linux-kernel - [34-longterm 179/209] x86, vt-d: Handle previous faults after enabling fault handling

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Message-Id: <1302803767-9715-66-git-send-email-paul.gortmaker@windriver.com>
Date:	Thu, 14 Apr 2011 13:55:37 -0400
From:	Paul Gortmaker <paul.gortmaker@...driver.com>
To:	stable@...nel.org, linux-kernel@...r.kernel.org
Cc:	stable-review@...nel.org,
	Suresh Siddha <suresh.b.siddha@...el.com>,
	"H. Peter Anvin" <hpa@...ux.intel.com>,
	Paul Gortmaker <paul.gortmaker@...driver.com>
Subject: [34-longterm 179/209] x86, vt-d: Handle previous faults after enabling fault handling

From: Suresh Siddha <suresh.b.siddha@...el.com>

  =====================================================================
  | This is a commit scheduled for the next v2.6.34 longterm release. |
  | If you see a problem with using this for longterm, please comment.|
  =====================================================================

commit 7f99d946e71e71d484b7543b49e990508e70d0c0 upstream.

Fault handling is getting enabled after enabling the interrupt-remapping (as
the success of interrupt-remapping can affect the apic mode and hence the
fault handling mode).

Hence there can potentially be some faults between the window of enabling
interrupt-remapping in the vt-d and the fault-handling of the vt-d units.

Handle any previous faults after enabling the vt-d fault handling.

For v2.6.38 cleanup, need to check if we can remove the dmar_fault() in the
enable_intr_remapping() and see if we can enable fault handling along with
enabling intr-remapping.

Signed-off-by: Suresh Siddha <suresh.b.siddha@...el.com>
LKML-Reference: <20101201062244.630417138@...el.com>
Acked-by: Chris Wright <chrisw@...s-sol.org>
Signed-off-by: H. Peter Anvin <hpa@...ux.intel.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@...driver.com>
---
 drivers/pci/dmar.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/drivers/pci/dmar.c b/drivers/pci/dmar.c
index 33ead97..0afcc4e 100644
--- a/drivers/pci/dmar.c
+++ b/drivers/pci/dmar.c
@@ -1424,6 +1424,11 @@ int __init enable_drhd_fault_handling(void)
 			       (unsigned long long)drhd->reg_base_addr, ret);
 			return -1;
 		}
+
+		/*
+		 * Clear any previous faults.
+		 */
+		dmar_fault(iommu->irq, iommu);
 	}

 	return 0;
-- 
1.7.4.4

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