On Tue, Apr 24, 2018 at 10:11:27AM +0200, Cédric Le Goater wrote: > On 04/24/2018 08:41 AM, David Gibson wrote: > > On Mon, Apr 23, 2018 at 09:31:24AM +0200, Cédric Le Goater wrote: > >> On 04/23/2018 08:44 AM, David Gibson wrote: > >>> On Thu, Apr 19, 2018 at 02:42:58PM +0200, Cédric Le Goater wrote: > >>>> The 'sent' status of the LSI interrupt source is modeled with the 'P' > >>>> bit of the ESB and the assertion status of the source is maintained in > >>>> an array under the main sPAPRXive object. The type of the source is > >>>> stored in the same array for practical reasons. > >>>> > >>>> Signed-off-by: Cédric Le Goater <[email protected]> > >>>> --- > >>>> hw/intc/xive.c | 54 > >>>> +++++++++++++++++++++++++++++++++++++++++++++++---- > >>>> include/hw/ppc/xive.h | 16 +++++++++++++++ > >>>> 2 files changed, 66 insertions(+), 4 deletions(-) > >>>> > >>>> diff --git a/hw/intc/xive.c b/hw/intc/xive.c > >>>> index c70578759d02..060976077dd7 100644 > >>>> --- a/hw/intc/xive.c > >>>> +++ b/hw/intc/xive.c > >>>> @@ -104,6 +104,21 @@ static void xive_source_notify(XiveSource *xsrc, > >>>> int srcno) > >>>> > >>>> } > >>>> > >>>> +/* > >>>> + * LSI interrupt sources use the P bit and a custom assertion flag > >>>> + */ > >>>> +static bool xive_source_lsi_trigger(XiveSource *xsrc, uint32_t srcno) > >>>> +{ > >>>> + uint8_t old_pq = xive_source_pq_get(xsrc, srcno); > >>>> + > >>>> + if (old_pq == XIVE_ESB_RESET && > >>>> + xsrc->status[srcno] & XIVE_STATUS_ASSERTED) { > >>>> + xive_source_pq_set(xsrc, srcno, XIVE_ESB_PENDING); > >>>> + return true; > >>>> + } > >>>> + return false; > >>>> +} > >>>> + > >>>> /* In a two pages ESB MMIO setting, even page is the trigger page, odd > >>>> * page is for management */ > >>>> static inline bool xive_source_is_trigger_page(hwaddr addr) > >>>> @@ -133,6 +148,13 @@ static uint64_t xive_source_esb_read(void *opaque, > >>>> hwaddr addr, unsigned size) > >>>> */ > >>>> ret = xive_source_pq_eoi(xsrc, srcno); > >>>> > >>>> + /* If the LSI source is still asserted, forward a new source > >>>> + * event notification */ > >>>> + if (xive_source_irq_is_lsi(xsrc, srcno)) { > >>>> + if (xive_source_lsi_trigger(xsrc, srcno)) { > >>>> + xive_source_notify(xsrc, srcno); > >>>> + } > >>>> + } > >>>> break; > >>>> > >>>> case XIVE_ESB_GET: > >>>> @@ -183,6 +205,14 @@ static void xive_source_esb_write(void *opaque, > >>>> hwaddr addr, > >>>> * notification > >>>> */ > >>>> notify = xive_source_pq_eoi(xsrc, srcno); > >>>> + > >>>> + /* LSI sources do not set the Q bit but they can still be > >>>> + * asserted, in which case we should forward a new source > >>>> + * event notification > >>>> + */ > >>>> + if (xive_source_irq_is_lsi(xsrc, srcno)) { > >>>> + notify = xive_source_lsi_trigger(xsrc, srcno); > >>>> + } > >> > >> FYI, I have moved that common test under xive_source_pq_eoi() > > > > Ok. > > > >>>> break; > >>>> > >>>> default: > >>>> @@ -216,8 +246,17 @@ static void xive_source_set_irq(void *opaque, int > >>>> srcno, int val) > >>>> XiveSource *xsrc = XIVE_SOURCE(opaque); > >>>> bool notify = false; > >>>> > >>>> - if (val) { > >>>> - notify = xive_source_pq_trigger(xsrc, srcno); > >>>> + if (xive_source_irq_is_lsi(xsrc, srcno)) { > >>>> + if (val) { > >>>> + xsrc->status[srcno] |= XIVE_STATUS_ASSERTED; > >>>> + } else { > >>>> + xsrc->status[srcno] &= ~XIVE_STATUS_ASSERTED; > >>>> + } > >>>> + notify = xive_source_lsi_trigger(xsrc, srcno); > >>>> + } else { > >>>> + if (val) { > >>>> + notify = xive_source_pq_trigger(xsrc, srcno); > >>>> + } > >>>> } > >>>> > >>>> /* Forward the source event notification for routing */ > >>>> @@ -234,13 +273,13 @@ void xive_source_pic_print_info(XiveSource *xsrc, > >>>> Monitor *mon) > >>>> xsrc->offset, xsrc->offset + xsrc->nr_irqs - 1); > >>>> for (i = 0; i < xsrc->nr_irqs; i++) { > >>>> uint8_t pq = xive_source_pq_get(xsrc, i); > >>>> - uint32_t lisn = i + xsrc->offset; > >>>> > >>>> if (pq == XIVE_ESB_OFF) { > >>>> continue; > >>>> } > >>>> > >>>> - monitor_printf(mon, " %4x %c%c\n", lisn, > >>>> + monitor_printf(mon, " %4x %s %c%c\n", i + xsrc->offset, > >>>> + xive_source_irq_is_lsi(xsrc, i) ? "LSI" : "MSI", > >>>> pq & XIVE_ESB_VAL_P ? 'P' : '-', > >>>> pq & XIVE_ESB_VAL_Q ? 'Q' : '-'); > >>>> } > >>>> @@ -249,6 +288,12 @@ void xive_source_pic_print_info(XiveSource *xsrc, > >>>> Monitor *mon) > >>>> static void xive_source_reset(DeviceState *dev) > >>>> { > >>>> XiveSource *xsrc = XIVE_SOURCE(dev); > >>>> + int i; > >>>> + > >>>> + /* Keep the IRQ type */ > >>>> + for (i = 0; i < xsrc->nr_irqs; i++) { > >>>> + xsrc->status[i] &= ~XIVE_STATUS_ASSERTED; > >>>> + } > >>>> > >>>> /* SBEs are initialized to 0b01 which corresponds to "ints off" */ > >>>> memset(xsrc->sbe, 0x55, xsrc->sbe_size); > >>>> @@ -273,6 +318,7 @@ static void xive_source_realize(DeviceState *dev, > >>>> Error **errp) > >>>> > >>>> xsrc->qirqs = qemu_allocate_irqs(xive_source_set_irq, xsrc, > >>>> xsrc->nr_irqs); > >>>> + xsrc->status = g_malloc0(xsrc->nr_irqs); > >>>> > >>>> /* Allocate the SBEs (State Bit Entry). 2 bits, so 4 entries per > >>>> byte */ > >>>> xsrc->sbe_size = DIV_ROUND_UP(xsrc->nr_irqs, 4); > >>>> diff --git a/include/hw/ppc/xive.h b/include/hw/ppc/xive.h > >>>> index d92a50519edf..0b76dd278d9b 100644 > >>>> --- a/include/hw/ppc/xive.h > >>>> +++ b/include/hw/ppc/xive.h > >>>> @@ -33,6 +33,9 @@ typedef struct XiveSource { > >>>> uint32_t nr_irqs; > >>>> uint32_t offset; > >>>> qemu_irq *qirqs; > >>>> +#define XIVE_STATUS_LSI 0x1 > >>>> +#define XIVE_STATUS_ASSERTED 0x2 > >>>> + uint8_t *status; > >>> > >>> I don't love the idea of mixing configuration information (STATUS_LSI) > >>> with runtime state information (ASSERTED) in the same field. Any > >>> reason not to have these as parallel bitmaps. > >> > >> none. I can change that. > > > > Ok. > > > >>> Come to that.. is there a compelling reason to allow any individual > >>> irq to be marked LSI or MSI, rather than using separate XiveSource > >>> objects for MSIs and LSIs? > >> > >> yes. I would have preferred two distinct interrupt source objects but > >> this is to be compatible with XICS, which uses only one. If we want > >> to be able to change interrupt mode, the IRQ number space