git: 808ae4e29b6b - main - LinuxKPI: Add pcie_capability_clear_and_set_word() function

The branch main has been updated by wulf:

URL: https://cgit.FreeBSD.org/src/commit/?id=808ae4e29b6b9c9acc7eab013c5045370df8182a

commit 808ae4e29b6b9c9acc7eab013c5045370df8182a
Author:     Vladimir Kondratyev <wulf@FreeBSD.org>
AuthorDate: 2023-12-24 08:20:00 +0000
Commit:     Vladimir Kondratyev <wulf@FreeBSD.org>
CommitDate: 2023-12-24 08:20:00 +0000

    LinuxKPI: Add pcie_capability_clear_and_set_word() function
    
    It does a Read-Modify-Write operation using clear and set bitmasks on
    PCI Express Capability Register at pos. As certain PCI Express
    Capability Registers are accessed concurrently in RMW fashion, hence
    require locking which is handled transparently to the caller.
    
    Sponsored by:   Serenity CyberSecurity, LLC
    Reviewed by:    manu, bz
    MFC after:      1 week
    MFC TODO:       Move pcie_cap_lock to bottom to preserve KBI compatibility
    Differential Revision:  https://reviews.freebsd.org/D42821
---
 sys/compat/linuxkpi/common/include/linux/pci.h | 36 ++++++++++++++------------
 sys/compat/linuxkpi/common/src/linux_pci.c     |  3 +++
 2 files changed, 23 insertions(+), 16 deletions(-)

diff --git a/sys/compat/linuxkpi/common/include/linux/pci.h b/sys/compat/linuxkpi/common/include/linux/pci.h
index aa99b050ffd9..9c7e39bf4a42 100644
--- a/sys/compat/linuxkpi/common/include/linux/pci.h
+++ b/sys/compat/linuxkpi/common/include/linux/pci.h
@@ -347,6 +347,7 @@ struct pci_dev {
 	size_t			romlen;
 	struct msi_desc		**msi_desc;
 	char			*path_name;
+	spinlock_t		pcie_cap_lock;
 
 	TAILQ_HEAD(, pci_mmio_region)	mmio;
 };
@@ -1012,35 +1013,38 @@ pcie_capability_write_word(struct pci_dev *dev, int pos, u16 val)
 }
 
 static inline int
-pcie_capability_set_word(struct pci_dev *dev, int pos, uint16_t val)
+pcie_capability_clear_and_set_word(struct pci_dev *dev, int pos,
+    uint16_t clear, uint16_t set)
 {
 	int error;
 	uint16_t v;
 
+	if (pos == PCI_EXP_LNKCTL || pos == PCI_EXP_RTCTL)
+		spin_lock(&dev->pcie_cap_lock);
+
 	error = pcie_capability_read_word(dev, pos, &v);
-	if (error != 0)
-		return (error);
+	if (error == 0) {
+		v &= ~clear;
+		v |= set;
+		error = pcie_capability_write_word(dev, pos, v);
+	}
 
-	v |= val;
+	if (pos == PCI_EXP_LNKCTL || pos == PCI_EXP_RTCTL)
+		spin_unlock(&dev->pcie_cap_lock);
 
-	error = pcie_capability_write_word(dev, pos, v);
 	return (error);
 }
 
 static inline int
-pcie_capability_clear_word(struct pci_dev *dev, int pos, uint16_t val)
+pcie_capability_set_word(struct pci_dev *dev, int pos, uint16_t val)
 {
-	int error;
-	uint16_t v;
-
-	error = pcie_capability_read_word(dev, pos, &v);
-	if (error != 0)
-		return (error);
-
-	v &= ~val;
+	return (pcie_capability_clear_and_set_word(dev, pos, 0, val));
+}
 
-	error = pcie_capability_write_word(dev, pos, v);
-	return (error);
+static inline int
+pcie_capability_clear_word(struct pci_dev *dev, int pos, uint16_t val)
+{
+	return (pcie_capability_clear_and_set_word(dev, pos, val, 0));
 }
 
 static inline int pcie_get_minimum_link(struct pci_dev *dev,
diff --git a/sys/compat/linuxkpi/common/src/linux_pci.c b/sys/compat/linuxkpi/common/src/linux_pci.c
index 4cd28fac15d3..825ebe319b1a 100644
--- a/sys/compat/linuxkpi/common/src/linux_pci.c
+++ b/sys/compat/linuxkpi/common/src/linux_pci.c
@@ -525,6 +525,7 @@ linux_pci_attach_device(device_t dev, struct pci_driver *pdrv,
 		goto out_dma_init;
 
 	TAILQ_INIT(&pdev->mmio);
+	spin_lock_init(&pdev->pcie_cap_lock);
 
 	spin_lock(&pci_lock);
 	list_add(&pdev->links, &pci_devices);
@@ -539,6 +540,7 @@ linux_pci_attach_device(device_t dev, struct pci_driver *pdrv,
 
 out_probe:
 	free(pdev->bus, M_DEVBUF);
+	spin_lock_destroy(&pdev->pcie_cap_lock);
 	linux_pdev_dma_uninit(pdev);
 out_dma_init:
 	spin_lock(&pci_lock);
@@ -579,6 +581,7 @@ linux_pci_detach_device(struct pci_dev *pdev)
 	spin_lock(&pci_lock);
 	list_del(&pdev->links);
 	spin_unlock(&pci_lock);
+	spin_lock_destroy(&pdev->pcie_cap_lock);
 	put_device(&pdev->dev);
 
 	return (0);