| Message ID | 1606960706-21274-1-git-send-email-igor.druzhinin@citrix.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [v2,1/2] x86/IRQ: make max number of guests for a shared IRQ configurable | expand |
On 03.12.2020 02:58, Igor Druzhinin wrote: > --- a/docs/misc/xen-command-line.pandoc > +++ b/docs/misc/xen-command-line.pandoc > @@ -1641,6 +1641,15 @@ This option is ignored in **pv-shim** mode. > ### nr_irqs (x86) > > `= <integer>` > > +### irq_max_guests (x86) As a rule of thumb, new options want to use - instead of _ as separators. There was a respective discussion quite some time ago. My patch to treat - and _ equally when parsing options wasn't liked by Andrew ... > @@ -435,6 +439,9 @@ int __init init_irq_data(void) > for ( ; irq < nr_irqs; irq++ ) > irq_to_desc(irq)->irq = irq; > > + if ( !irq_max_guests || irq_max_guests > 255) The 255 is a consequence of the struct field being u8, aiui? There should be a direct connection between the two, i.e. when changing the underlying property preferably only one place should require touching (possible e.g. by converting to a bit field with its width established via a #define), or comments on either side should point at the other one. Also as a nit, there's a blank missing ahead of the closing paren. > @@ -1564,7 +1570,8 @@ int pirq_guest_bind(struct vcpu *v, struct pirq *pirq, int will_share) > if ( newaction == NULL ) > { > spin_unlock_irq(&desc->lock); > - if ( (newaction = xmalloc(irq_guest_action_t)) != NULL && > + if ( (newaction = xmalloc_bytes(sizeof(irq_guest_action_t) + > + irq_max_guests * sizeof(action->guest[0]))) != NULL && As said in the (later) reply to v1, please try to make use of xmalloc_flex_struct() here. > @@ -1633,11 +1640,11 @@ int pirq_guest_bind(struct vcpu *v, struct pirq *pirq, int will_share) > goto retry; > } > > - if ( action->nr_guests == IRQ_MAX_GUESTS ) > + if ( action->nr_guests == irq_max_guests ) > { > printk(XENLOG_G_INFO "Cannot bind IRQ%d to dom%d. " > - "Already at max share.\n", > - pirq->pirq, v->domain->domain_id); > + "Already at max share %u, increase with irq_max_guests= option.\n", > + pirq->pirq, v->domain->domain_id, irq_max_guests); If you already need to largely redo this printk(), please - switch to %pd at the same time, - don't have the format string extend across multiple lines, - preferably avoid to use full stops (we don't use any in the vast majority of log messages), e.g. by making it "cannot bind IRQ%d to %pd, already at max share %u (increase with irq-max-guests= option)", if you want to stay close to the original wording (I think this could be expressed more compactly as well). Jan
On 03.12.2020 02:58, Igor Druzhinin wrote: > --- a/docs/misc/xen-command-line.pandoc > +++ b/docs/misc/xen-command-line.pandoc > @@ -1641,6 +1641,15 @@ This option is ignored in **pv-shim** mode. > ### nr_irqs (x86) > > `= <integer>` > > +### irq_max_guests (x86) > +> `= <integer>` > + > +> Default: `16` > + > +Maximum number of guests IRQ could be shared between, i.e. a limit on > +the number of guests it is possible to start each having assigned a device > +sharing a common interrupt line. Accepts values between 1 and 255. Reading through this again, could "IRQ" be expanded to "any individual IRQ" or some such? Jan
