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>

diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
index 9d9596947350f5e7a31fa9f8db87147651d37344..94ceec50a2b94cea3bd189f69a587ed2a4527308 100644 (file)
--- 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)