PCI: vmd: Make vmd_dev::cfg_lock a raw_spinlock_t type

JIRA: https://issues.redhat.com/browse/RHEL-83150
Upstream Status: 18056a4

commit 18056a4
Author: Ryo Takakura <ryotkkr98@gmail.com>
Date:   Tue Feb 18 09:08:30 2025 +0100

    PCI: vmd: Make vmd_dev::cfg_lock a raw_spinlock_t type

    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 is a raw_spinlock_t for this
    purpose.

    A spinlock_t becomes a sleeping lock on PREEMPT_RT, so it cannot 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 type so it can be used with
    interrupts disabled.

    This was reported as:

      BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48
      Call Trace:
       rt_spin_lock+0x4e/0x130
       vmd_pci_read+0x8d/0x100 [vmd]
       pci_user_read_config_byte+0x6f/0xe0
       pci_read_config+0xfe/0x290
       sysfs_kf_bin_read+0x68/0x90

    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>
    [bigeasy: reword commit message]
    Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
    Tested-off-by: Luis Claudio R. Goncalves <lgoncalv@redhat.com>
    Link: https://lore.kernel.org/r/20250218080830.ufw3IgyX@linutronix.de
    [kwilczynski: commit log]
    Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
    [bhelgaas: add back report info from
    https://lore.kernel.org/lkml/20241218115951.83062-1-ryotkkr98@gmail.com/]
    Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

Signed-off-by: Myron Stowe <mstowe@redhat.com>

Author: Myron Stowe

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)