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Message-ID: <95df349e-3b8d-57b4-6e07-ba80f685d4f1@linux.ibm.com>
Date: Tue, 4 Oct 2022 12:20:47 -0400
From: Matthew Rosato <mjrosato@...ux.ibm.com>
To: Niklas Schnelle <schnelle@...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: Re: [PATCH v4 2/5] iommu/s390: Get rid of s390_domain_device
On 10/4/22 8:07 AM, Niklas Schnelle wrote:
> The struct s390_domain_device serves the sole purpose as list entry for
> the devices list of a struct s390_domain. As it contains no additional
> information besides a list_head and a pointer to the struct zpci_dev we
> can simplify things and just thread the device list through struct
> zpci_dev directly. This removes the need to allocate during domain
> attach and gets rid of one level of indirection during mapping
> operations.
>
> Reviewed-by: Jason Gunthorpe <jgg@...dia.com>
> Signed-off-by: Niklas Schnelle <schnelle@...ux.ibm.com>
Reviewed-by: Matthew Rosato <mjrosato@...ux.ibm.com>
> ---
> arch/s390/include/asm/pci.h | 1 +
> drivers/iommu/s390-iommu.c | 45 ++++++++-----------------------------
> 2 files changed, 10 insertions(+), 36 deletions(-)
>
> diff --git a/arch/s390/include/asm/pci.h b/arch/s390/include/asm/pci.h
> index 108e732d7b14..15f8714ca9b7 100644
> --- a/arch/s390/include/asm/pci.h
> +++ b/arch/s390/include/asm/pci.h
> @@ -117,6 +117,7 @@ struct zpci_bus {
> struct zpci_dev {
> struct zpci_bus *zbus;
> struct list_head entry; /* list of all zpci_devices, needed for hotplug, etc. */
> + struct list_head iommu_list;
> struct kref kref;
> struct hotplug_slot hotplug_slot;
>
> diff --git a/drivers/iommu/s390-iommu.c b/drivers/iommu/s390-iommu.c
> index 0f58e897bc95..6f87dd4b85af 100644
> --- a/drivers/iommu/s390-iommu.c
> +++ b/drivers/iommu/s390-iommu.c
> @@ -29,11 +29,6 @@ struct s390_domain {
> spinlock_t list_lock;
> };
>
> -struct s390_domain_device {
> - struct list_head list;
> - struct zpci_dev *zdev;
> -};
> -
> static struct s390_domain *to_s390_domain(struct iommu_domain *dom)
> {
> return container_of(dom, struct s390_domain, domain);
> @@ -87,21 +82,13 @@ static void s390_domain_free(struct iommu_domain *domain)
> static void __s390_iommu_detach_device(struct zpci_dev *zdev)
> {
> struct s390_domain *s390_domain = zdev->s390_domain;
> - struct s390_domain_device *domain_device, *tmp;
> unsigned long flags;
>
> if (!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;
> - }
> - }
> + list_del_init(&zdev->iommu_list);
> spin_unlock_irqrestore(&s390_domain->list_lock, flags);
>
> zpci_unregister_ioat(zdev, 0);
> @@ -114,17 +101,12 @@ static int s390_iommu_attach_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;
> unsigned long flags;
> - int cc, rc = 0;
> + int cc;
>
> if (!zdev)
> return -ENODEV;
>
> - domain_device = kzalloc(sizeof(*domain_device), GFP_KERNEL);
> - if (!domain_device)
> - return -ENOMEM;
> -
> if (zdev->s390_domain)
> __s390_iommu_detach_device(zdev);
> else if (zdev->dma_table)
> @@ -133,10 +115,8 @@ static int s390_iommu_attach_device(struct iommu_domain *domain,
> 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_free;
> - }
> + if (cc)
> + return -EIO;
>
> spin_lock_irqsave(&s390_domain->list_lock, flags);
> /* First device defines the DMA range limits */
> @@ -147,21 +127,14 @@ static int s390_iommu_attach_device(struct iommu_domain *domain,
> /* Allow only devices with identical DMA range limits */
> } else if (domain->geometry.aperture_start != zdev->start_dma ||
> domain->geometry.aperture_end != zdev->end_dma) {
> - rc = -EINVAL;
> spin_unlock_irqrestore(&s390_domain->list_lock, flags);
> - goto out_free;
> + return -EINVAL;
> }
> - domain_device->zdev = zdev;
> zdev->s390_domain = s390_domain;
> - list_add(&domain_device->list, &s390_domain->devices);
> + list_add(&zdev->iommu_list, &s390_domain->devices);
> spin_unlock_irqrestore(&s390_domain->list_lock, flags);
>
> return 0;
> -
> -out_free:
> - kfree(domain_device);
> -
> - return rc;
> }
>
> static void s390_iommu_detach_device(struct iommu_domain *domain,
> @@ -198,10 +171,10 @@ static int s390_iommu_update_trans(struct s390_domain *s390_domain,
> phys_addr_t pa, dma_addr_t dma_addr,
> size_t size, int flags)
> {
> - struct s390_domain_device *domain_device;
> phys_addr_t page_addr = pa & PAGE_MASK;
> dma_addr_t start_dma_addr = dma_addr;
> unsigned long irq_flags, nr_pages, i;
> + struct zpci_dev *zdev;
> unsigned long *entry;
> int rc = 0;
>
> @@ -226,8 +199,8 @@ static int s390_iommu_update_trans(struct s390_domain *s390_domain,
> }
>
> spin_lock(&s390_domain->list_lock);
> - list_for_each_entry(domain_device, &s390_domain->devices, list) {
> - rc = zpci_refresh_trans((u64) domain_device->zdev->fh << 32,
> + list_for_each_entry(zdev, &s390_domain->devices, iommu_list) {
> + rc = zpci_refresh_trans((u64)zdev->fh << 32,
> start_dma_addr, nr_pages * PAGE_SIZE);
> if (rc)
> break;
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