From: Juergen Gross jgross@suse.com
commit c2711441bc961b37bba0615dd7135857d189035f upstream.
In order to reduce the chance for the system becoming unresponsive due to event storms triggered by a misbehaving pcifront use the lateeoi irq binding for pciback and unmask the event channel only just before leaving the event handling function.
Restructure the handling to support that scheme. Basically an event can come in for two reasons: either a normal request for a pciback action, which is handled in a worker, or in case the guest has finished an AER request which was requested by pciback.
When an AER request is issued to the guest and a normal pciback action is currently active issue an EOI early in order to be able to receive another event when the AER request has been finished by the guest.
Let the worker processing the normal requests run until no further request is pending, instead of starting a new worker ion that case. Issue the EOI only just before leaving the worker.
This scheme allows to drop calling the generic function xen_pcibk_test_and_schedule_op() after processing of any request as the handling of both request types is now separated more cleanly.
This is part of XSA-332.
Cc: stable@vger.kernel.org Reported-by: Julien Grall julien@xen.org Signed-off-by: Juergen Gross jgross@suse.com Reviewed-by: Jan Beulich jbeulich@suse.com Reviewed-by: Wei Liu wl@xen.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/xen/xen-pciback/pci_stub.c | 14 ++++----- drivers/xen/xen-pciback/pciback.h | 12 +++++++- drivers/xen/xen-pciback/pciback_ops.c | 48 ++++++++++++++++++++++++++-------- drivers/xen/xen-pciback/xenbus.c | 2 - 4 files changed, 56 insertions(+), 20 deletions(-)
--- a/drivers/xen/xen-pciback/pci_stub.c +++ b/drivers/xen/xen-pciback/pci_stub.c @@ -733,10 +733,17 @@ static pci_ers_result_t common_process(s wmb(); notify_remote_via_irq(pdev->evtchn_irq);
+ /* Enable IRQ to signal "request done". */ + xen_pcibk_lateeoi(pdev, 0); + ret = wait_event_timeout(xen_pcibk_aer_wait_queue, !(test_bit(_XEN_PCIB_active, (unsigned long *) &sh_info->flags)), 300*HZ);
+ /* Enable IRQ for pcifront request if not already active. */ + if (!test_bit(_PDEVF_op_active, &pdev->flags)) + xen_pcibk_lateeoi(pdev, 0); + if (!ret) { if (test_bit(_XEN_PCIB_active, (unsigned long *)&sh_info->flags)) { @@ -750,13 +757,6 @@ static pci_ers_result_t common_process(s } clear_bit(_PCIB_op_pending, (unsigned long *)&pdev->flags);
- if (test_bit(_XEN_PCIF_active, - (unsigned long *)&sh_info->flags)) { - dev_dbg(&psdev->dev->dev, - "schedule pci_conf service in " DRV_NAME "\n"); - xen_pcibk_test_and_schedule_op(psdev->pdev); - } - res = (pci_ers_result_t)aer_op->err; return res; } --- a/drivers/xen/xen-pciback/pciback.h +++ b/drivers/xen/xen-pciback/pciback.h @@ -14,6 +14,7 @@ #include <linux/spinlock.h> #include <linux/workqueue.h> #include <linux/atomic.h> +#include <xen/events.h> #include <xen/interface/io/pciif.h>
#define DRV_NAME "xen-pciback" @@ -27,6 +28,8 @@ struct pci_dev_entry { #define PDEVF_op_active (1<<(_PDEVF_op_active)) #define _PCIB_op_pending (1) #define PCIB_op_pending (1<<(_PCIB_op_pending)) +#define _EOI_pending (2) +#define EOI_pending (1<<(_EOI_pending))
struct xen_pcibk_device { void *pci_dev_data; @@ -182,12 +185,17 @@ static inline void xen_pcibk_release_dev irqreturn_t xen_pcibk_handle_event(int irq, void *dev_id); void xen_pcibk_do_op(struct work_struct *data);
+static inline void xen_pcibk_lateeoi(struct xen_pcibk_device *pdev, + unsigned int eoi_flag) +{ + if (test_and_clear_bit(_EOI_pending, &pdev->flags)) + xen_irq_lateeoi(pdev->evtchn_irq, eoi_flag); +} + int xen_pcibk_xenbus_register(void); void xen_pcibk_xenbus_unregister(void);
