Messages in this thread | | | Date | Wed, 26 Jan 2022 09:30:56 +0100 | Subject | Re: [PATCH v2 20/30] KVM: s390: pci: provide routines for enabling/disabling IOAT assist | From | Pierre Morel <> |
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On 1/25/22 15:47, Matthew Rosato wrote: > 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)
I thought the check could be done even if the userspace is not associated with KVM. But of course OK if Alex asked I would have missed some point.
-- Pierre Morel IBM Lab Boeblingen
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