Messages in this thread | | | Date | Tue, 3 Nov 2009 21:29:24 +0100 | From | Frederic Weisbecker <> | Subject | Re: [PATCH 4/6] hw-breakpoints: Rewrite the hw-breakpoints layer on top of perf events |
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On Tue, Nov 03, 2009 at 09:22:04PM +0100, Jan Kiszka wrote: > > Thinking about it, this check should cover every cases: > > > > if (vcpu->arch.switch_db_regs || __get_cpu_var(dr7) & DR_GLOBAL_ENABLE_MASK) > > > > If we have __get_cpu_var(dr7) & DR_GLOBAL_ENABLE_MASK, it means there is an > > active breakpoint and then we should restore the current state. > > > > And what about (__get_cpu_var(dr7) & DR_GLOBAL_ENABLE_MASK) only? Would > you be able to live with unsync'ed hardware and software states? > > Jan >
But if the guest has breakpoints activated, the host will inherit them, which is really not something we want, assuming vcpu->arch.switch_db_regs already protects us about that.
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