x86/mm/pat, drivers/infiniband/ipath: Use arch_phys_wc_add() and require PAT disabled

We are burrying direct access to MTRR code support on
x86 in order to take advantage of PAT. In the future, we
also want to make the default behaviour of ioremap_nocache()
to use strong UC, use of mtrr_add() on those systems
would make write-combining void.

In order to help both enable us to later make strong
UC default and in order to phase out direct MTRR access
code port the driver over to arch_phys_wc_add() and
annotate that the device driver requires systems to
boot with PAT disabled, with the 'nopat' kernel parameter.

This is a workable compromise given that the ipath device
driver powers the old HTX bus cards that only work in
AMD systems, while the newer IB/qib device driver
powers all PCI-e cards. The ipath device driver is
obsolete, hardware is hard to find and because of this
its a reasonable compromise to require users of ipath
to boot with 'nopat'.

Signed-off-by: Luis R. Rodriguez <mcgrof@suse.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Doug Ledford <dledford@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Walls <awalls@md.metrocast.net>
Cc: Antonino Daplas <adaplas@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Hal Rosenstock <hal.rosenstock@gmail.com>
Cc: Jean-Christophe Plagniol-Villard <plagnioj@jcrosoft.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Mike Marciniszyn <mike.marciniszyn@intel.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rickard Strandqvist <rickard_strandqvist@spectrumdigital.se>
Cc: Roger Pau Monné <roger.pau@citrix.com>
Cc: Roland Dreier <roland@purestorage.com>
Cc: Sean Hefty <sean.hefty@intel.com>
Cc: Stefan Bader <stefan.bader@canonical.com>
Cc: Suresh Siddha <sbsiddha@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Ville Syrjälä <syrjala@sci.fi>
Cc: infinipath@intel.com
Cc: jbeulich@suse.com
Cc: konrad.wilk@oracle.com
Cc: linux-rdma@vger.kernel.org
Cc: mchehab@osg.samsung.com
Cc: toshi.kani@hp.com
Link: http://lkml.kernel.org/r/1434053994-2196-4-git-send-email-mcgrof@do-not-panic.com
Link: http://lkml.kernel.org/r/1434356898-25135-5-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/drivers/infiniband/hw/ipath/Kconfig b/drivers/infiniband/hw/ipath/Kconfig
index 1d9bb115cbf60799cd3c705bc0b166bb7640e7d7..8fe54ff00580844479b16345e15e04590d316714 100644 (file)
--- a/drivers/infiniband/hw/ipath/Kconfig
+++ b/drivers/infiniband/hw/ipath/Kconfig
@@ -9,3 +9,6 @@ config INFINIBAND_IPATH
        as IP-over-InfiniBand as well as with userspace applications
        (in conjunction with InfiniBand userspace access).
        For QLogic PCIe QLE based cards, use the QIB driver instead.
+
+       If you have this hardware you will need to boot with PAT disabled
+       on your x86-64 systems, use the nopat kernel parameter.

diff --git a/drivers/infiniband/hw/ipath/ipath_driver.c b/drivers/infiniband/hw/ipath/ipath_driver.c
index bd0caedafe9955c07683b6be7bbb2bdd346a704c..2d7e503d13cb5b9c2855936ce162f41d49ca0ced 100644 (file)
--- a/drivers/infiniband/hw/ipath/ipath_driver.c
+++ b/drivers/infiniband/hw/ipath/ipath_driver.c
@@ -42,6 +42,9 @@
 #include <linux/bitmap.h>
 #include <linux/slab.h>
 #include <linux/module.h>
+#ifdef CONFIG_X86_64
+#include <asm/pat.h>
+#endif
 
 #include "ipath_kernel.h"
 #include "ipath_verbs.h"
@@ -395,6 +398,14 @@ static int ipath_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
        unsigned long long addr;
        u32 bar0 = 0, bar1 = 0;
 
+#ifdef CONFIG_X86_64
+       if (WARN(pat_enabled(),
+                "ipath needs PAT disabled, boot with nopat kernel parameter\n")) {
+               ret = -ENODEV;
+               goto bail;
+       }
+#endif
+
        dd = ipath_alloc_devdata(pdev);
        if (IS_ERR(dd)) {
                ret = PTR_ERR(dd);
@@ -542,6 +553,7 @@ static int ipath_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
        dd->ipath_kregbase = __ioremap(addr, len,
                (_PAGE_NO_CACHE|_PAGE_WRITETHRU));
 #else
+       /* XXX: split this properly to enable on PAT */
        dd->ipath_kregbase = ioremap_nocache(addr, len);
 #endif
 
