[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v1] xen: get rid of paravirt op adjust_exception_frame
> On Jul 26, 2017, at 11:50 AM, Juergen Gross <jgross@xxxxxxxx> wrote: > >> On 26/07/17 15:48, Andy Lutomirski wrote: >>> On Mon, Jul 24, 2017 at 7:28 AM, Juergen Gross <jgross@xxxxxxxx> wrote: >>> When running as Xen pv-guest the exception frame on the stack contains >>> %r11 and %rcx additional to the other data pushed by the processor. >>> >>> Instead of having a paravirt op being called for each exception type >>> prepend the Xen specific code to each exception entry. When running as >>> Xen pv-guest just use the exception entry with prepended instructions, >>> otherwise use the entry without the Xen specific code. >> >> I think this is a nice cleanup, but I'm wondering if it would be even >> nicer if the Xen part was kept out-of-line. That is, could Xen have >> little stubs like: >> >> xen_alignment_check: >> pop %rcx >> pop %r11 >> jmp alignment_check >> >> rather than using the macros in entry_64.S that you have? Then you >> could adjust set_trap_gate instead of pack_gate and maybe even do >> something like: >> >> #define set_trap_gate(..., name, ...) set_native_or_xen_trap_gate(..., >> name, xen_##name, ...) > > I think I'll have something like: > > #define pv_trap_entry(name) (xen_pv_domain() ? xen_ ## name : name) > > and use it like: > > set_intr_gate(X86_TRAP_AC, pv_trap_entry(alignment_check)); > > This will avoid having to define macros for all variants of > set_intr_gate(), e.g. set_intr_gate_ist(), set_system_intr_gate(). > > Do you have any objections? > Sounds good to me. FWIW, I have no real objection to putting the Xen entry right before the native entry and falling through. I don't love the ip -= 3 bit, though, and I think that the PV_ENTRY macro is too magical. This might be okay, though: XEN_PV_ENTRY_FALLTHROUGH(foo) ENTRY(foo) code here > > Juergen _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx https://lists.xen.org/xen-devel
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