extern int verbose_request; - -void xen_pcibk_test_and_schedule_op(struct xen_pcibk_device *pdev); #endif
/* Handles shared IRQs that can to device domain and control domain. */ --- a/drivers/xen/xen-pciback/pciback_ops.c +++ b/drivers/xen/xen-pciback/pciback_ops.c @@ -297,26 +297,41 @@ int xen_pcibk_disable_msix(struct xen_pc return 0; } #endif + +static inline bool xen_pcibk_test_op_pending(struct xen_pcibk_device *pdev) +{ + return test_bit(_XEN_PCIF_active, + (unsigned long *)&pdev->sh_info->flags) && + !test_and_set_bit(_PDEVF_op_active, &pdev->flags); +} + /* * Now the same evtchn is used for both pcifront conf_read_write request * as well as pcie aer front end ack. We use a new work_queue to schedule * xen_pcibk conf_read_write service for avoiding confict with aer_core * do_recovery job which also use the system default work_queue */ -void xen_pcibk_test_and_schedule_op(struct xen_pcibk_device *pdev) +static void xen_pcibk_test_and_schedule_op(struct xen_pcibk_device *pdev) { + bool eoi = true; + /* Check that frontend is requesting an operation and that we are not * already processing a request */ - if (test_bit(_XEN_PCIF_active, (unsigned long *)&pdev->sh_info->flags) - && !test_and_set_bit(_PDEVF_op_active, &pdev->flags)) { + if (xen_pcibk_test_op_pending(pdev)) { schedule_work(&pdev->op_work); + eoi = false; } /*_XEN_PCIB_active should have been cleared by pcifront. And also make sure xen_pcibk is waiting for ack by checking _PCIB_op_pending*/ if (!test_bit(_XEN_PCIB_active, (unsigned long *)&pdev->sh_info->flags) && test_bit(_PCIB_op_pending, &pdev->flags)) { wake_up(&xen_pcibk_aer_wait_queue); + eoi = false; } + + /* EOI if there was nothing to do. */ + if (eoi) + xen_pcibk_lateeoi(pdev, XEN_EOI_FLAG_SPURIOUS); }
/* Performing the configuration space reads/writes must not be done in atomic @@ -324,10 +339,8 @@ void xen_pcibk_test_and_schedule_op(stru * use of semaphores). This function is intended to be called from a work * queue in process context taking a struct xen_pcibk_device as a parameter */
-void xen_pcibk_do_op(struct work_struct *data) +static void xen_pcibk_do_one_op(struct xen_pcibk_device *pdev) { - struct xen_pcibk_device *pdev = - container_of(data, struct xen_pcibk_device, op_work); struct pci_dev *dev; struct xen_pcibk_dev_data *dev_data = NULL; struct xen_pci_op *op = &pdev->op; @@ -400,16 +413,31 @@ void xen_pcibk_do_op(struct work_struct smp_mb__before_atomic(); /* /after/ clearing PCIF_active */ clear_bit(_PDEVF_op_active, &pdev->flags); smp_mb__after_atomic(); /* /before/ final check for work */ +}
- /* Check to see if the driver domain tried to start another request in - * between clearing _XEN_PCIF_active and clearing _PDEVF_op_active. - */ - xen_pcibk_test_and_schedule_op(pdev); +void xen_pcibk_do_op(struct work_struct *data) +{ + struct xen_pcibk_device *pdev = + container_of(data, struct xen_pcibk_device, op_work); + + do { + xen_pcibk_do_one_op(pdev); + } while (xen_pcibk_test_op_pending(pdev)); + + xen_pcibk_lateeoi(pdev, 0); }
irqreturn_t xen_pcibk_handle_event(int irq, void *dev_id) { struct xen_pcibk_device *pdev = dev_id; + bool eoi; + + /* IRQs might come in before pdev->evtchn_irq is written. */ + if (unlikely(pdev->evtchn_irq != irq)) + pdev->evtchn_irq = irq; + + eoi = test_and_set_bit(_EOI_pending, &pdev->flags); + WARN(eoi, "IRQ while EOI pending\n");
xen_pcibk_test_and_schedule_op(pdev);
--- a/drivers/xen/xen-pciback/xenbus.c +++ b/drivers/xen/xen-pciback/xenbus.c @@ -123,7 +123,7 @@ static int xen_pcibk_do_attach(struct xe
pdev->sh_info = vaddr;
- err = bind_interdomain_evtchn_to_irqhandler( + err = bind_interdomain_evtchn_to_irqhandler_lateeoi( pdev->xdev->otherend_id, remote_evtchn, xen_pcibk_handle_event, 0, DRV_NAME, pdev); if (err < 0) {