From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ozlabs.org (ozlabs.org [103.22.144.67]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 353ED1A060E for ; Wed, 20 May 2015 22:12:45 +1000 (AEST) Message-ID: <1432123964.27443.17.camel@neuling.org> Subject: Re: [PATCH v2] cxl: Export AFU error buffer via sysfs From: Michael Neuling To: Vaibhav Jain Date: Wed, 20 May 2015 22:12:44 +1000 In-Reply-To: <1432119402-10774-1-git-send-email-vaibhav@linux.vnet.ibm.com> References: <1428910011-4242-1-git-send-email-vaibhav@linux.vnet.ibm.com> <1432119402-10774-1-git-send-email-vaibhav@linux.vnet.ibm.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Cc: Michael Ellerman , ian@ozlabs.au.ibm.com, linuxppc-dev@lists.ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wed, 2015-05-20 at 16:26 +0530, Vaibhav Jain wrote: > Export the "AFU Error Buffer" via sysfs attribute (afu_err_buf). AFU > error buffer is used by the AFU to report application specific > errors. The contents of this buffer are AFU specific and are intended to > be interpreted by the application interacting with the afu. >=20 > Testing: > - Build against pseries le/be configs. > - Run testing with a special version of memcpy afu on a 'be' > kernel. >=20 > Change-log: > v1 -> v2 > - Simplified cxl_afu_read_err_buffer to handle unaligned reads > by performing a short read. >=20 > Signed-off-by: Vaibhav Jain > --- > Documentation/ABI/testing/sysfs-class-cxl | 11 ++++++ > drivers/misc/cxl/cxl.h | 7 ++++ > drivers/misc/cxl/pci.c | 60 +++++++++++++++++++++++++= ++++++ > drivers/misc/cxl/sysfs.c | 33 +++++++++++++++++ > 4 files changed, 111 insertions(+) >=20 > diff --git a/Documentation/ABI/testing/sysfs-class-cxl b/Documentation/AB= I/testing/sysfs-class-cxl > index d46bba8..45e9ce3 100644 > --- a/Documentation/ABI/testing/sysfs-class-cxl > +++ b/Documentation/ABI/testing/sysfs-class-cxl > @@ -6,6 +6,17 @@ Example: The real path of the attribute /sys/class/cxl/a= fu0.0s/irqs_max is > =20 > Slave contexts (eg. /sys/class/cxl/afu0.0s): > =20 > +What: /sys/class/cxl//afu_err_buf > +Date: September 2014 > +Contact: linuxppc-dev@lists.ozlabs.org > +Description: read only > + AFU Error Buffer contents. The contents of this file are > + application specific and depends on the AFU being used. > + Applications interacting with the AFU can use this attribute > + to know about the current error condition and take appropriate > + action like logging the event etc. > + > + > What: /sys/class/cxl//irqs_max > Date: September 2014 > Contact: linuxppc-dev@lists.ozlabs.org > diff --git a/drivers/misc/cxl/cxl.h b/drivers/misc/cxl/cxl.h > index a1cee47..789f077 100644 > --- a/drivers/misc/cxl/cxl.h > +++ b/drivers/misc/cxl/cxl.h > @@ -362,6 +362,10 @@ struct cxl_afu { > struct mutex spa_mutex; > spinlock_t afu_cntl_lock; > =20 > + /* AFU error buffer fields and bin attribute for sysfs */ > + u64 eb_len, eb_offset; > + struct bin_attribute attr_eb; > + > /* > * Only the first part of the SPA is used for the process element > * linked list. The only other part that software needs to worry about > @@ -563,6 +567,9 @@ static inline void __iomem *_cxl_p2n_addr(struct cxl_= afu *afu, cxl_p2n_reg_t reg > u16 cxl_afu_cr_read16(struct cxl_afu *afu, int cr, u64 off); > u8 cxl_afu_cr_read8(struct cxl_afu *afu, int cr, u64 off); > =20 > +ssize_t cxl_afu_read_err_buffer(struct cxl_afu *afu, char *buf, > + loff_t off, size_t count); > + > =20 > struct cxl_calls { > void (*cxl_slbia)(struct mm_struct *mm); > diff --git a/drivers/misc/cxl/pci.c b/drivers/misc/cxl/pci.c > index 1ef0164..162a8fc 100644 > --- a/drivers/misc/cxl/pci.c > +++ b/drivers/misc/cxl/pci.c > @@ -593,6 +593,22 @@ static int cxl_read_afu_descriptor(struct cxl_afu *a= fu) > afu->crs_len =3D AFUD_CR_LEN(val) * 256; > afu->crs_offset =3D AFUD_READ_CR_OFF(afu); > =20 > + > + /* eb_len is in multiple of 4K */ > + afu->eb_len =3D AFUD_EB_LEN(AFUD_READ_EB(afu)) * 4096; > + afu->eb_offset =3D AFUD_READ_EB_OFF(afu); > + > + /* eb_off is 4K aligned so lower 12 bits are always zero */ > + if (EXTRACT_PPC_BITS(afu->eb_offset, 0, 11) !