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Message-Id: <20220929153302.3195115-2-schnelle@linux.ibm.com>
Date: Thu, 29 Sep 2022 17:32:58 +0200
From: Niklas Schnelle <schnelle@...ux.ibm.com>
To: Matthew Rosato <mjrosato@...ux.ibm.com>,
Pierre Morel <pmorel@...ux.ibm.com>, iommu@...ts.linux.dev
Cc: linux-s390@...r.kernel.org, borntraeger@...ux.ibm.com,
hca@...ux.ibm.com, gor@...ux.ibm.com,
gerald.schaefer@...ux.ibm.com, agordeev@...ux.ibm.com,
svens@...ux.ibm.com, joro@...tes.org, will@...nel.org,
robin.murphy@....com, jgg@...dia.com, linux-kernel@...r.kernel.org
Subject: [PATCH v3 1/5] iommu/s390: Fix duplicate domain attachments
Since commit fa7e9ecc5e1c ("iommu/s390: Tolerate repeat attach_dev
calls") we can end up with duplicates in the list of devices attached to
a domain. This is inefficient and confusing since only one domain can
actually be in control of the IOMMU translations for a device. Fix this
by detaching the device from the previous domain, if any, on attach.
Add a WARN_ON() in case we still have attached devices on freeing the
domain. While here remove the re-attach on failure dance as it was
determined to be unlikely to help and may confuse debug and recovery.
Fixes: fa7e9ecc5e1c ("iommu/s390: Tolerate repeat attach_dev calls")
Signed-off-by: Niklas Schnelle <schnelle@...ux.ibm.com>
---
Changes since v2:
- Make __s390_iommu_detach_device() return void (Jason)
- Remove superfluous locking when we're freeing anyway (Jason)
- Remove the re-attach on failure dance as it is unlikely to help
and complicates debug and recovery (Jason)
- Ignore attempts to detach from domain that the device is no longer
attached to.
drivers/iommu/s390-iommu.c | 77 +++++++++++++++++---------------------
1 file changed, 34 insertions(+), 43 deletions(-)
diff --git a/drivers/iommu/s390-iommu.c b/drivers/iommu/s390-iommu.c
index c898bcbbce11..6fcb64e4b5e6 100644
--- a/drivers/iommu/s390-iommu.c
+++ b/drivers/iommu/s390-iommu.c
@@ -79,10 +79,36 @@ static void s390_domain_free(struct iommu_domain *domain)
{
struct s390_domain *s390_domain = to_s390_domain(domain);
+ WARN_ON(!list_empty(&s390_domain->devices));
dma_cleanup_tables(s390_domain->dma_table);
kfree(s390_domain);
}
+static void __s390_iommu_detach_device(struct s390_domain *s390_domain,
+ struct zpci_dev *zdev)
+{
+ struct s390_domain_device *domain_device, *tmp;
+ unsigned long flags;
+
+ if (!zdev || zdev->s390_domain != s390_domain)
+ return;
+
+ spin_lock_irqsave(&s390_domain->list_lock, flags);
+ list_for_each_entry_safe(domain_device, tmp, &s390_domain->devices,
+ list) {
+ if (domain_device->zdev == zdev) {
+ list_del(&domain_device->list);
+ kfree(domain_device);
+ break;
+ }
+ }
+ spin_unlock_irqrestore(&s390_domain->list_lock, flags);
+
+ zpci_unregister_ioat(zdev, 0);
+ zdev->s390_domain = NULL;
+ zdev->dma_table = NULL;
+}
+
static int s390_iommu_attach_device(struct iommu_domain *domain,
struct device *dev)
{
@@ -90,7 +116,7 @@ static int s390_iommu_attach_device(struct iommu_domain *domain,
struct zpci_dev *zdev = to_zpci_dev(dev);
struct s390_domain_device *domain_device;
unsigned long flags;
- int cc, rc;
+ int cc, rc = 0;
if (!zdev)
return -ENODEV;
@@ -99,23 +125,17 @@ static int s390_iommu_attach_device(struct iommu_domain *domain,
if (!domain_device)
return -ENOMEM;
- if (zdev->dma_table && !zdev->s390_domain) {
- cc = zpci_dma_exit_device(zdev);
- if (cc) {
- rc = -EIO;
- goto out_free;
- }
- }
-
if (zdev->s390_domain)
- zpci_unregister_ioat(zdev, 0);
+ __s390_iommu_detach_device(zdev->s390_domain, zdev);
+ else if (zdev->dma_table)
+ zpci_dma_exit_device(zdev);
zdev->dma_table = s390_domain->dma_table;
cc = zpci_register_ioat(zdev, 0, zdev->start_dma, zdev->end_dma,
virt_to_phys(zdev->dma_table));
if (cc) {
rc = -EIO;
- goto out_restore;
+ goto out_free;
}
spin_lock_irqsave(&s390_domain->list_lock, flags);
@@ -129,7 +149,7 @@ static int s390_iommu_attach_device(struct iommu_domain *domain,
domain->geometry.aperture_end != zdev->end_dma) {
rc = -EINVAL;
spin_unlock_irqrestore(&s390_domain->list_lock, flags);
- goto out_restore;
+ goto out_free;
}
domain_device->zdev = zdev;
zdev->s390_domain = s390_domain;
@@ -138,14 +158,6 @@ static int s390_iommu_attach_device(struct iommu_domain *domain,
return 0;
-out_restore:
- if (!zdev->s390_domain) {
- zpci_dma_init_device(zdev);
- } else {
- zdev->dma_table = zdev->s390_domain->dma_table;
- zpci_register_ioat(zdev, 0, zdev->start_dma, zdev->end_dma,
- virt_to_phys(zdev->dma_table));
- }
out_free:
kfree(domain_device);
@@ -157,30 +169,9 @@ static void s390_iommu_detach_device(struct iommu_domain *domain,
{
struct s390_domain *s390_domain = to_s390_domain(domain);
struct zpci_dev *zdev = to_zpci_dev(dev);
- struct s390_domain_device *domain_device, *tmp;
- unsigned long flags;
- int found = 0;
-
- if (!zdev)
- return;
-
- spin_lock_irqsave(&s390_domain->list_lock, flags);
- list_for_each_entry_safe(domain_device, tmp, &s390_domain->devices,
- list) {
- if (domain_device->zdev == zdev) {
- list_del(&domain_device->list);
- kfree(domain_device);
- found = 1;
- break;
- }
- }
- spin_unlock_irqrestore(&s390_domain->list_lock, flags);
- if (found && (zdev->s390_domain == s390_domain)) {
- zdev->s390_domain = NULL;
- zpci_unregister_ioat(zdev, 0);
- zpci_dma_init_device(zdev);
- }
+ __s390_iommu_detach_device(s390_domain, zdev);
+ zpci_dma_init_device(zdev);
}
static struct iommu_device *s390_iommu_probe_device(struct device *dev)
--
2.34.1
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