[PATCH v4] PCI: vmd: Make vmd_dev::cfg_lock a raw_spinlock_t.

[Sebastian Andrzej Siewior <bigeasy@linutronix.de>]

From: Ryo Takakura <ryotkkr98@gmail.com>

The access to the PCI config space via pci_ops::read and pci_ops::write
is a low-level hardware access. The functions can be accessed with
disabled interrupts even on PREEMPT_RT. The pci_lock has been made a
raw_spinlock_t for this purpose. A spinlock_t becomes a sleeping lock on
PREEMPT_RT can not be acquired with disabled interrupts.
The vmd_dev::cfg_lock is accessed in the same context as the pci_lock.

Make vmd_dev::cfg_lock a raw_spinlock_t.

[bigeasy: Reword commit message.]

Signed-off-by: Ryo Takakura <ryotkkr98@gmail.com>
Tested-by: Luis Claudio R. Goncalves <lgoncalv@redhat.com>
Acked-by: Luis Claudio R. Goncalves <lgoncalv@redhat.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
Changes since v3 https://lore.kernel.org/all/20241219014549.24427-1-ryotkkr98@gmail.com/
- Repost with updated changelog.

Changes since v2 https://lore.kernel.org/lkml/20241218115951.83062-1-ryotkkr98@gmail.com/
- In case if CONFIG_PCI_LOCKLESS_CONFIG is set, vmd_pci_read/write()
  still neeed cfg_lock for their serialization. So instead of removing
  it, convert it to raw spinlock.

v1: https://lore.kernel.org/lkml/20241215141321.383144-1-ryotkkr98@gmail.com/

 drivers/pci/controller/vmd.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
index 9d9596947350f..94ceec50a2b94 100644
--- a/drivers/pci/controller/vmd.c
+++ b/drivers/pci/controller/vmd.c
@@ -125,7 +125,7 @@ struct vmd_irq_list {
 struct vmd_dev {
 	struct pci_dev		*dev;
 
-	spinlock_t		cfg_lock;
+	raw_spinlock_t		cfg_lock;
 	void __iomem		*cfgbar;
 
 	int msix_count;
@@ -391,7 +391,7 @@ static int vmd_pci_read(struct pci_bus *bus, unsigned int devfn, int reg,
 	if (!addr)
 		return -EFAULT;
 
-	spin_lock_irqsave(&vmd->cfg_lock, flags);
+	raw_spin_lock_irqsave(&vmd->cfg_lock, flags);
 	switch (len) {
 	case 1:
 		*value = readb(addr);
@@ -406,7 +406,7 @@ static int vmd_pci_read(struct pci_bus *bus, unsigned int devfn, int reg,
 		ret = -EINVAL;
 		break;
 	}
-	spin_unlock_irqrestore(&vmd->cfg_lock, flags);
+	raw_spin_unlock_irqrestore(&vmd->cfg_lock, flags);
 	return ret;
 }
 
@@ -426,7 +426,7 @@ static int vmd_pci_write(struct pci_bus *bus, unsigned int devfn, int reg,
 	if (!addr)
 		return -EFAULT;
 
-	spin_lock_irqsave(&vmd->cfg_lock, flags);
+	raw_spin_lock_irqsave(&vmd->cfg_lock, flags);
 	switch (len) {
 	case 1:
 		writeb(value, addr);
@@ -444,7 +444,7 @@ static int vmd_pci_write(struct pci_bus *bus, unsigned int devfn, int reg,
 		ret = -EINVAL;
 		break;
 	}
-	spin_unlock_irqrestore(&vmd->cfg_lock, flags);
+	raw_spin_unlock_irqrestore(&vmd->cfg_lock, flags);
 	return ret;
 }
 
@@ -1009,7 +1009,7 @@ static int vmd_probe(struct pci_dev *dev, const struct pci_device_id *id)
 	if (features & VMD_FEAT_OFFSET_FIRST_VECTOR)
 		vmd->first_vec = 1;
 
-	spin_lock_init(&vmd->cfg_lock);
+	raw_spin_lock_init(&vmd->cfg_lock);
 	pci_set_drvdata(dev, vmd);
 	err = vmd_enable_domain(vmd, features);
 	if (err)
-- 
2.47.2