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[Xen-changelog] [xen staging-4.12] passthrough/vtd: Drop the "workaround_bios_bug" logic entirely



commit 07c181c83e03a860d806305369cd677c24df9b78
Author:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
AuthorDate: Thu Mar 21 19:36:48 2019 +0000
Commit:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Fri Mar 22 12:35:58 2019 +0000

    passthrough/vtd: Drop the "workaround_bios_bug" logic entirely
    
    It turns out that this code was previously dead.
    
    c/s dcf41790 " x86/mmcfg/drhd: Move acpi_mmcfg_init() call before calling
    acpi_parse_dmar()" resulted in PCI segment 0 now having been initialised
    enough for acpi_parse_one_drhd() to not take the
    
      /* Skip checking if segment is not accessible yet. */
    
    path unconditionally.  However, some systems have DMAR tables which list
    devices which are disabled by user choice (in particular, Dell PowerEdge 
R740
    with I/O AT DMA disabled), and turning off all IOMMU functionality in this
    case is entirely unhelpful behaviour.
    
    Leave the warning which identifies the problematic devices, but drop the
    remaining logic.  This leaves the system in better overall state, and 
working
    in the same way that it did in previous releases.
    
    Reported-by: Igor Druzhinin <igor.druzhinin@xxxxxxxxxx>
    Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Reviewed-by: Igor Druzhinin <igor.druzhinin@xxxxxxxxxx>
    Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
    Acked-by: George Dunlap <george.dunlap@xxxxxxxxxx>
    Release-acked-by: Juergen Gross <jgross@xxxxxxxx>
    (cherry picked from commit 74dadb8556c6a0972fa422b5ae346589ace404b6)
---
 docs/misc/xen-command-line.pandoc  |  7 +------
 xen/drivers/passthrough/iommu.c    |  3 ---
 xen/drivers/passthrough/vtd/dmar.c | 29 ++---------------------------
 xen/include/xen/iommu.h            |  3 +--
 4 files changed, 4 insertions(+), 38 deletions(-)

diff --git a/docs/misc/xen-command-line.pandoc 
b/docs/misc/xen-command-line.pandoc
index a03c0b4bdf..2a3e812ceb 100644
--- a/docs/misc/xen-command-line.pandoc
+++ b/docs/misc/xen-command-line.pandoc
@@ -1173,8 +1173,7 @@ detection of systems known to misbehave upon accesses to 
that port.
 ### iommu
     = List of [ <bool>, verbose, debug, force, required,
                 sharept, intremap, intpost,
-                snoop, qinval, igfx, workaround_bios_bug,
-                amd-iommu-perdev-intremap,
+                snoop, qinval, igfx, amd-iommu-perdev-intremap,
                 dom0-{passthrough,strict} ]
 
     All sub-options are boolean in nature.
@@ -1259,10 +1258,6 @@ The following options are specific to Intel VT-d 
hardware:
     similar to Linux's `intel_iommu=igfx_off` option.  If specifying `no-igfx`
     fixes anything, please report the problem.
 
-*   The `workaround_bios_bug` boolean is disabled by default.  It can be used
-    to ignore errors when parsing the ACPI tables, and finding a listed PCI
-    device which doesn't appear to exist in the system.
-
 The following options are specific to AMD-Vi hardware:
 
