drivers/iommu/intel/dmar.c:1506 dmar_disable_qi() warn: this loop depends on readl() succeeding

drivers/iommu/intel/dmar.c:1506 dmar_disable_qi() warn: this loop depends on readl() succeeding

[kernel test robot]

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CC: kbuild-all(a)lists.01.org
CC: linux-kernel(a)vger.kernel.org
TO: Joerg Roedel <jroedel@suse.de>
CC: Jerry Snitselaar <jsnitsel@redhat.com>
CC: Lu Baolu <baolu.lu@linux.intel.com>

Hi Joerg,

First bad commit (maybe != root cause):

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   6bff9bb8a292668e7da3e740394b061e5201f683
commit: 672cf6df9b8a3a6d70a6a5c30397f76fa40d3178 iommu/vt-d: Move Intel IOMMU driver into subdirectory
date:   6 months ago
:::::: branch date: 76 minutes ago
:::::: commit date: 6 months ago
config: i386-randconfig-m021-20201213 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-15) 9.3.0

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>

smatch warnings:
drivers/iommu/intel/dmar.c:1506 dmar_disable_qi() warn: this loop depends on readl() succeeding
drivers/iommu/intel/dmar.c:1506 dmar_disable_qi() warn: this loop depends on readl() succeeding
drivers/iommu/intel/dmar.c:1872 dmar_fault() warn: this loop depends on readl() succeeding
drivers/iommu/intel/dmar.c:2023 dmar_detect_dsm() warn: should '1 << func' be a 64 bit type?

vim +1506 drivers/iommu/intel/dmar.c

61a06a16e36d83 drivers/iommu/dmar.c Jacob Pan       2020-05-16  1476  
eba67e5da6e971 drivers/pci/dmar.c   Suresh Siddha   2009-03-16  1477  /*
eba67e5da6e971 drivers/pci/dmar.c   Suresh Siddha   2009-03-16  1478   * Disable Queued Invalidation interface.
eba67e5da6e971 drivers/pci/dmar.c   Suresh Siddha   2009-03-16  1479   */
eba67e5da6e971 drivers/pci/dmar.c   Suresh Siddha   2009-03-16  1480  void dmar_disable_qi(struct intel_iommu *iommu)
eba67e5da6e971 drivers/pci/dmar.c   Suresh Siddha   2009-03-16  1481  {
eba67e5da6e971 drivers/pci/dmar.c   Suresh Siddha   2009-03-16  1482  	unsigned long flags;
eba67e5da6e971 drivers/pci/dmar.c   Suresh Siddha   2009-03-16  1483  	u32 sts;
eba67e5da6e971 drivers/pci/dmar.c   Suresh Siddha   2009-03-16  1484  	cycles_t start_time = get_cycles();
eba67e5da6e971 drivers/pci/dmar.c   Suresh Siddha   2009-03-16  1485  
eba67e5da6e971 drivers/pci/dmar.c   Suresh Siddha   2009-03-16  1486  	if (!ecap_qis(iommu->ecap))
eba67e5da6e971 drivers/pci/dmar.c   Suresh Siddha   2009-03-16  1487  		return;
eba67e5da6e971 drivers/pci/dmar.c   Suresh Siddha   2009-03-16  1488  
1f5b3c3fd2d73d drivers/iommu/dmar.c Thomas Gleixner 2011-07-19  1489  	raw_spin_lock_irqsave(&iommu->register_lock, flags);
eba67e5da6e971 drivers/pci/dmar.c   Suresh Siddha   2009-03-16  1490  
fda3bec12d0979 drivers/iommu/dmar.c CQ Tang         2016-01-13  1491  	sts =  readl(iommu->reg + DMAR_GSTS_REG);
eba67e5da6e971 drivers/pci/dmar.c   Suresh Siddha   2009-03-16  1492  	if (!(sts & DMA_GSTS_QIES))
eba67e5da6e971 drivers/pci/dmar.c   Suresh Siddha   2009-03-16  1493  		goto end;
eba67e5da6e971 drivers/pci/dmar.c   Suresh Siddha   2009-03-16  1494  
eba67e5da6e971 drivers/pci/dmar.c   Suresh Siddha   2009-03-16  1495  	/*
eba67e5da6e971 drivers/pci/dmar.c   Suresh Siddha   2009-03-16  1496  	 * Give a chance to HW to complete the pending invalidation requests.
eba67e5da6e971 drivers/pci/dmar.c   Suresh Siddha   2009-03-16  1497  	 */
eba67e5da6e971 drivers/pci/dmar.c   Suresh Siddha   2009-03-16  1498  	while ((readl(iommu->reg + DMAR_IQT_REG) !=
eba67e5da6e971 drivers/pci/dmar.c   Suresh Siddha   2009-03-16  1499  		readl(iommu->reg + DMAR_IQH_REG)) &&
eba67e5da6e971 drivers/pci/dmar.c   Suresh Siddha   2009-03-16  1500  		(DMAR_OPERATION_TIMEOUT > (get_cycles() - start_time)))
eba67e5da6e971 drivers/pci/dmar.c   Suresh Siddha   2009-03-16  1501  		cpu_relax();
eba67e5da6e971 drivers/pci/dmar.c   Suresh Siddha   2009-03-16  1502  
eba67e5da6e971 drivers/pci/dmar.c   Suresh Siddha   2009-03-16  1503  	iommu->gcmd &= ~DMA_GCMD_QIE;
eba67e5da6e971 drivers/pci/dmar.c   Suresh Siddha   2009-03-16  1504  	writel(iommu->gcmd, iommu->reg + DMAR_GCMD_REG);
eba67e5da6e971 drivers/pci/dmar.c   Suresh Siddha   2009-03-16  1505  
eba67e5da6e971 drivers/pci/dmar.c   Suresh Siddha   2009-03-16 @1506  	IOMMU_WAIT_OP(iommu, DMAR_GSTS_REG, readl,
eba67e5da6e971 drivers/pci/dmar.c   Suresh Siddha   2009-03-16  1507  		      !(sts & DMA_GSTS_QIES), sts);
eba67e5da6e971 drivers/pci/dmar.c   Suresh Siddha   2009-03-16  1508  end:
1f5b3c3fd2d73d drivers/iommu/dmar.c Thomas Gleixner 2011-07-19  1509  	raw_spin_unlock_irqrestore(&iommu->register_lock, flags);
eba67e5da6e971 drivers/pci/dmar.c   Suresh Siddha   2009-03-16  1510  }
eba67e5da6e971 drivers/pci/dmar.c   Suresh Siddha   2009-03-16  1511  

:::::: The code at line 1506 was first introduced by commit
:::::: eba67e5da6e971993b2899d2cdf459ce77d3dbc5 x86, dmar: routines for disabling queued invalidation and intr remapping

:::::: TO: Suresh Siddha <suresh.b.siddha@intel.com>
:::::: CC: H. Peter Anvin <hpa@linux.intel.com>

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org

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