On Thu, 6 Aug 2020 15:08:35 +1000 David Gibson <da...@gibson.dropbear.id.au> wrote:
> On Wed, Aug 05, 2020 at 07:35:37PM +0200, Greg Kurz wrote: > > Calls to the KVM XIVE device are guarded by kvm_irqchip_in_kernel(). This > > ensures that QEMU won't try to use the device if KVM is disabled or if > > an in-kernel irqchip isn't required. > > > > When using ic-mode=dual with the pseries machine, we have two possible > > interrupt controllers: XIVE and XICS. The kvm_irqchip_in_kernel() helper > > will return true as soon as any of the KVM device is created. It might > > lure QEMU to think that the other one is also around, while it is not. > > This is exactly what happens with ic-mode=dual at machine init when > > claiming IRQ numbers, which must be done on all possible IRQ backends, > > eg. RTAS event sources or the PHB0 LSI table : only the KVM XICS device > > is active but we end up calling kvmppc_xive_source_reset_one() anyway, > > which fails. This doesn't cause any trouble because of another bug : > > kvmppc_xive_source_reset_one() lacks an error_setg() and callers don't > > see the failure. > > > > Most of the other kvmppc_xive_* functions have similar xive->fd > > checks to filter out the case when KVM XIVE isn't active. It > > might look safer to have idempotent functions but it doesn't > > really help to understand what's going on when debugging. > > > > Since we already have all the kvm_irqchip_in_kernel() in place, > > also have the callers to check xive->fd as well before calling > > KVM XIVE specific code. Introduce helpers to access the underlying > > fd for various XIVE types and call them with a kvm_irqchip_in_kernel() > > guard : this allows the compiler to optimize the kvmppc_xive_* calls > > out if CONFIG_KVM isn't defined, thus avoiding the need for stubs. > > > > Signed-off-by: Greg Kurz <gr...@kaod.org> > > --- > > hw/intc/spapr_xive.c | 39 +++++++++++++++++++++++++-------------- > > hw/intc/spapr_xive_kvm.c | 15 +++++++++++++++ > > hw/intc/xive.c | 30 +++++++++++++++++++++++------- > > include/hw/ppc/spapr_xive.h | 1 + > > include/hw/ppc/xive.h | 2 ++ > > 5 files changed, 66 insertions(+), 21 deletions(-) > > > > diff --git a/hw/intc/spapr_xive.c b/hw/intc/spapr_xive.c > > index 89c8cd96670b..98e6489fb16d 100644 > > --- a/hw/intc/spapr_xive.c > > +++ b/hw/intc/spapr_xive.c > > @@ -148,12 +148,19 @@ static void spapr_xive_end_pic_print_info(SpaprXive > > *xive, XiveEND *end, > > xive_end_queue_pic_print_info(end, 6, mon); > > } > > > > +/* > > + * kvm_irqchip_in_kernel() will cause the compiler to turn this > > + * info a nop if CONFIG_KVM isn't defined. > > + */ > > +#define kvmppc_xive_in_kernel(xive) \ > > + (kvm_irqchip_in_kernel() && kvmppc_xive_kernel_irqchip(xive)) > > This all seems like a good idea, my only concern is that the semantic > difference between kvmppc_xive_in_kernel() and > kvmppc_xive_kernel_irqchip() is pretty subtle and non-obvious (and > likewise for the tctx and xsrc variations). > Yeah, kvmppc_xive_in_kernel() and friends are essentially versions that also work when CONFIG_KVM is not set (needed to build qemu-system-ppc64 for non-POWER hosts). > We're right in the XIVE implementation, so I suggest you eliminate the > kvmppc_xive_kernel_irqchip() etc. wrappers and just open code a check > on the fd in kvmppc_xive_in_kernel() etc. > This is true for the kvmppc_xive_in_kernel() variant that takes a SpaprXive * arg. Things are different for the tctx and xsrc variants, because xive.c is platform agnostic (shared between spapr and powernv). Exposing the SpaprXive type to xive.c would look like a layering violation to me. Maybe introducing abstract class methods at the base XIVE level (eg. XivePresenterClass) and implement them in platform-specific code would make things clearer ? > > + > > void spapr_xive_pic_print_info(SpaprXive *xive, Monitor *mon) > > { > > XiveSource *xsrc = &xive->source; > > int i; > > > > - if (kvm_irqchip_in_kernel()) { > > + if (kvmppc_xive_in_kernel(xive)) { > > Error *local_err = NULL; > > > > kvmppc_xive_synchronize_state(xive, &local_err); > > @@ -507,8 +514,10 @@ static const VMStateDescription vmstate_spapr_xive_eas > > = { > > > > static int vmstate_spapr_xive_pre_save(void *opaque) > > { > > - if (kvm_irqchip_in_kernel()) { > > - return kvmppc_xive_pre_save(SPAPR_XIVE(opaque)); > > + SpaprXive *xive = SPAPR_XIVE(opaque); > > + > > + if (kvmppc_xive_in_kernel(xive)) { > > + return kvmppc_xive_pre_save(xive); > > } > > > > return 0; > > @@ -520,8 +529,10 @@ static int vmstate_spapr_xive_pre_save(void *opaque) > > */ > > static int spapr_xive_post_load(SpaprInterruptController *intc, int > > version_id) > > { > > - if (kvm_irqchip_in_kernel()) { > > - return kvmppc_xive_post_load(SPAPR_XIVE(intc), version_id); > > + SpaprXive *xive = SPAPR_XIVE(intc); > > + > > + if (kvmppc_xive_in_kernel(xive)) { > > + return kvmppc_xive_post_load(xive, version_id); > > } > > > > return 0; > > @@ -564,7 +575,7 @@ static int > > spapr_xive_claim_irq(SpaprInterruptController *intc, int lisn, > > xive_source_irq_set_lsi(xsrc, lisn); > > } > > > > - if (kvm_irqchip_in_kernel()) { > > + if (kvmppc_xive_in_kernel(xive)) { > > return kvmppc_xive_source_reset_one(xsrc, lisn, errp); > > } > > > > @@ -641,7 +652,7 @@ static void spapr_xive_set_irq(SpaprInterruptController > > *intc, int irq, int val) > > { > > SpaprXive *xive = SPAPR_XIVE(intc); > > > > - if (kvm_irqchip_in_kernel()) { > > + if (kvmppc_xive_in_kernel(xive)) { > > kvmppc_xive_source_set_irq(&xive->source, irq, val); > > } else { > > xive_source_set_irq(&xive->source, irq, val); > > @@ -749,7 +760,7 @@ static void > > spapr_xive_deactivate(SpaprInterruptController *intc) > > > > spapr_xive_mmio_set_enabled(xive, false); > > > > - if (kvm_irqchip_in_kernel()) { > > + if (kvmppc_xive_in_kernel(xive)) { > > kvmppc_xive_disconnect(intc); > > } > > } > > @@ -1058,7 +1069,7 @@ static target_ulong > > h_int_set_source_config(PowerPCCPU *cpu, > > new_eas.w = xive_set_field64(EAS_END_DATA, new_eas.w, eisn); > > } > > > > - if (kvm_irqchip_in_kernel()) { > > + if (kvmppc_xive_in_kernel(xive)) { > > Error *local_err = NULL; > > > > kvmppc_xive_set_source_config(xive, lisn, &new_eas, &local_err); > > @@ -1379,7 +1390,7 @@ static target_ulong h_int_set_queue_config(PowerPCCPU > > *cpu, > > */ > > > > out: > > - if (kvm_irqchip_in_kernel()) { > > + if (kvmppc_xive_in_kernel(xive)) { > > Error *local_err = NULL; > > > > kvmppc_xive_set_queue_config(xive, end_blk, end_idx, &end, > > &local_err); > > @@ -1480,7 +1491,7 @@ static target_ulong h_int_get_queue_config(PowerPCCPU > > *cpu, > > args[2] = 0; > > } > > > > - if (kvm_irqchip_in_kernel()) { > > + if (kvmppc_xive_in_kernel(xive)) { > > Error *local_err = NULL; > > > > kvmppc_xive_get_queue_config(xive, end_blk, end_idx, end, > > &local_err); > > @@ -1642,7 +1653,7 @@ static target_ulong h_int_esb(PowerPCCPU *cpu, > > return H_P3; > > } > > > > - if (kvm_irqchip_in_kernel()) { > > + if (kvmppc_xive_in_kernel(xive)) { > > args[0] = kvmppc_xive_esb_rw(xsrc, lisn, offset, data, > > flags & SPAPR_XIVE_ESB_STORE); > > } else { > > @@ -1717,7 +1728,7 @@ static target_ulong h_int_sync(PowerPCCPU *cpu, > > * under KVM > > */ > > > > - if (kvm_irqchip_in_kernel()) { > > + if (kvmppc_xive_in_kernel(xive)) { > > Error *local_err = NULL; > > > > kvmppc_xive_sync_source(xive, lisn, &local_err); > > @@ -1761,7 +1772,7 @@ static target_ulong h_int_reset(PowerPCCPU *cpu, > > > > device_legacy_reset(DEVICE(xive)); > > > > - if (kvm_irqchip_in_kernel()) { > > + if (kvmppc_xive_in_kernel(xive)) { > > Error *local_err = NULL; > > > > kvmppc_xive_reset(xive, &local_err); > > diff --git a/hw/intc/spapr_xive_kvm.c b/hw/intc/spapr_xive_kvm.c > > index 893a1ee77e70..a9657e2b0cda 100644 > > --- a/hw/intc/spapr_xive_kvm.c > > +++ b/hw/intc/spapr_xive_kvm.c > > @@ -889,3 +889,18 @@ void kvmppc_xive_disconnect(SpaprInterruptController > > *intc) > > xive->change = NULL; > > } > > } > > + > > +bool kvmppc_xive_kernel_irqchip(SpaprXive *xive) > > +{ > > + return xive->fd != -1; > > +} > > + > > +bool kvmppc_xive_kernel_irqchip_tctx(XiveTCTX *tctx) > > +{ > > + return kvmppc_xive_kernel_irqchip(SPAPR_XIVE(tctx->xptr)); > > +} > > + > > +bool kvmppc_xive_kernel_irqchip_xsrc(XiveSource *xsrc) > > +{ > > + return kvmppc_xive_kernel_irqchip(SPAPR_XIVE(xsrc->xive)); > > +} > > diff --git a/hw/intc/xive.c b/hw/intc/xive.c > > index 9b55e0356c62..2e1af4530dc5 100644 > > --- a/hw/intc/xive.c > > +++ b/hw/intc/xive.c > > @@ -592,6 +592,13 @@ static const char * const xive_tctx_ring_names[] = { > > "USER", "OS", "POOL", "PHYS", > > }; > > > > +/* > > + * kvm_irqchip_in_kernel() will cause the compiler to turn this > > + * info a nop if CONFIG_KVM isn't defined. > > + */ > > +#define kvmppc_xive_in_kernel_tctx(tctx) \ > > + (kvm_irqchip_in_kernel() && kvmppc_xive_kernel_irqchip_tctx(tctx)) > > + > > void xive_tctx_pic_print_info(XiveTCTX *tctx, Monitor *mon) > > { > > int cpu_index; > > @@ -606,7 +613,7 @@ void xive_tctx_pic_print_info(XiveTCTX *tctx, Monitor > > *mon) > > > > cpu_index = tctx->cs ? tctx->cs->cpu_index : -1; > > > > - if (kvm_irqchip_in_kernel()) { > > + if (kvmppc_xive_in_kernel_tctx(tctx)) { > > Error *local_err = NULL; > > > > kvmppc_xive_cpu_synchronize_state(tctx, &local_err); > > @@ -671,7 +678,7 @@ static void xive_tctx_realize(DeviceState *dev, Error > > **errp) > > } > > > > /* Connect the presenter to the VCPU (required for CPU hotplug) */ > > - if (kvm_irqchip_in_kernel()) { > > + if (kvmppc_xive_in_kernel_tctx(tctx)) { > > kvmppc_xive_cpu_connect(tctx, &local_err); > > if (local_err) { > > error_propagate(errp, local_err); > > @@ -682,10 +689,11 @@ static void xive_tctx_realize(DeviceState *dev, Error > > **errp) > > > > static int vmstate_xive_tctx_pre_save(void *opaque) > > { > > + XiveTCTX *tctx = XIVE_TCTX(opaque); > > Error *local_err = NULL; > > > > - if (kvm_irqchip_in_kernel()) { > > - kvmppc_xive_cpu_get_state(XIVE_TCTX(opaque), &local_err); > > + if (kvmppc_xive_in_kernel_tctx(tctx)) { > > + kvmppc_xive_cpu_get_state(tctx, &local_err); > > if (local_err) { > > error_report_err(local_err); > > return -1; > > @@ -697,14 +705,15 @@ static int vmstate_xive_tctx_pre_save(void *opaque) > > > > static int vmstate_xive_tctx_post_load(void *opaque, int version_id) > > { > > + XiveTCTX *tctx = XIVE_TCTX(opaque); > > Error *local_err = NULL; > > > > - if (kvm_irqchip_in_kernel()) { > > + if (kvmppc_xive_in_kernel_tctx(tctx)) { > > /* > > * Required for hotplugged CPU, for which the state comes > > * after all states of the machine. > > */ > > - kvmppc_xive_cpu_set_state(XIVE_TCTX(opaque), &local_err); > > + kvmppc_xive_cpu_set_state(tctx, &local_err); > > if (local_err) { > > error_report_err(local_err); > > return -1; > > @@ -1125,6 +1134,13 @@ static void xive_source_reset(void *dev) > > memset(xsrc->status, XIVE_ESB_OFF, xsrc->nr_irqs); > > } > > > > +/* > > + * kvm_irqchip_in_kernel() will cause the compiler to turn this > > + * info a nop if CONFIG_KVM isn't defined. > > + */ > > +#define kvmppc_xive_in_kernel_xsrc(xsrc) \ > > + (kvm_irqchip_in_kernel() && kvmppc_xive_kernel_irqchip_xsrc(xsrc)) > > + > > static void xive_source_realize(DeviceState *dev, Error **errp) > > { > > XiveSource *xsrc = XIVE_SOURCE(dev); > > @@ -1147,7 +1163,7 @@ static void xive_source_realize(DeviceState *dev, > > Error **errp) > > xsrc->status = g_malloc0(xsrc->nr_irqs); > > xsrc->lsi_map = bitmap_new(xsrc->nr_irqs); > > > > - if (!kvm_irqchip_in_kernel()) { > > + if (!kvmppc_xive_in_kernel_xsrc(xsrc)) { > > memory_region_init_io(&xsrc->esb_mmio, OBJECT(xsrc), > > &xive_source_esb_ops, xsrc, "xive.esb", > > (1ull << xsrc->esb_shift) * xsrc->nr_irqs); > > diff --git a/include/hw/ppc/spapr_xive.h b/include/hw/ppc/spapr_xive.h > > index 93d09d68deb7..9fd00378ac1f 100644 > > --- a/include/hw/ppc/spapr_xive.h > > +++ b/include/hw/ppc/spapr_xive.h > > @@ -94,5 +94,6 @@ void kvmppc_xive_get_queue_config(SpaprXive *xive, > > uint8_t end_blk, > > void kvmppc_xive_synchronize_state(SpaprXive *xive, Error **errp); > > int kvmppc_xive_pre_save(SpaprXive *xive); > > int kvmppc_xive_post_load(SpaprXive *xive, int version_id); > > +bool kvmppc_xive_kernel_irqchip(SpaprXive *xive); > > > > #endif /* PPC_SPAPR_XIVE_H */ > > diff --git a/include/hw/ppc/xive.h b/include/hw/ppc/xive.h > > index 705cf48176fc..ea66e9ea9c7b 100644 > > --- a/include/hw/ppc/xive.h > > +++ b/include/hw/ppc/xive.h > > @@ -484,5 +484,7 @@ void kvmppc_xive_cpu_connect(XiveTCTX *tctx, Error > > **errp); > > void kvmppc_xive_cpu_synchronize_state(XiveTCTX *tctx, Error **errp); > > void kvmppc_xive_cpu_get_state(XiveTCTX *tctx, Error **errp); > > void kvmppc_xive_cpu_set_state(XiveTCTX *tctx, Error **errp); > > +bool kvmppc_xive_kernel_irqchip_tctx(XiveTCTX *tctx); > > +bool kvmppc_xive_kernel_irqchip_xsrc(XiveSource *xsrc); > > > > #endif /* PPC_XIVE_H */ > > > > >
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