Re: [PATCH] xen/events: don't use chip_data for legacy IRQs

Any reason this has not made it into 5.4.y and older by now?

This patch is fixing a real problem...

Juergen

On 05.10.20 08:19, Juergen Gross wrote:

Since commit c330fb1ddc0a ("XEN uses irqdesc::irq_data_common::handler_data to store a per interrupt XEN data pointer which contains XEN specific information.") Xen is using the chip_data pointer for storing IRQ specific data. When running as a HVM domain this can result in problems for legacy IRQs, as those might use chip_data for their own purposes.

Use a local array for this purpose in case of legacy IRQs, avoiding the double use.

Fixes: c330fb1ddc0a ("XEN uses irqdesc::irq_data_common::handler_data to store a per interrupt XEN data pointer which contains XEN specific information.") Signed-off-by: Juergen Gross jgross@suse.com Tested-by: Stefan Bader stefan.bader@canonical.com Reviewed-by: Boris Ostrovsky boris.ostrovsky@oracle.com Link: https://lore.kernel.org/r/20200930091614.13660-1-jgross@suse.com

---

This is a backport for stable kernel 5.4.y and older

drivers/xen/events/events_base.c | 29 +++++++++++++++++++++-------- 1 file changed, 21 insertions(+), 8 deletions(-)

diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c index 55f2b834cf13..e402620b8920 100644 --- a/drivers/xen/events/events_base.c +++ b/drivers/xen/events/events_base.c @@ -91,6 +91,8 @@ static bool (*pirq_needs_eoi)(unsigned irq); /* Xen will never allocate port zero for any purpose. */ #define VALID_EVTCHN(chn) ((chn) != 0) +static struct irq_info *legacy_info_ptrs[NR_IRQS_LEGACY];

• static struct irq_chip xen_dynamic_chip; static struct irq_chip xen_percpu_chip; static struct irq_chip xen_pirq_chip;

@@ -155,7 +157,18 @@ int get_evtchn_to_irq(unsigned evtchn) /* Get info for IRQ */ struct irq_info *info_for_irq(unsigned irq) {

• return irq_get_chip_data(irq);

• if (irq < nr_legacy_irqs())

• return legacy_info_ptrs[irq];
  

• else

• return irq_get_chip_data(irq);
  

+}

+static void set_info_for_irq(unsigned int irq, struct irq_info *info) +{

• if (irq < nr_legacy_irqs())

• legacy_info_ptrs[irq] = info;
  

• else

• irq_set_chip_data(irq, info);
  

  }

/* Constructors for packed IRQ information. */ @@ -376,7 +389,7 @@ static void xen_irq_init(unsigned irq) info->type = IRQT_UNBOUND; info->refcnt = -1;

• irq_set_chip_data(irq, info);

• set_info_for_irq(irq, info);

list_add_tail(&info->list, &xen_irq_list_head); } @@ -425,14 +438,14 @@ static int __must_check xen_allocate_irq_gsi(unsigned gsi) static void xen_free_irq(unsigned irq) {

• struct irq_info *info = irq_get_chip_data(irq);

• struct irq_info *info = info_for_irq(irq);

if (WARN_ON(!info)) return; list_del(&info->list);

• irq_set_chip_data(irq, NULL);

• set_info_for_irq(irq, NULL);

WARN_ON(info->refcnt > 0); @@ -602,7 +615,7 @@ EXPORT_SYMBOL_GPL(xen_irq_from_gsi); static void __unbind_from_irq(unsigned int irq) { int evtchn = evtchn_from_irq(irq);

• struct irq_info *info = irq_get_chip_data(irq);

• struct irq_info *info = info_for_irq(irq);

if (info->refcnt > 0) { info->refcnt--; @@ -1106,7 +1119,7 @@ int bind_ipi_to_irqhandler(enum ipi_vector ipi, void unbind_from_irqhandler(unsigned int irq, void *dev_id) {

• struct irq_info *info = irq_get_chip_data(irq);

• struct irq_info *info = info_for_irq(irq);

if (WARN_ON(!info)) return; @@ -1140,7 +1153,7 @@ int evtchn_make_refcounted(unsigned int evtchn) if (irq == -1) return -ENOENT;

• info = irq_get_chip_data(irq);

• info = info_for_irq(irq);

if (!info) return -ENOENT; @@ -1168,7 +1181,7 @@ int evtchn_get(unsigned int evtchn) if (irq == -1) goto done;

• info = irq_get_chip_data(irq);

• info = info_for_irq(irq);

if (!info) goto done;