 *   The `amd-iommu-perdev-intremap` boolean controls whether the interrupt
diff --git a/xen/drivers/passthrough/iommu.c b/xen/drivers/passthrough/iommu.c
index 5ecaa10bb4..117b869b0c 100644
--- a/xen/drivers/passthrough/iommu.c
+++ b/xen/drivers/passthrough/iommu.c
@@ -30,7 +30,6 @@ bool_t __initdata iommu_enable = 1;
 bool_t __read_mostly iommu_enabled;
 bool_t __read_mostly force_iommu;
 bool_t __read_mostly iommu_verbose;
-bool_t __read_mostly iommu_workaround_bios_bug;
 bool_t __read_mostly iommu_igfx = 1;
 bool_t __read_mostly iommu_snoop = 1;
 bool_t __read_mostly iommu_qinval = 1;
@@ -74,8 +73,6 @@ static int __init parse_iommu_param(const char *s)
         else if ( (val = parse_boolean("force", s, ss)) >= 0 ||
                   (val = parse_boolean("required", s, ss)) >= 0 )
             force_iommu = val;
-        else if ( (val = parse_boolean("workaround_bios_bug", s, ss)) >= 0 )
-            iommu_workaround_bios_bug = val;
         else if ( (val = parse_boolean("igfx", s, ss)) >= 0 )
             iommu_igfx = val;
         else if ( (val = parse_boolean("verbose", s, ss)) >= 0 )
diff --git a/xen/drivers/passthrough/vtd/dmar.c 
b/xen/drivers/passthrough/vtd/dmar.c
index 81afa5498e..2372cd2c74 100644
--- a/xen/drivers/passthrough/vtd/dmar.c
+++ b/xen/drivers/passthrough/vtd/dmar.c
@@ -514,7 +514,7 @@ acpi_parse_one_drhd(struct acpi_dmar_header *header)
     else
     {
         u8 b, d, f;
-        unsigned int i = 0, invalid_cnt = 0;
+        unsigned int i = 0;
         union {
             const void *raw;
             const struct acpi_dmar_device_scope *scope;
@@ -536,37 +536,12 @@ acpi_parse_one_drhd(struct acpi_dmar_header *header)
             f = PCI_FUNC(dmaru->scope.devices[i]);
 
             if ( !pci_device_detect(drhd->segment, b, d, f) )
-            {
                 printk(XENLOG_WARNING VTDPREFIX
                        " Non-existent device (%04x:%02x:%02x.%u) in this 
DRHD's scope!\n",
                        drhd->segment, b, d, f);
-                invalid_cnt++;
-            }
         }
 
-        if ( invalid_cnt )
-        {
-            if ( iommu_workaround_bios_bug &&
-                 invalid_cnt == dmaru->scope.devices_cnt )
-            {
-                printk(XENLOG_WARNING VTDPREFIX
-                       "  Workaround BIOS bug: ignoring DRHD (no devices in 
its scope are PCI discoverable)\n");
-
-                scope_devices_free(&dmaru->scope);
-                iommu_free(dmaru);
-                xfree(dmaru);
-            }
-            else
-            {
-                printk(XENLOG_WARNING VTDPREFIX
-                       "  DRHD is invalid (some devices in its scope are not 
PCI discoverable)\n");
-                printk(XENLOG_WARNING VTDPREFIX
-                       "  Try \"iommu=force\" or \"iommu=workaround_bios_bug\" 
if you really want VT-d\n");
-                ret = -EINVAL;
-            }
-        }
-        else
-            acpi_register_drhd_unit(dmaru);
+        acpi_register_drhd_unit(dmaru);
     }
 
 out:
diff --git a/xen/include/xen/iommu.h b/xen/include/xen/iommu.h
index 64a50783cb..62a24d542a 100644
--- a/xen/include/xen/iommu.h
+++ b/xen/include/xen/iommu.h
@@ -53,8 +53,7 @@ static inline bool_t dfn_eq(dfn_t x, dfn_t y)
 }
 
 extern bool_t iommu_enable, iommu_enabled;
-extern bool_t force_iommu, iommu_verbose;
-extern bool_t iommu_workaround_bios_bug, iommu_igfx;
+extern bool_t force_iommu, iommu_verbose, iommu_igfx;
 extern bool_t iommu_snoop, iommu_qinval, iommu_intremap, iommu_intpost;
 extern bool_t iommu_hap_pt_share;
 extern bool_t iommu_debug;
--
generated by git-patchbot for /home/xen/git/xen.git#staging-4.12

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