diff --git a/docs/misc/xen-command-line.pandoc b/docs/misc/xen-command-line.pandoc index b4a0d60..f5f230c 100644 --- a/docs/misc/xen-command-line.pandoc +++ b/docs/misc/xen-command-line.pandoc @@ -1641,6 +1641,15 @@ This option is ignored in **pv-shim** mode. ### nr_irqs (x86) > `= <integer>` +### irq_max_guests (x86) +> `= <integer>` + +> Default: `16` + +Maximum number of guests IRQ could be shared between, i.e. a limit on +the number of guests it is possible to start each having assigned a device +sharing a common interrupt line. Accepts values between 1 and 255. + ### numa (x86) > `= on | off | fake=<integer> | noacpi` diff --git a/xen/arch/x86/irq.c b/xen/arch/x86/irq.c index 8d1f9a9..5ae9846 100644 --- a/xen/arch/x86/irq.c +++ b/xen/arch/x86/irq.c @@ -42,6 +42,10 @@ integer_param("nr_irqs", nr_irqs); int __read_mostly opt_irq_vector_map = OPT_IRQ_VECTOR_MAP_DEFAULT; custom_param("irq_vector_map", parse_irq_vector_map_param); +/* Max number of guests IRQ could be shared with */ +static unsigned int __read_mostly irq_max_guests; +integer_param("irq_max_guests", irq_max_guests); + vmask_t global_used_vector_map; struct irq_desc __read_mostly *irq_desc = NULL; @@ -435,6 +439,9 @@ int __init init_irq_data(void) for ( ; irq < nr_irqs; irq++ ) irq_to_desc(irq)->irq = irq; + if ( !irq_max_guests || irq_max_guests > 255) + irq_max_guests = 16; + #ifdef CONFIG_PV /* Never allocate the hypercall vector or Linux/BSD fast-trap vector. */ set_bit(LEGACY_SYSCALL_VECTOR, used_vectors); @@ -1028,7 +1035,6 @@ int __init setup_irq(unsigned int irq, unsigned int irqflags, * HANDLING OF GUEST-BOUND PHYSICAL IRQS */ -#define IRQ_MAX_GUESTS 7 typedef struct { u8 nr_guests; u8 in_flight; @@ -1039,7 +1045,7 @@ typedef struct { #define ACKTYPE_EOI 2 /* EOI on the CPU that was interrupted */ cpumask_var_t cpu_eoi_map; /* CPUs that need to EOI this interrupt */ struct timer eoi_timer; - struct domain *guest[IRQ_MAX_GUESTS]; + struct domain *guest[]; } irq_guest_action_t; /* @@ -1564,7 +1570,8 @@ int pirq_guest_bind(struct vcpu *v, struct pirq *pirq, int will_share) if ( newaction == NULL ) { spin_unlock_irq(&desc->lock); - if ( (newaction = xmalloc(irq_guest_action_t)) != NULL && + if ( (newaction = xmalloc_bytes(sizeof(irq_guest_action_t) + + irq_max_guests * sizeof(action->guest[0]))) != NULL && zalloc_cpumask_var(&newaction->cpu_eoi_map) ) goto retry; xfree(newaction); @@ -1633,11 +1640,11 @@ int pirq_guest_bind(struct vcpu *v, struct pirq *pirq, int will_share) goto retry; } - if ( action->nr_guests == IRQ_MAX_GUESTS ) + if ( action->nr_guests == irq_max_guests ) { printk(XENLOG_G_INFO "Cannot bind IRQ%d to dom%d. " - "Already at max share.\n", - pirq->pirq, v->domain->domain_id); + "Already at max share %u, increase with irq_max_guests= option.\n", + pirq->pirq, v->domain->domain_id, irq_max_guests); rc = -EBUSY; goto unlock_out; }
... and increase the default to 16. Current limit of 7 is too restrictive for modern systems where one GSI could be shared by potentially many PCI INTx sources where each of them corresponds to a device passed through to its own guest. Some systems do not apply due dilligence in swizzling INTx links in case e.g. INTA is declared as interrupt pin for the majority of PCI devices behind a single router, resulting in overuse of a GSI. Introduce a new command line option to configure that limit and dynamically allocate an array of the necessary size. Set the default size now to 16 which is higher than 7 but could later be increased even more if necessary. Signed-off-by: Igor Druzhinin <igor.druzhinin@citrix.com> --- Changes in v2: - introduced a command line option as suggested - set the default limit to 16 for now --- docs/misc/xen-command-line.pandoc | 9 +++++++++ xen/arch/x86/irq.c | 19 +++++++++++++------ 2 files changed, 22 insertions(+), 6 deletions(-)