Messages in this thread Patch in this message | | | Date | Thu, 19 Mar 2020 10:55:59 +0000 | From | Marc Zyngier <> | Subject | Re: [PATCH v5 16/23] irqchip/gic-v4.1: Eagerly vmap vPEs |
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On 2020-03-17 02:49, Zenghui Yu wrote: > Hi Marc, > > On 2020/3/5 4:33, Marc Zyngier wrote: >> Now that we have HW-accelerated SGIs being delivered to VPEs, it >> becomes required to map the VPEs on all ITSs instead of relying >> on the lazy approach that we would use when using the ITS-list >> mechanism. >> >> Signed-off-by: Marc Zyngier <maz@kernel.org> > > Before GICv4.1, we use vlpi_count to evaluate whether the vPE has been > mapped on the specified ITS, and use this refcount to only issue VMOVP > to those involved ITSes. It's broken after this patch. > > We may need to re-evaluate "whether the vPE is mapped" now that we're > at > GICv4.1, otherwise *no* VMOVP will be issued on the v4.1 capable > machine > (I mean those without single VMOVP support). > > What I'm saying is something like below (only an idea, it even can't > compile), any thoughts? > > > diff --git a/drivers/irqchip/irq-gic-v3-its.c > b/drivers/irqchip/irq-gic-v3-its.c > index 2e12bc52e3a2..3450b5e847ca 100644 > --- a/drivers/irqchip/irq-gic-v3-its.c > +++ b/drivers/irqchip/irq-gic-v3-its.c > @@ -198,7 +198,8 @@ static u16 get_its_list(struct its_vm *vm) > if (!is_v4(its)) > continue; > > - if (vm->vlpi_count[its->list_nr]) > + if (vm->vlpi_count[its->list_nr] || > + gic_requires_eager_mapping()) > __set_bit(its->list_nr, &its_list); > } > > @@ -1295,7 +1296,8 @@ static void its_send_vmovp(struct its_vpe *vpe) > if (!is_v4(its)) > continue; > > - if (!vpe->its_vm->vlpi_count[its->list_nr]) > + if (!vpe->its_vm->vlpi_count[its->list_nr] && > + !gic_requires_eager_mapping()) > continue; > > desc.its_vmovp_cmd.col = &its->collections[col_id];
It took me a while to wrap my head around that one, but you're as usual spot on.
The use of gic_requires_eager_mapping() is a bit confusing here, as it isn't so much that the VPE is eagerly mapped, but the predicate on which we evaluate the need for a VMOVP. How about this:
diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c index cd6451e190c9..348f7a909a69 100644 --- a/drivers/irqchip/irq-gic-v3-its.c +++ b/drivers/irqchip/irq-gic-v3-its.c @@ -189,6 +189,15 @@ static DEFINE_IDA(its_vpeid_ida); #define gic_data_rdist_rd_base() (gic_data_rdist()->rd_base) #define gic_data_rdist_vlpi_base() (gic_data_rdist_rd_base() + SZ_128K)
+/* + * Skip ITSs that have no vLPIs mapped, unless we're on GICv4.1, as we + * always have vSGIs mapped. + */ +static bool require_its_list_vmovp(struct its_vm *vm, struct its_node *its) +{ + return (gic_rdists->has_rvpeid || vm->vlpi_count[its->list_nr]); +} + static u16 get_its_list(struct its_vm *vm) { struct its_node *its; @@ -198,7 +207,7 @@ static u16 get_its_list(struct its_vm *vm) if (!is_v4(its)) continue;
- if (vm->vlpi_count[its->list_nr]) + if (require_its_list_vmovp(vm, its)) __set_bit(its->list_nr, &its_list); }
@@ -1295,7 +1304,7 @@ static void its_send_vmovp(struct its_vpe *vpe) if (!is_v4(its)) continue;
- if (!vpe->its_vm->vlpi_count[its->list_nr]) + if (!require_its_list_vmovp(vpe->its_vm, its)) continue;
desc.its_vmovp_cmd.col = &its->collections[col_id];
Thanks,
M. -- Jazz is not dead. It just smells funny...
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