Linux IOMMU Development
 help / color / mirror / Atom feed
From: Lu Baolu <baolu.lu@linux.intel.com>
To: Joerg Roedel <joro@8bytes.org>, Steve Wahl <steve.wahl@hpe.com>,
	Kevin Tian <kevin.tian@intel.com>
Cc: Dimitri Sivanich <sivanich@hpe.com>,
	Russ Anderson <russ.anderson@hpe.com>,
	Mike Travis <mike.travis@hpe.com>,
	Jerry Snitselaar <jsnitsel@redhat.com>,
	iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org,
	iommu@lists.linux.dev, David Woodhouse <dwmw2@infradead.org>
Subject: [PATCH v2 4/6] iommu/vt-d: Remove unnecessary check in intel_iommu_add()
Date: Sat,  2 Jul 2022 09:56:08 +0800	[thread overview]
Message-ID: <20220702015610.2849494-5-baolu.lu@linux.intel.com> (raw)
In-Reply-To: <20220702015610.2849494-1-baolu.lu@linux.intel.com>

The Intel IOMMU hot-add process starts from dmar_device_hotplug(). It
uses the global dmar_global_lock to synchronize all the hot-add and
hot-remove paths. In the hot-add path, the new IOMMU data structures
are allocated firstly by dmar_parse_one_drhd() and then initialized by
dmar_hp_add_drhd(). All the IOMMU units are allocated and initialized
in the same synchronized path. There is no case where any IOMMU unit
is created and then initialized for multiple times.

This removes the unnecessary check in intel_iommu_add() which is the
last reference place of the global IOMMU array.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
 drivers/iommu/intel/iommu.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 70408c234f5b..d79c48c5fc8c 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -3463,9 +3463,6 @@ static int intel_iommu_add(struct dmar_drhd_unit *dmaru)
 	int sp, ret;
 	struct intel_iommu *iommu = dmaru->iommu;
 
-	if (g_iommus[iommu->seq_id])
-		return 0;
-
 	ret = intel_cap_audit(CAP_AUDIT_HOTPLUG_DMAR, iommu);
 	if (ret)
 		goto out;
-- 
2.25.1

_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu

WARNING: multiple messages have this Message-ID (diff)
From: Lu Baolu <baolu.lu@linux.intel.com>
To: Joerg Roedel <joro@8bytes.org>, Steve Wahl <steve.wahl@hpe.com>,
	Kevin Tian <kevin.tian@intel.com>
Cc: David Woodhouse <dwmw2@infradead.org>,
	Jerry Snitselaar <jsnitsel@redhat.com>,
	Mike Travis <mike.travis@hpe.com>,
	Dimitri Sivanich <sivanich@hpe.com>,
	Russ Anderson <russ.anderson@hpe.com>,
	iommu@lists.linux.dev, iommu@lists.linux-foundation.org,
	linux-kernel@vger.kernel.org, Lu Baolu <baolu.lu@linux.intel.com>
Subject: [PATCH v2 4/6] iommu/vt-d: Remove unnecessary check in intel_iommu_add()
Date: Sat,  2 Jul 2022 09:56:08 +0800	[thread overview]
Message-ID: <20220702015610.2849494-5-baolu.lu@linux.intel.com> (raw)
Message-ID: <20220702015608.1A-eN9vhdzWEHW9TO2snXDT8F8hXlLbWaedFcn3QpyI@z> (raw)
In-Reply-To: <20220702015610.2849494-1-baolu.lu@linux.intel.com>

The Intel IOMMU hot-add process starts from dmar_device_hotplug(). It
uses the global dmar_global_lock to synchronize all the hot-add and
hot-remove paths. In the hot-add path, the new IOMMU data structures
are allocated firstly by dmar_parse_one_drhd() and then initialized by
dmar_hp_add_drhd(). All the IOMMU units are allocated and initialized
in the same synchronized path. There is no case where any IOMMU unit
is created and then initialized for multiple times.

This removes the unnecessary check in intel_iommu_add() which is the
last reference place of the global IOMMU array.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
 drivers/iommu/intel/iommu.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 70408c234f5b..d79c48c5fc8c 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -3463,9 +3463,6 @@ static int intel_iommu_add(struct dmar_drhd_unit *dmaru)
 	int sp, ret;
 	struct intel_iommu *iommu = dmaru->iommu;
 
-	if (g_iommus[iommu->seq_id])
-		return 0;
-
 	ret = intel_cap_audit(CAP_AUDIT_HOTPLUG_DMAR, iommu);
 	if (ret)
 		goto out;
-- 
2.25.1


  parent reply	other threads:[~2022-07-02  2:00 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-07-02  1:56 [PATCH v2 0/6] iommu/vt-d: Reset DMAR_UNITS_SUPPORTED Lu Baolu
2022-07-02  1:56 ` Lu Baolu
2022-07-02  1:56 ` [PATCH v2 1/6] iommu/vt-d: Remove unused domain_get_iommu() Lu Baolu
2022-07-02  1:56   ` Lu Baolu
2022-07-02  1:56 ` [PATCH v2 2/6] iommu/vt-d: Use IDA interface to manage iommu sequence id Lu Baolu
2022-07-02  1:56   ` Lu Baolu
2022-07-07  0:53   ` Tian, Kevin
2022-07-02  1:56 ` [PATCH v2 3/6] iommu/vt-d: Refactor iommu information of each domain Lu Baolu
2022-07-02  1:56   ` Lu Baolu
2022-07-07  1:01   ` Tian, Kevin
2022-07-07  2:22     ` Baolu Lu
2022-07-02  1:56 ` Lu Baolu [this message]
2022-07-02  1:56   ` [PATCH v2 4/6] iommu/vt-d: Remove unnecessary check in intel_iommu_add() Lu Baolu
2022-07-07  1:01   ` Tian, Kevin
2022-07-02  1:56 ` [PATCH v2 5/6] iommu/vt-d: Remove global g_iommus array Lu Baolu
2022-07-02  1:56   ` Lu Baolu
2022-07-02  1:56 ` [PATCH v2 6/6] iommu/vt-d: Make DMAR_UNITS_SUPPORTED default 1024 Lu Baolu
2022-07-02  1:56   ` Lu Baolu

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20220702015610.2849494-5-baolu.lu@linux.intel.com \
    --to=baolu.lu@linux.intel.com \
    --cc=dwmw2@infradead.org \
    --cc=iommu@lists.linux-foundation.org \
    --cc=iommu@lists.linux.dev \
    --cc=joro@8bytes.org \
    --cc=jsnitsel@redhat.com \
    --cc=kevin.tian@intel.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mike.travis@hpe.com \
    --cc=russ.anderson@hpe.com \
    --cc=sivanich@hpe.com \
    --cc=steve.wahl@hpe.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox