vmcb02
KVM: SVM: Downgrade BUG_ON() to WARN_ON() in svm_inject_irq()
KVM: nSVM: Don't forget about L1-injected events
KVM: nSVM: Restore next_rip when doing L1 -> L2 event re-injection
KVM: selftests: nSVM: Add svm_nested_soft_inject_test

arch/x86/kvm/svm/nested.c | 69 +++++++-
arch/x86/kvm/svm/svm.c | 60 ++++++-
arch/x86/kvm/svm/svm.h | 48 ++++++
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 ++++++++++++++++++
7 files changed, 324 insertions(+), 4 deletions(-)
create mode 100644 tools/testing/selftests/kvm/x86_64/svm_nested_soft_inject_test.c

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