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Tue, 14 Dec 2021 18:13:12 +0000 (GMT) Message-ID: <6472fa11-09f4-3e0f-dbec-cf76bcf342c4@linux.ibm.com> Date: Tue, 14 Dec 2021 13:13:11 -0500 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.3.0 Subject: Re: [PATCH 22/32] 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: <20211207205743.150299-1-mjrosato@linux.ibm.com> <20211207205743.150299-23-mjrosato@linux.ibm.com> From: Matthew Rosato In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: s6IONFe6IMq3KCUvLOt22jH7LD4LnVxY X-Proofpoint-GUID: CMPzJUg5HEFSct7Fct0hdJg-tTBGf_yZ X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.790,Hydra:6.0.425,FMLib:17.11.62.513 definitions=2021-12-14_07,2021-12-14_01,2021-12-02_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 mlxlogscore=999 clxscore=1015 bulkscore=0 phishscore=0 suspectscore=0 lowpriorityscore=0 mlxscore=0 malwarescore=0 adultscore=0 spamscore=0 impostorscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2110150000 definitions=main-2112140098 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/14/21 12:46 PM, Pierre Morel wrote: > > > On 12/7/21 21:57, 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             | 133 ++++++++++++++++++++++++++++++++ >>   arch/s390/kvm/pci.h             |   2 + >>   4 files changed, 152 insertions(+) >> >> diff --git a/arch/s390/include/asm/kvm_pci.h >> b/arch/s390/include/asm/kvm_pci.h >> index 54a0afdbe7d0..254275399f21 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; >> +}; >>   struct kvm_zdev { >>       struct zpci_dev *zdev; >>       struct kvm *kvm; >> +    struct kvm_zdev_ioat ioat; >>       struct zpci_fib fib; >>   }; >> @@ -33,6 +43,11 @@ extern int kvm_s390_pci_aif_enable(struct zpci_dev >> *zdev, struct zpci_fib *fib, >>                      bool assist); >>   extern int kvm_s390_pci_aif_disable(struct zpci_dev *zdev); >> +extern int kvm_s390_pci_ioat_probe(struct zpci_dev *zdev); >> +extern int kvm_s390_pci_ioat_enable(struct zpci_dev *zdev, u64 iota); >> +extern int kvm_s390_pci_ioat_disable(struct zpci_dev *zdev); >> +extern u8 kvm_s390_pci_get_dtsm(struct zpci_dev *zdev); >> + >>   extern int kvm_s390_pci_interp_probe(struct zpci_dev *zdev); >>   extern int kvm_s390_pci_interp_enable(struct zpci_dev *zdev); >>   extern 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 3b8e89d4578a..e1d3c1d3fc8a 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 3a29398dd53b..a1c0c0881332 100644 >> --- a/arch/s390/kvm/pci.c >> +++ b/arch/s390/kvm/pci.c >> @@ -12,6 +12,7 @@ >>   #include >>   #include >>   #include >> +#include >>   #include >>   #include "pci.h" >>   #include "kvm-s390.h" >> @@ -315,6 +316,131 @@ 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) >> +{ >> +    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; >> + >> +    if (!zdev->kzdev || !zdev->kzdev->kvm || zdev->kzdev->ioat.head[0]) >> +        return -EINVAL; > > The only caller already checked zdev->kzdev. I tend to get overzealous with these checks.. > Could we use a macro to replace zdev->kzdev->ioat.head[0] ? > like > #define shadow_pgtbl_initialized zdev->kzdev->ioat.head[0] > > Would be clearer for me. Sure > >> + >> +    /* 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)); In relation to your question below about where things are being pinned... Here the call to gfn_to_page does the pin (this call eventually drives hva_to_pfn for pinning) >> +        if (is_error_page(page)) { >> +            srcu_read_unlock(&kvm->srcu, idx); >> +            rc = -EIO; >> +            goto out; >> +        } >> +        iaddr = page_to_virt(page) + (gpa & ~PAGE_MASK); >> +        ioat->head[i] = (unsigned long *)iaddr; ^^ here we store what was pinned above in ioat->head[] and can use it later for unpinning. But looking again now I think for the is_error_page() case above here I should also be going to unpin: to cleanup in case we were somewhere in the middle of the loop and so have some pages pinned already. >> +        gpa += PAGE_SIZE; >> +    } >> +    srcu_read_unlock(&kvm->srcu, idx); >> + >> +    zdev->kzdev->ioat.seg = kcalloc(ZPCI_TABLE_ENTRIES_PAGES, >> +                    sizeof(unsigned long *), GFP_KERNEL); >> +    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; >> + >> +free_seg: >> +    kfree(zdev->kzdev->ioat.seg); >> +unpin: >> +    for (i = 0; i < ZPCI_TABLE_PAGES; i++) { >> +        kvm_release_pfn_dirty((u64)ioat->head[i] >> PAGE_SHIFT); > > I did not find when the pages are pinned. See above. > >> +        ioat->head[i] = 0; >> +    } >> +    mutex_unlock(&ioat->lock); >> +    return -ENOMEM; >> +} >> +EXPORT_SYMBOL_GPL(kvm_s390_pci_ioat_enable); >> + > > ...snip... >> >