=3D 0) { > + dev_warn(&afu->dev, > + "Invalid AFU error buffer offset %Lx\n", > + afu->eb_offset); > + dev_info(&afu->dev, > + "Ignoring AFU error buffer in the descriptor\n"); > + /* indicate that no afu buffer exists */ > + afu->eb_len =3D 0; > + } > + > return 0; > } > =20 > @@ -672,6 +688,50 @@ static int sanitise_afu_regs(struct cxl_afu *afu) > return 0; > } > =20 > +/* > + * afu_eb_read: > + * Called from sysfs and reads the afu error info buffer. The h/w only s= upports > + * 4/8 bytes aligned access. So most of the code tries to get around thi= s by > + * reading full 8 bytes aligned chunks, copying it to a temp buffer and = dropping > + * unneeded bytes at the beginning & the end of the requested region. > + */ > +ssize_t cxl_afu_read_err_buffer(struct cxl_afu *afu, char *buf, > + loff_t off, size_t count) > +{ > + u8 tbuff[8]; > + const void __iomem *ebuf =3D afu->afu_desc_mmio + afu->eb_offset; > + > + count =3D min((size_t)(afu->eb_len - off), count); > + > + if (unlikely(count <=3D 0)) { > + /* handle case where no ebuf exists or offset out of bound */ > + count =3D 0; > + > + } else if ((count >=3D 8) && IS_ALIGNED(off, 8)) { > + /* read all the intermediate aligned words */ > + > + count =3D round_down(off + count, 8) - off; > + _memcpy_fromio(buf, > + ebuf + off, count); > + > + } else if (!IS_ALIGNED(off, 8)) { > + /* handle unaligned access at the beginning */ > + _memcpy_fromio(tbuff, ebuf + round_down(off, 8), 8); > + > + count =3D min((size_t)(ALIGN(off, 8) - off), count); > + memcpy(buf, tbuff + (off & 0x7), count); > + > + } else { > + /* offset is aligned but count < 8 */ > + _memcpy_fromio(tbuff, ebuf + round_down(off + count, 8), 8); > + > + count =3D (off + count) - round_down(off + count, 8); > + memcpy(buf, tbuff, count); > + } I still think this is too complex. How about something like this where we always use a copy buffer (completely untested): copy_size_max =3D PAGESIZE; =20 ebuf_start =3D round_down(off, 8); ebuf_length =3D min(count + 16, copy_size_max); // copy extra for a= lignment at start and end count =3D min(count, copy_size_max); // Adjust for max copy length count =3D count - (off & 7); // Adjust for non aligned offset =20 tbuff =3D __get_free_page(GFP_KERNEL); =20 _memcpy_fromio(tbuff, ebuf_start, ebuf_length); memcpy(buf, tbuff + (off & 0x7), count); // grab what we need =20 free_page(tbuff); =20 return count; =20 Mikey > + > + return count; > +} > + > static int cxl_init_afu(struct cxl *adapter, int slice, struct pci_dev *= dev) > { > struct cxl_afu *afu; > diff --git a/drivers/misc/cxl/sysfs.c b/drivers/misc/cxl/sysfs.c > index d0c38c7..4942d55 100644 > --- a/drivers/misc/cxl/sysfs.c > +++ b/drivers/misc/cxl/sysfs.c > @@ -356,6 +356,16 @@ static ssize_t api_version_compatible_show(struct de= vice *device, > return scnprintf(buf, PAGE_SIZE, "%i\n", CXL_API_VERSION_COMPATIBLE); > } > =20 > +static ssize_t afu_eb_read(struct file *filp, struct kobject *kobj, > + struct bin_attribute *bin_attr, char *buf, > + loff_t off, size_t count) > +{ > + struct cxl_afu *afu =3D to_cxl_afu(container_of(kobj, > + struct device, kobj)); > + > + return cxl_afu_read_err_buffer(afu, buf, off, count); > +} > + > static struct device_attribute afu_attrs[] =3D { > __ATTR_RO(mmio_size), > __ATTR_RO(irqs_min), > @@ -534,6 +544,10 @@ void cxl_sysfs_afu_remove(struct cxl_afu *afu) > struct afu_config_record *cr, *tmp; > int i; > =20 > + /* remove the err buffer bin attribute */ > + if (afu->eb_len) > + device_remove_bin_file(&afu->dev, &afu->attr_eb); > + > for (i =3D 0; i < ARRAY_SIZE(afu_attrs); i++) > device_remove_file(&afu->dev, &afu_attrs[i]); > =20 > @@ -555,6 +569,22 @@ int cxl_sysfs_afu_add(struct cxl_afu *afu) > goto err; > } > =20 > + /* conditionally create the add the binary file for error info buffer *= / > + if (afu->eb_len) { > + afu->attr_eb.attr.name =3D "afu_err_buff"; > + afu->attr_eb.attr.mode =3D S_IRUGO; > + afu->attr_eb.size =3D afu->eb_len; > + afu->attr_eb.read =3D afu_eb_read; > + > + rc =3D device_create_bin_file(&afu->dev, &afu->attr_eb); > + if (rc) { > + dev_err(&afu->dev, > + "Unable to create eb attr for the afu. Err(%d)\n", > + rc); > + goto err; > + } > + } > + > for (i =3D 0; i < afu->crs_num; i++) { > cr =3D cxl_sysfs_afu_new_cr(afu, i); > if (IS_ERR(cr)) { > @@ -570,6 +600,9 @@ err1: > cxl_sysfs_afu_remove(afu); > return rc; > err: > + /* reset the eb_len as we havent created the bin attr */ > + afu->eb_len =3D 0; > + > for (i--; i >=3D 0; i--) > device_remove_file(&afu->dev, &afu_attrs[i]); > return rc;