[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [V0 PATCH] SVM: set/unset TF flag for single_step
On Wed, 02 Jul 2014 09:38:40 +0100 "Jan Beulich" <JBeulich@xxxxxxxx> wrote: > >>> On 02.07.14 at 05:36, <boris.ostrovsky@xxxxxxxxxx> wrote: > >> --- a/xen/arch/x86/hvm/svm/svm.c > >> +++ b/xen/arch/x86/hvm/svm/svm.c > >> @@ -2350,6 +2350,8 @@ void svm_vmexit_handler(struct cpu_user_regs > >> *regs) > >> case VMEXIT_EXCEPTION_DB: > >> if ( !v->domain->debugger_attached ) > >> goto exit_and_crash; > >> + else > >> + regs->eflags &= ~X86_EFLAGS_TF; > >> domain_pause_for_debugger(); > >> break; > > > > > > I poked around debugger code and it looks to me that > > tools/debugger/gdbsx/xg:_change_TF() manages this flag. _change_TF() only manages TF if XEN_DOMCTL_debug_op fails. Moreover, TF handling is intended for PV. For HVM, xen provides XEN_DOMCTL_debug_op which sets v->arch.hvm_vcpu.single_step. > Indeed it shouldn't be the hypervisor to deal with that (unless it had > a built-in one), but the debugger attached. Correct. But, the hyp provides abi hvm_debug_op (XEN_DOMCTL_DEBUG_OP_SINGLE_STEP_ON) that it needs to honor for svm like it does for vmx. > That said, Mukesh, just as a side note: There's no point for an "else" > after an "if" leading to a "goto". Right. My "doh!". Thanks Mukesh _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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