should be > >> organized in the exact same way. Or we should change XICS also. > >> > >> Also, the change (a bitmap) is really small. > > > > Hrm, but since XIVE supports thousands of irqs, it could be quite a > > large bitmap. > > Yes. The change is small, not the bitmap. > > > It's not impossible - in fact, not really even that hard - to change > > the existing irq layout on xics. It does need a new machine type > > variant, of course. > > I did some work on that topic a while ago : > > https://patchwork.ozlabs.org/cover/836782/ > > But we stopped exploring the idea. May be it was not the good approach. > The PHBs LSIs would benefit from such a split though.
So, no, I don't think that was a good approach, but that doesn't mean
other ways of rearranging the irq numbers aren't ok. The thing here
is that we don't want to think of an "irq allocator" - there are some
bits like that in there already, but they were always a mistake.
We have lots of irq space (both XICS and XIVE) so instead we should
come up with a static mapping of irqs to devices.
> >>>> /* PQ bits */
> >>>> uint8_t *sbe;
> >>>
> >>> .. and come to that is there a reason to keep the ASSERTED bit in a
> >>> separate array from sbe? AFAICT the actual 2-bit-per-irq layout is
> >>> never exposed to the guests.
> >>
> >> indeed. we always use the xive_source_pq_get/set() helpers to
> >> manipulate the PQ bits. So we could add an extra bit for the ASSERT
> >> without too much changes. Could also we put the type there or would
> >> you still prefer a bitmap ?
> >
> > I'd prefer the type (config information) be separate from the P, Q,
> > ASSERTED bits (state information).
>
> ok. So I will use the 'uint8_t *status' for P, Q, ASSERT, which leaves
> 5 bits available, but I don't think it is really worth the pain to
> optimize the size.
Sure. I don't really care if it's packed or not.
> The sbe array will disappear and we will have
> a bitmap for the type.
We may or may not keep the type bitmap based on the discussion above,
but in any case this is a good step forward.
>
> Thanks,
>
> C.
>
> >>> Or, even re-use the Q bit for asserted in LSIs (but report it as
> >>> always 0 in the register read/write path).
> >>
> >> I would prefer to add extra status bits. It is easier to debug.
> >>
> >> Thanks,
> >>
> >> C.
> >>
> >>>> @@ -127,4 +130,17 @@ uint8_t xive_source_pq_set(XiveSource *xsrc,
> >>>> uint32_t srcno, uint8_t pq);
> >>>>
> >>>> void xive_source_pic_print_info(XiveSource *xsrc, Monitor *mon);
> >>>>
> >>>> +static inline bool xive_source_irq_is_lsi(XiveSource *xsrc, uint32_t
> >>>> srcno)
> >>>> +{
> >>>> + assert(srcno < xsrc->nr_irqs);
> >>>> + return xsrc->status[srcno] & XIVE_STATUS_LSI;
> >>>> +}
> >>>> +
> >>>> +static inline void xive_source_irq_set(XiveSource *xsrc, uint32_t srcno,
> >>>> + bool lsi)
> >>>> +{
> >>>> + assert(srcno < xsrc->nr_irqs);
> >>>> + xsrc->status[srcno] |= lsi ? XIVE_STATUS_LSI : 0;
> >>>> +}
> >>>> +
> >>>> #endif /* PPC_XIVE_H */
> >>>
> >>
> >
>
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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