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| author | Vitaly Kuznetsov <vkuznets@redhat.com> | 2019-08-13 15:53:33 +0200 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2019-08-22 10:09:21 +0200 |
| commit | c4762fdab55cb1ad715c427f875a549ef257dbb9 (patch) | |
| tree | 5a9591a6e3884e50478af08b72f036b96216d827 /lib/test_overflow.c | |
| parent | 02d4160fbd765110e836c84c30c7babb5af84a44 (diff) | |
| download | lwn-c4762fdab55cb1ad715c427f875a549ef257dbb9.tar.gz lwn-c4762fdab55cb1ad715c427f875a549ef257dbb9.zip | |
x86: KVM: svm: remove hardcoded instruction length from intercepts
Various intercepts hard-code the respective instruction lengths to optimize
skip_emulated_instruction(): when next_rip is pre-set we skip
kvm_emulate_instruction(vcpu, EMULTYPE_SKIP). The optimization is, however,
incorrect: different (redundant) prefixes could be used to enlarge the
instruction. We can't really avoid decoding.
svm->next_rip is not used when CPU supports 'nrips' (X86_FEATURE_NRIPS)
feature: next RIP is provided in VMCB. The feature is not really new
(Opteron G3s had it already) and the change should have zero affect.
Remove manual svm->next_rip setting with hard-coded instruction lengths.
The only case where we now use svm->next_rip is EXIT_IOIO: the instruction
length is provided to us by hardware.
Hardcoded RIP advancement remains in vmrun_interception(), this is going to
be taken care of separately.
Reported-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'lib/test_overflow.c')
0 files changed, 0 insertions, 0 deletions