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[79.178.2.19]) by smtp.gmail.com with ESMTPSA id y5sm6737555qkb.123.2020.03.10.04.12.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 10 Mar 2020 04:12:31 -0700 (PDT) Date: Tue, 10 Mar 2020 07:12:25 -0400 From: "Michael S. Tsirkin" To: Vivek Goyal Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvdimm@lists.01.org, virtio-fs@redhat.com, miklos@szeredi.hu, stefanha@redhat.com, dgilbert@redhat.com, Sebastien Boeuf , kbuild test robot Subject: Re: [PATCH 04/20] virtio: Implement get_shm_region for PCI transport Message-ID: <20200310071043-mutt-send-email-mst@kernel.org> References: <20200304165845.3081-1-vgoyal@redhat.com> <20200304165845.3081-5-vgoyal@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200304165845.3081-5-vgoyal@redhat.com> Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Wed, Mar 04, 2020 at 11:58:29AM -0500, Vivek Goyal wrote: > From: Sebastien Boeuf > > On PCI the shm regions are found using capability entries; > find a region by searching for the capability. > > Signed-off-by: Sebastien Boeuf > Signed-off-by: Dr. David Alan Gilbert > Signed-off-by: kbuild test robot > --- > drivers/virtio/virtio_pci_modern.c | 107 +++++++++++++++++++++++++++++ > include/uapi/linux/virtio_pci.h | 11 ++- > 2 files changed, 117 insertions(+), 1 deletion(-) > > diff --git a/drivers/virtio/virtio_pci_modern.c b/drivers/virtio/virtio_pci_modern.c > index 7abcc50838b8..52f179411015 100644 > --- a/drivers/virtio/virtio_pci_modern.c > +++ b/drivers/virtio/virtio_pci_modern.c > @@ -443,6 +443,111 @@ static void del_vq(struct virtio_pci_vq_info *info) > vring_del_virtqueue(vq); > } > > +static int virtio_pci_find_shm_cap(struct pci_dev *dev, > + u8 required_id, > + u8 *bar, u64 *offset, u64 *len) > +{ > + int pos; > + > + for (pos = pci_find_capability(dev, PCI_CAP_ID_VNDR); > + pos > 0; > + pos = pci_find_next_capability(dev, pos, PCI_CAP_ID_VNDR)) { > + u8 type, cap_len, id; > + u32 tmp32; > + u64 res_offset, res_length; > + > + pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap, > + cfg_type), > + &type); > + if (type != VIRTIO_PCI_CAP_SHARED_MEMORY_CFG) > + continue; > + > + pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap, > + cap_len), > + &cap_len); > + if (cap_len != sizeof(struct virtio_pci_cap64)) { > + printk(KERN_ERR "%s: shm cap with bad size offset: %d size: %d\n", > + __func__, pos, cap_len); > + continue; > + } > + > + pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap, > + id), > + &id); > + if (id != required_id) > + continue; > + > + /* Type, and ID match, looks good */ > + pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap, > + bar), > + bar); > + > + /* Read the lower 32bit of length and offset */ > + pci_read_config_dword(dev, pos + offsetof(struct virtio_pci_cap, offset), > + &tmp32); > + res_offset = tmp32; > + pci_read_config_dword(dev, pos + offsetof(struct virtio_pci_cap, length), > + &tmp32); > + res_length = tmp32; > + > + /* and now the top half */ > + pci_read_config_dword(dev, > + pos + offsetof(struct virtio_pci_cap64, > + offset_hi), > + &tmp32); > + res_offset |= ((u64)tmp32) << 32; > + pci_read_config_dword(dev, > + pos + offsetof(struct virtio_pci_cap64, > + length_hi), > + &tmp32); > + res_length |= ((u64)tmp32) << 32; > + > + *offset = res_offset; > + *len = res_length; > + > + return pos; > + } > + return 0; > +} > + > +static bool vp_get_shm_region(struct virtio_device *vdev, > + struct virtio_shm_region *region, u8 id) > +{ > + struct virtio_pci_device *vp_dev = to_vp_device(vdev); > + struct pci_dev *pci_dev = vp_dev->pci_dev; > + u8 bar; > + u64 offset, len; > + phys_addr_t phys_addr; > + size_t bar_len; > + int ret; > + > + if (!virtio_pci_find_shm_cap(pci_dev, id, &bar, &offset, &len)) { > + return false; > + } > + > + ret = pci_request_region(pci_dev, bar, "virtio-pci-shm"); > + if (ret < 0) { > + dev_err(&pci_dev->dev, "%s: failed to request BAR\n", > + __func__); > + return false; > + } > + > + phys_addr = pci_resource_start(pci_dev, bar); > + bar_len = pci_resource_len(pci_dev, bar); > + > + if (offset + len > bar_len) { > + dev_err(&pci_dev->dev, > + "%s: bar shorter than cap offset+len\n", > + __func__); > + return false; > + } > + Something wrong with indentation here. Also as long as you are validating things, it's worth checking offset + len does not overflow. > + region->len = len; > + region->addr = (u64) phys_addr + offset; > + > + return true; > +} > + > static const struct virtio_config_ops virtio_pci_config_nodev_ops = { > .get = NULL, > .set = NULL, > @@ -457,6 +562,7 @@ static const struct virtio_config_ops virtio_pci_config_nodev_ops = { > .bus_name = vp_bus_name, > .set_vq_affinity = vp_set_vq_affinity, > .get_vq_affinity = vp_get_vq_affinity, > + .get_shm_region = vp_get_shm_region, > }; > > static const struct virtio_config_ops virtio_pci_config_ops = { > @@ -473,6 +579,7 @@ static const struct virtio_config_ops virtio_pci_config_ops = { > .bus_name = vp_bus_name, > .set_vq_affinity = vp_set_vq_affinity, > .get_vq_affinity = vp_get_vq_affinity, > + .get_shm_region = vp_get_shm_region, > }; > > /** > diff --git a/include/uapi/linux/virtio_pci.h b/include/uapi/linux/virtio_pci.h > index 90007a1abcab..fe9f43680a1d 100644 > --- a/include/uapi/linux/virtio_pci.h > +++ b/include/uapi/linux/virtio_pci.h > @@ -113,6 +113,8 @@ > #define VIRTIO_PCI_CAP_DEVICE_CFG 4 > /* PCI configuration access */ > #define VIRTIO_PCI_CAP_PCI_CFG 5 > +/* Additional shared memory capability */ > +#define VIRTIO_PCI_CAP_SHARED_MEMORY_CFG 8 > > /* This is the PCI capability header: */ > struct virtio_pci_cap { > @@ -121,11 +123,18 @@ struct virtio_pci_cap { > __u8 cap_len; /* Generic PCI field: capability length */ > __u8 cfg_type; /* Identifies the structure. */ > __u8 bar; /* Where to find it. */ > - __u8 padding[3]; /* Pad to full dword. */ > + __u8 id; /* Multiple capabilities of the same type */ > + __u8 padding[2]; /* Pad to full dword. */ > __le32 offset; /* Offset within bar. */ > __le32 length; /* Length of the structure, in bytes. */ > }; > > +struct virtio_pci_cap64 { > + struct virtio_pci_cap cap; > + __le32 offset_hi; /* Most sig 32 bits of offset */ > + __le32 length_hi; /* Most sig 32 bits of length */ > +}; > + > struct virtio_pci_notify_cap { > struct virtio_pci_cap cap; > __le32 notify_off_multiplier; /* Multiplier for queue_notify_off. */ > -- > 2.20.1