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Tue, 25 Jan 2022 14:47:56 +0000 (GMT) Received: from [9.163.21.206] (unknown [9.163.21.206]) by b03ledav006.gho.boulder.ibm.com (Postfix) with ESMTP; Tue, 25 Jan 2022 14:47:56 +0000 (GMT) Message-ID: <5de7c3ef-9c25-56d3-cc46-e002f8742dbe@linux.ibm.com> Date: Tue, 25 Jan 2022 09:47:55 -0500 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.4.0 Subject: Re: [PATCH v2 20/30] KVM: s390: pci: provide routines for enabling/disabling IOAT assist Content-Language: en-US To: Pierre Morel , linux-s390@vger.kernel.org Cc: alex.williamson@redhat.com, cohuck@redhat.com, schnelle@linux.ibm.com, farman@linux.ibm.com, borntraeger@linux.ibm.com, hca@linux.ibm.com, gor@linux.ibm.com, gerald.schaefer@linux.ibm.com, agordeev@linux.ibm.com, frankja@linux.ibm.com, david@redhat.com, imbrenda@linux.ibm.com, vneethv@linux.ibm.com, oberpar@linux.ibm.com, freude@linux.ibm.com, thuth@redhat.com, pasic@linux.ibm.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org References: <20220114203145.242984-1-mjrosato@linux.ibm.com> <20220114203145.242984-21-mjrosato@linux.ibm.com> <12b9fba1-38b4-057d-49f4-969f2e7e1be3@linux.ibm.com> From: Matthew Rosato In-Reply-To: <12b9fba1-38b4-057d-49f4-969f2e7e1be3@linux.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: -PlSyIzHZkswDFo9yUtdPrsqnSE35ewt X-Proofpoint-ORIG-GUID: U0yGsMqQdu3xmgrVCtVy70vD98jSwD6n X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.816,Hydra:6.0.425,FMLib:17.11.62.513 definitions=2022-01-25_02,2022-01-25_01,2021-12-02_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 clxscore=1015 impostorscore=0 malwarescore=0 bulkscore=0 mlxscore=0 mlxlogscore=999 spamscore=0 lowpriorityscore=0 phishscore=0 adultscore=0 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2201110000 definitions=main-2201250094 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 >> --- >>   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 >>   #include >>   #include >> +#include >>   #include >> +#include >> + >> +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 >>   #include >>   #include >> +#include >>   #include >>   #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.