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Subject[PATCH v6 0/4] KVM: nSVM: ondemand nested state allocation
This is the next version of this patch series.

In V5 I adopted Sean Christopherson's suggestion to make .set_efer return
a negative error (-ENOMEM in this case) which in most cases in kvm
propagates to the userspace.

I noticed though that wrmsr emulation code doesn't do this and instead
it injects #GP to the guest on _any_ error.

So I fixed the wrmsr code to behave in a similar way to the rest
of the kvm code.
(#GP only on a positive error value, and forward the negative error to
the userspace)

I had to adjust one wrmsr handler (xen_hvm_config) to stop it from returning
negative values so that new WRMSR emulation behavior doesn't break it.
This patch was only compile tested.

The memory allocation failure was tested by always returning -ENOMEM
from svm_allocate_nested.

The nested allocation itself was tested by countless attempts to run
nested guests, do nested migration on both my AMD and Intel machines.
I wasn't able to break it.

Changes from V5: addressed Sean Christopherson's review feedback.

Best regards,
Maxim Levitsky

Maxim Levitsky (4):
KVM: x86: xen_hvm_config: cleanup return values
KVM: x86: report negative values from wrmsr emulation to userspace
KVM: x86: allow kvm_x86_ops.set_efer to return an error value
KVM: nSVM: implement on demand allocation of the nested state

arch/x86/include/asm/kvm_host.h | 2 +-
arch/x86/kvm/emulate.c | 7 ++--
arch/x86/kvm/svm/nested.c | 42 ++++++++++++++++++++++++
arch/x86/kvm/svm/svm.c | 58 +++++++++++++++++++--------------
arch/x86/kvm/svm/svm.h | 8 ++++-
arch/x86/kvm/vmx/vmx.c | 6 ++--
arch/x86/kvm/x86.c | 37 ++++++++++++---------
7 files changed, 113 insertions(+), 47 deletions(-)


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