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[86.153.196.174]) by smtp.gmail.com with ESMTPSA id 132sm2049452wmg.5.2017.05.25.11.16.14 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 25 May 2017 11:16:14 -0700 (PDT) Date: Thu, 25 May 2017 19:13:23 +0100 From: Piotr Gregor To: Bjorn Helgaas Cc: Alex Williamson , "Michael S. Tsirkin" , Greg Kroah-Hartman , Neo Jia , Kirti Wankhede , Vlad Tsyrklevich , Arvind Yadav , Yongji Xie , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org Subject: [PATCH] PCI: Move test of INTx masking to pci_setup_device Message-ID: <20170525181321.GA13617@westernst> MIME-Version: 1.0 Content-Disposition: inline User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The test for INTx masking via config space command performed in pci_intx_mask_supported should be performed before PCI device can be used. This is to avoid reading/writing of PCI_COMMAND_INTX_DISABLE register which may collide with MSI/MSI-X interrupts. This patch simplifies test performed in pci_intx_mask_supported and introduces intx_mask_support field in struct pci_dev to store the result. The test itself is moved to pci_setup_device. The result can be queried at any time later from the pci_dev with static inline bool pci_is_intx_mask_supported(struct pci_dev *pdev) { /* * INTx masking is supported if device passed INTx test * and it's INTx masking feature works properly. */ return (pdev->intx_mask_support && !pdev->broken_intx_masking); } Signed-off-by: Piotr Gregor --- drivers/pci/pci.c | 42 +++++++++++++++++++++++------------------- drivers/pci/probe.c | 3 +++ drivers/uio/uio_pci_generic.c | 2 +- drivers/vfio/pci/vfio_pci.c | 2 +- include/linux/pci.h | 10 ++++++++++ 5 files changed, 38 insertions(+), 21 deletions(-) diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index b01bd5b..bcaab9b 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -3709,42 +3709,46 @@ void pci_intx(struct pci_dev *pdev, int enable) EXPORT_SYMBOL_GPL(pci_intx); /** - * pci_intx_mask_supported - probe for INTx masking support + * pci_intx_mask_supported - probe for INTx masking support in pci_setup_device * @dev: the PCI device to operate on * - * Check if the device dev support INTx masking via the config space - * command word. + * Check if the device dev supports INTx masking via the config space + * command word. Executed when PCI device is setup. Result is saved + * in intx_mask_support field of pci_dev and should be checked + * with pci_is_intx_mask_supported() after PCI device has been setup + * to avoid reading/writing of PCI_COMMAND_INTX_DISABLE register. */ bool pci_intx_mask_supported(struct pci_dev *dev) { - bool mask_supported = false; - u16 orig, new; + u16 orig, toggle, new; + /* + * If device doesn't support this feature though it could pass the test. + */ if (dev->broken_intx_masking) return false; pci_cfg_access_lock(dev); + /* + * Perform the test. + */ pci_read_config_word(dev, PCI_COMMAND, &orig); - pci_write_config_word(dev, PCI_COMMAND, - orig ^ PCI_COMMAND_INTX_DISABLE); + toggle = orig ^ PCI_COMMAND_INTX_DISABLE; + pci_write_config_word(dev, PCI_COMMAND, toggle); pci_read_config_word(dev, PCI_COMMAND, &new); /* - * There's no way to protect against hardware bugs or detect them - * reliably, but as long as we know what the value should be, let's - * go ahead and check it. + * Restore initial state. */ - if ((new ^ orig) & ~PCI_COMMAND_INTX_DISABLE) { - dev_err(&dev->dev, "Command register changed from 0x%x to 0x%x: driver or hardware bug?\n", - orig, new); - } else if ((new ^ orig) & PCI_COMMAND_INTX_DISABLE) { - mask_supported = true; - pci_write_config_word(dev, PCI_COMMAND, orig); - } + pci_write_config_word(dev, PCI_COMMAND, orig); pci_cfg_access_unlock(dev); - return mask_supported; + + if (new == toggle) + return true; + + return false; } EXPORT_SYMBOL_GPL(pci_intx_mask_supported); @@ -3798,7 +3802,7 @@ static bool pci_check_and_set_intx_mask(struct pci_dev *dev, bool mask) * @dev: the PCI device to operate on * * Check if the device dev has its INTx line asserted, mask it and - * return true in that case. False is returned if not interrupt was + * return true in that case. False is returned if no interrupt was * pending. */ bool pci_check_and_mask_intx(struct pci_dev *dev) diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 19c8950..16c60ce 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -1399,6 +1399,9 @@ int pci_setup_device(struct pci_dev *dev) } } + if (pci_intx_mask_supported(dev)) + dev->intx_mask_support = 1; + switch (dev->hdr_type) { /* header type */ case PCI_HEADER_TYPE_NORMAL: /* standard header */ if (class == PCI_CLASS_BRIDGE_PCI) diff --git a/drivers/uio/uio_pci_generic.c b/drivers/uio/uio_pci_generic.c index d0b508b..8cd443c 100644 --- a/drivers/uio/uio_pci_generic.c +++ b/drivers/uio/uio_pci_generic.c @@ -73,7 +73,7 @@ static int probe(struct pci_dev *pdev, return -ENODEV; } - if (!pci_intx_mask_supported(pdev)) { + if (!pci_is_intx_mask_supported(pdev)) { err = -ENODEV; goto err_verify; } diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c index 324c52e..933456e 100644 --- a/drivers/vfio/pci/vfio_pci.c +++ b/drivers/vfio/pci/vfio_pci.c @@ -239,7 +239,7 @@ static int vfio_pci_enable(struct vfio_pci_device *vdev) vdev->nointx = true; pci_intx(pdev, 0); } else - vdev->pci_2_3 = pci_intx_mask_supported(pdev); + vdev->pci_2_3 = pci_is_intx_mask_supported(pdev); } pci_read_config_word(pdev, PCI_COMMAND, &cmd); diff --git a/include/linux/pci.h b/include/linux/pci.h index 33c2b0b..0fbd278 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -367,6 +367,7 @@ struct pci_dev { unsigned int __aer_firmware_first_valid:1; unsigned int __aer_firmware_first:1; unsigned int broken_intx_masking:1; + unsigned int intx_mask_support:1; /* INTx masking is supported */ unsigned int io_window_1k:1; /* Intel P2P bridge 1K I/O windows */ unsigned int irq_managed:1; unsigned int has_secondary_link:1; @@ -1003,6 +1004,15 @@ int __must_check pci_reenable_device(struct pci_dev *); int __must_check pcim_enable_device(struct pci_dev *pdev); void pcim_pin_device(struct pci_dev *pdev); +static inline bool pci_is_intx_mask_supported(struct pci_dev *pdev) +{ + /* + * INTx masking is supported if device passed INTx test and it's INTx + * masking feature works properly. + */ + return (pdev->intx_mask_support && !pdev->broken_intx_masking); +} + static inline int pci_is_enabled(struct pci_dev *pdev) { return (atomic_read(&pdev->enable_cnt) > 0);