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Message-ID: <12b9fba1-38b4-057d-49f4-969f2e7e1be3@linux.ibm.com>
Date: Tue, 25 Jan 2022 14:29:57 +0100
From: Pierre Morel <pmorel@...ux.ibm.com>
To: Matthew Rosato <mjrosato@...ux.ibm.com>, linux-s390@...r.kernel.org
Cc: alex.williamson@...hat.com, cohuck@...hat.com,
schnelle@...ux.ibm.com, farman@...ux.ibm.com,
borntraeger@...ux.ibm.com, hca@...ux.ibm.com, gor@...ux.ibm.com,
gerald.schaefer@...ux.ibm.com, agordeev@...ux.ibm.com,
frankja@...ux.ibm.com, david@...hat.com, imbrenda@...ux.ibm.com,
vneethv@...ux.ibm.com, oberpar@...ux.ibm.com, freude@...ux.ibm.com,
thuth@...hat.com, pasic@...ux.ibm.com, kvm@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 20/30] KVM: s390: pci: provide routines for
enabling/disabling IOAT assist
On 1/14/22 21:31, Matthew Rosato wrote:
> These routines will be wired into the vfio_pci_zdev ioctl handlers to
> respond to requests to enable / disable a device for PCI I/O Address
> Translation assistance.
>
> Signed-off-by: Matthew Rosato <mjrosato@...ux.ibm.com>
> ---
> arch/s390/include/asm/kvm_pci.h | 15 ++++
> arch/s390/include/asm/pci_dma.h | 2 +
> arch/s390/kvm/pci.c | 139 ++++++++++++++++++++++++++++++++
> arch/s390/kvm/pci.h | 2 +
> 4 files changed, 158 insertions(+)
>
> diff --git a/arch/s390/include/asm/kvm_pci.h b/arch/s390/include/asm/kvm_pci.h
> index 01fe14fffd7a..770849f13a70 100644
> --- a/arch/s390/include/asm/kvm_pci.h
> +++ b/arch/s390/include/asm/kvm_pci.h
> @@ -16,11 +16,21 @@
> #include <linux/kvm_host.h>
> #include <linux/kvm.h>
> #include <linux/pci.h>
> +#include <linux/mutex.h>
> #include <asm/pci_insn.h>
> +#include <asm/pci_dma.h>
> +
> +struct kvm_zdev_ioat {
> + unsigned long *head[ZPCI_TABLE_PAGES];
> + unsigned long **seg;
> + unsigned long ***pt;
> + struct mutex lock;
Can we please rename the mutex ioat_lock to have a unique name easy to
follow for maintenance.
Can you please add a description about when the lock should be used?
> +};
>
> struct kvm_zdev {
> struct zpci_dev *zdev;
> struct kvm *kvm;
> + struct kvm_zdev_ioat ioat;
> struct zpci_fib fib;
> };
>
> @@ -33,6 +43,11 @@ int kvm_s390_pci_aif_enable(struct zpci_dev *zdev, struct zpci_fib *fib,
> bool assist);
> int kvm_s390_pci_aif_disable(struct zpci_dev *zdev);
>
> +int kvm_s390_pci_ioat_probe(struct zpci_dev *zdev);
> +int kvm_s390_pci_ioat_enable(struct zpci_dev *zdev, u64 iota);
> +int kvm_s390_pci_ioat_disable(struct zpci_dev *zdev);
> +u8 kvm_s390_pci_get_dtsm(struct zpci_dev *zdev);
> +
> int kvm_s390_pci_interp_probe(struct zpci_dev *zdev);
> int kvm_s390_pci_interp_enable(struct zpci_dev *zdev);
> int kvm_s390_pci_interp_disable(struct zpci_dev *zdev);
> diff --git a/arch/s390/include/asm/pci_dma.h b/arch/s390/include/asm/pci_dma.h
> index 91e63426bdc5..69e616d0712c 100644
> --- a/arch/s390/include/asm/pci_dma.h
> +++ b/arch/s390/include/asm/pci_dma.h
> @@ -50,6 +50,8 @@ enum zpci_ioat_dtype {
> #define ZPCI_TABLE_ALIGN ZPCI_TABLE_SIZE
> #define ZPCI_TABLE_ENTRY_SIZE (sizeof(unsigned long))
> #define ZPCI_TABLE_ENTRIES (ZPCI_TABLE_SIZE / ZPCI_TABLE_ENTRY_SIZE)
