Commit 18056a48 authored Feb 18, 2025 by Ryo Takakura Committed by Bjorn Helgaas Mar 18, 2025

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>

parent 2014c95a

drivers/pci/controller/vmd.c

+6 −6

Original line number	Diff line number	Diff line
		@@ -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)