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| author | Paolo Bonzini <pbonzini@redhat.com> | 2014-02-21 10:32:27 +0100 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2014-03-11 10:46:04 +0100 |
| commit | facb0139698923dc7b7d15cafbb319219969f4fd (patch) | |
| tree | d2f4e83b00ecfc8d744c8f8af5510bca5a8185cc /Documentation/virtual/kvm/api.txt | |
| parent | KVM: svm: set/clear all DR intercepts in one swoop (diff) | |
| download | linux-facb0139698923dc7b7d15cafbb319219969f4fd.tar.xz linux-facb0139698923dc7b7d15cafbb319219969f4fd.zip | |
KVM: svm: Allow the guest to run with dirty debug registers
When not running in guest-debug mode (i.e. the guest controls the debug
registers, having to take an exit for each DR access is a waste of time.
If the guest gets into a state where each context switch causes DR to be
saved and restored, this can take away as much as 40% of the execution
time from the guest.
If the guest is running with vcpu->arch.db == vcpu->arch.eff_db, we
can let it write freely to the debug registers and reload them on the
next exit. We still need to exit on the first access, so that the
KVM_DEBUGREG_WONT_EXIT flag is set in switch_db_regs; after that, further
accesses to the debug registers will not cause a vmexit.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'Documentation/virtual/kvm/api.txt')
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