> +#define ZPCI_TABLE_PAGES (ZPCI_TABLE_SIZE >> PAGE_SHIFT)
> +#define ZPCI_TABLE_ENTRIES_PAGES (ZPCI_TABLE_ENTRIES * ZPCI_TABLE_PAGES)
>
> #define ZPCI_TABLE_BITS 11
> #define ZPCI_PT_BITS 8
> diff --git a/arch/s390/kvm/pci.c b/arch/s390/kvm/pci.c
> index 7ed9abc476b6..39c13c25a700 100644
> --- a/arch/s390/kvm/pci.c
> +++ b/arch/s390/kvm/pci.c
> @@ -13,12 +13,15 @@
> #include <asm/pci.h>
> #include <asm/pci_insn.h>
> #include <asm/pci_io.h>
> +#include <asm/pci_dma.h>
> #include <asm/sclp.h>
> #include "pci.h"
> #include "kvm-s390.h"
>
> struct zpci_aift *aift;
>
> +#define shadow_ioat_init zdev->kzdev->ioat.head[0]
> +
> static inline int __set_irq_noiib(u16 ctl, u8 isc)
> {
> union zpci_sic_iib iib = {{0}};
> @@ -344,6 +347,135 @@ int kvm_s390_pci_aif_disable(struct zpci_dev *zdev)
> }
> EXPORT_SYMBOL_GPL(kvm_s390_pci_aif_disable);
>
> +int kvm_s390_pci_ioat_probe(struct zpci_dev *zdev)
> +{
> + /* Must have a KVM association registered */
may be add something like : "The ioat structure is embeded in kzdev"
> + if (!zdev->kzdev || !zdev->kzdev->kvm)
Why do we need to check for kvm ?
Having kzdev is already tested by the unique caller.
> + return -EINVAL;
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(kvm_s390_pci_ioat_probe);
> +
> +int kvm_s390_pci_ioat_enable(struct zpci_dev *zdev, u64 iota)
> +{
> + gpa_t gpa = (gpa_t)(iota & ZPCI_RTE_ADDR_MASK);
> + struct kvm_zdev_ioat *ioat;
> + struct page *page;
> + struct kvm *kvm;
> + unsigned int idx;
> + void *iaddr;
> + int i, rc = 0;
no need to initialize rc
> +
> + if (shadow_ioat_init)
> + return -EINVAL;
> +
> + /* Ensure supported type specified */
> + if ((iota & ZPCI_IOTA_RTTO_FLAG) != ZPCI_IOTA_RTTO_FLAG)
> + return -EINVAL;
> +
> + kvm = zdev->kzdev->kvm;
> + ioat = &zdev->kzdev->ioat;
> + mutex_lock(&ioat->lock);
> + idx = srcu_read_lock(&kvm->srcu);
> + for (i = 0; i < ZPCI_TABLE_PAGES; i++) {
> + page = gfn_to_page(kvm, gpa_to_gfn(gpa));
> + if (is_error_page(page)) {
> + srcu_read_unlock(&kvm->srcu, idx);
> + rc = -EIO;
> + goto out;
goto unpin ?
> + }
> + iaddr = page_to_virt(page) + (gpa & ~PAGE_MASK);
> + ioat->head[i] = (unsigned long *)iaddr;
> + gpa += PAGE_SIZE;
> + }
> + srcu_read_unlock(&kvm->srcu, idx);
> +
> + zdev->kzdev->ioat.seg = kcalloc(ZPCI_TABLE_ENTRIES_PAGES,
> + sizeof(unsigned long *), GFP_KERNEL);
What about:
ioat->seg = kcalloc(ZPCI_TABLE_ENTRIES_PAGES,
sizeof(*ioat->seg), GFP_KERNEL);
if (!ioat->seg)
...
ioat->pt = ...
?
> + if (!zdev->kzdev->ioat.seg)
> + goto unpin;
> + zdev->kzdev->ioat.pt = kcalloc(ZPCI_TABLE_ENTRIES,
> + sizeof(unsigned long **), GFP_KERNEL);
> + if (!zdev->kzdev->ioat.pt)
> + goto free_seg;
> +
> +out:
> + mutex_unlock(&ioat->lock);
> + return rc;
return 0 ?
> +
> +free_seg:
> + kfree(zdev->kzdev->ioat.seg);
kfree(ioat->seg) ?
rc = -ENOMEM;
> +unpin:
> + for (i = 0; i < ZPCI_TABLE_PAGES; i++) {
> + kvm_release_pfn_dirty((u64)ioat->head[i] >> PAGE_SHIFT);
> + ioat->head[i] = 0;
> + }
> + mutex_unlock(&ioat->lock);
> + return -ENOMEM;
return rc;
> +}
...snip...
--
Pierre Morel
IBM Lab Boeblingen
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