Messages in this thread | | | Date | Tue, 25 Jan 2022 09:47:55 -0500 | Subject | Re: [PATCH v2 20/30] KVM: s390: pci: provide routines for enabling/disabling IOAT assist | From | Matthew Rosato <> |
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On 1/25/22 8:29 AM, Pierre Morel wrote: > > > 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@linux.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? >
OK. The lock is meant to protect the contents of kvm_zdev_ioat -- I'll think of something to describe it.
>> +}; >> 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. >
We probably don't need to check for the kzdev because the caller already did this, agreed there.
But as for checking the kvm association, Alex asked for this in a comment to v1 (comment was against one of the vfio patches that call these routines) -- The reason being the probe comes from a userspace request and can be against any vfio-pci(-zdev) device at any time, and there's no point in proceeding if this device is not associated with a KVM guest -- It's possible for the KVM notifier to also pass a null KVM address -- so I think it's better to just be sure here. In a well-behaved environment we would never see this (so, another case for an s390dbf entry)
>> + 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
Agree based on the changes below
> >> + >> + 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 ?
Ah, right, in case we hit this error somewhere in the middle of the loop.
> >> + } >> + 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 = ... > ?
Yep, would be fine (seems I forgot about the local *ioat here)
> >> + 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 ?
Yes, we can do that now that we don't goto out: after is_error_page
> >> + >> +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;
And yes, agreed, now that we come here for other reasons (-EIO) we must return rc here and also set rc=-ENOMEM as you say for the kfree case above.
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