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From: sathyanarayanan.kuppuswamy@linux.intel.com
To: bhelgaas@google.com
Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
	ashok.raj@intel.com, keith.busch@intel.com,
	sathyanarayanan.kuppuswamy@linux.intel.com
Subject: [PATCH v6 7/8] PCI/ATS: Disable PF/VF ATS service independently
Date: Fri, 16 Aug 2019 17:10:21 -0700
Message-ID: <cdebd76955086c99a2f5578725c970005b092f6c.1565997310.git.sathyanarayanan.kuppuswamy@linux.intel.com> (raw)
In-Reply-To: <cover.1565997310.git.sathyanarayanan.kuppuswamy@linux.intel.com>

From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>

Currently all VF's needs to be disable their ATS service before
disabling the ATS service in corresponding PF device. But this logic is
incorrect and does not align with the spec. Also it might lead to
some power and performance impact in the system. As per PCIe spec r4.0,
sec 9.3.7.8, ATS Capabilities in VFs and their associated PFs may be
enabled/disabled independently. So remove this dependency logic in
enable/disable code.

Cc: Ashok Raj <ashok.raj@intel.com>
Cc: Keith Busch <keith.busch@intel.com>
Suggested-by: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
---
 drivers/pci/ats.c   | 11 -----------
 include/linux/pci.h |  1 -
 2 files changed, 12 deletions(-)

diff --git a/drivers/pci/ats.c b/drivers/pci/ats.c
index ca633482e565..3a3e81630d7c 100644
--- a/drivers/pci/ats.c
+++ b/drivers/pci/ats.c
@@ -108,8 +108,6 @@ int pci_enable_ats(struct pci_dev *dev, int ps)
 		pdev = pci_physfn(dev);
 		if (pdev->ats_stu != ps)
 			return -EINVAL;
-
-		atomic_inc(&pdev->ats_ref_cnt);  /* count enabled VFs */
 	} else {
 		dev->ats_stu = ps;
 		ctrl |= PCI_ATS_CTRL_STU(dev->ats_stu - PCI_ATS_MIN_STU);
@@ -127,20 +125,11 @@ EXPORT_SYMBOL_GPL(pci_enable_ats);
  */
 void pci_disable_ats(struct pci_dev *dev)
 {
-	struct pci_dev *pdev;
 	u16 ctrl;
 
 	if (WARN_ON(!dev->ats_enabled))
 		return;
 
-	if (atomic_read(&dev->ats_ref_cnt))
-		return;		/* VFs still enabled */
-
-	if (dev->is_virtfn) {
-		pdev = pci_physfn(dev);
-		atomic_dec(&pdev->ats_ref_cnt);
-	}
-
 	pci_read_config_word(dev, dev->ats_cap + PCI_ATS_CTRL, &ctrl);
 	ctrl &= ~PCI_ATS_CTRL_ENABLE;
 	pci_write_config_word(dev, dev->ats_cap + PCI_ATS_CTRL, ctrl);
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 735dc731e0aa..5c72590df0bf 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -452,7 +452,6 @@ struct pci_dev {
 	};
 	u16		ats_cap;	/* ATS Capability offset */
 	u8		ats_stu;	/* ATS Smallest Translation Unit */
-	atomic_t	ats_ref_cnt;	/* Number of VFs with ATS enabled */
 #endif
 #ifdef CONFIG_PCI_PRI
 	u16		pri_cap;	/* PRI Capability offset */
-- 
2.21.0


  parent reply index

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-17  0:10 [PATCH v6 0/8] Fix PF/VF dependency issue sathyanarayanan.kuppuswamy
2019-08-17  0:10 ` [PATCH v6 1/8] PCI/ATS: Fix pci_prg_resp_pasid_required() dependency issues sathyanarayanan.kuppuswamy
2019-08-17  0:10 ` [PATCH v6 2/8] PCI/ATS: Cache PRI capability check result sathyanarayanan.kuppuswamy
2019-08-17  0:10 ` [PATCH v6 3/8] PCI/ATS: Cache PASID " sathyanarayanan.kuppuswamy
2019-08-17  0:10 ` [PATCH v6 4/8] PCI/IOV: Add pci_physfn_reslock/unlock() interfaces sathyanarayanan.kuppuswamy
2019-08-17  0:10 ` [PATCH v6 5/8] PCI/ATS: Add PRI support for PCIe VF devices sathyanarayanan.kuppuswamy
2019-08-17  0:10 ` [PATCH v6 6/8] PCI/ATS: Add PASID " sathyanarayanan.kuppuswamy
2019-08-17  0:10 ` sathyanarayanan.kuppuswamy [this message]
2019-08-17  0:10 ` [PATCH v6 8/8] PCI: Skip Enhanced Allocation (EA) initialization for VF device sathyanarayanan.kuppuswamy

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