@@ -587,12 +599,8 @@ static int ipath_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
 
        ret = ipath_enable_wc(dd);
 
-       if (ret) {
-               ipath_dev_err(dd, "Write combining not enabled "
-                             "(err %d): performance may be poor\n",
-                             -ret);
+       if (ret)
                ret = 0;
-       }
 
        ipath_verify_pioperf(dd);
 

diff --git a/drivers/infiniband/hw/ipath/ipath_kernel.h b/drivers/infiniband/hw/ipath/ipath_kernel.h
index e08db7020cd4939809dd456882ff3d4e69480480..f0f9471227793f99f386555100ea0254ff39a1f9 100644 (file)
--- a/drivers/infiniband/hw/ipath/ipath_kernel.h
+++ b/drivers/infiniband/hw/ipath/ipath_kernel.h
@@ -463,9 +463,7 @@ struct ipath_devdata {
        /* offset in HT config space of slave/primary interface block */
        u8 ipath_ht_slave_off;
        /* for write combining settings */
-       unsigned long ipath_wc_cookie;
-       unsigned long ipath_wc_base;
-       unsigned long ipath_wc_len;
+       int wc_cookie;
        /* ref count for each pkey */
        atomic_t ipath_pkeyrefs[4];
        /* shadow copy of struct page *'s for exp tid pages */

diff --git a/drivers/infiniband/hw/ipath/ipath_wc_x86_64.c b/drivers/infiniband/hw/ipath/ipath_wc_x86_64.c
index 4ad0b932df1fab1c1897f144db9ffc8af35c5f73..7b6e4c843e19dce46ff287c416422b60378632ac 100644 (file)
--- a/drivers/infiniband/hw/ipath/ipath_wc_x86_64.c
+++ b/drivers/infiniband/hw/ipath/ipath_wc_x86_64.c
@@ -37,7 +37,6 @@
  */
 
 #include <linux/pci.h>
-#include <asm/mtrr.h>
 #include <asm/processor.h>
 
 #include "ipath_kernel.h"
@@ -122,27 +121,14 @@ int ipath_enable_wc(struct ipath_devdata *dd)
        }
 
        if (!ret) {
-               int cookie;
-               ipath_cdbg(VERBOSE, "Setting mtrr for chip to WC "
-                          "(addr %llx, len=0x%llx)\n",
-                          (unsigned long long) pioaddr,
-                          (unsigned long long) piolen);
-               cookie = mtrr_add(pioaddr, piolen, MTRR_TYPE_WRCOMB, 0);
-               if (cookie < 0) {
-                       {
-                               dev_info(&dd->pcidev->dev,
-                                        "mtrr_add()  WC for PIO bufs "
-                                        "failed (%d)\n",
-                                        cookie);
-                               ret = -EINVAL;
-                       }
-               } else {
-                       ipath_cdbg(VERBOSE, "Set mtrr for chip to WC, "
-                                  "cookie is %d\n", cookie);
-                       dd->ipath_wc_cookie = cookie;
-                       dd->ipath_wc_base = (unsigned long) pioaddr;
-                       dd->ipath_wc_len = (unsigned long) piolen;
-               }
+               dd->wc_cookie = arch_phys_wc_add(pioaddr, piolen);
+               if (dd->wc_cookie < 0) {
+                       ipath_dev_err(dd, "Seting mtrr failed on PIO buffers\n");
+                       ret = -ENODEV;
+               } else if (dd->wc_cookie == 0)
+                       ipath_cdbg(VERBOSE, "Set mtrr for chip to WC not needed\n");
+               else
+                       ipath_cdbg(VERBOSE, "Set mtrr for chip to WC\n");
        }
 
        return ret;
@@ -154,16 +140,5 @@ int ipath_enable_wc(struct ipath_devdata *dd)
  */
 void ipath_disable_wc(struct ipath_devdata *dd)
 {
-       if (dd->ipath_wc_cookie) {
-               int r;
-               ipath_cdbg(VERBOSE, "undoing WCCOMB on pio buffers\n");
-               r = mtrr_del(dd->ipath_wc_cookie, dd->ipath_wc_base,
-                            dd->ipath_wc_len);
-               if (r < 0)
-                       dev_info(&dd->pcidev->dev,
-                                "mtrr_del(%lx, %lx, %lx) failed: %d\n",
-                                dd->ipath_wc_cookie, dd->ipath_wc_base,
-                                dd->ipath_wc_len, r);
-               dd->ipath_wc_cookie = 0; /* even on failure */
-       }
+       arch_phys_wc_del(dd->wc_cookie);
 }