Messages in this thread Patch in this message | | | From | Jean-Philippe Brucker <> | Subject | [PATCH] x86/dma: Tear down DMA ops on driver unbind | Date | Wed, 14 Apr 2021 10:26:34 +0200 |
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Since commit 08a27c1c3ecf ("iommu: Add support to change default domain of an iommu group") a user can switch a device between IOMMU and direct DMA through sysfs. This doesn't work for AMD IOMMU at the moment because dev->dma_ops is not cleared when switching from a DMA to an identity IOMMU domain. The DMA layer thus attempts to use the dma-iommu ops on an identity domain, causing an oops:
# echo 0000:00:05.0 > /sys/sys/bus/pci/drivers/e1000e/unbind # echo identity > /sys/bus/pci/devices/0000:00:05.0/iommu_group/type # echo 0000:00:05.0 > /sys/sys/bus/pci/drivers/e1000e/bind ... [ 190.017587] BUG: kernel NULL pointer dereference, address: 0000000000000028 ... [ 190.027375] Call Trace: [ 190.027561] iommu_dma_alloc+0xd0/0x100 [ 190.027840] e1000e_setup_tx_resources+0x56/0x90 [ 190.028173] e1000e_open+0x75/0x5b0
Implement arch_teardown_dma_ops() on x86 to clear the device's dma_ops pointer during driver unbind.
Fixes: 08a27c1c3ecf ("iommu: Add support to change default domain of an iommu group") Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org> --- arch/x86/Kconfig | 1 + arch/x86/kernel/pci-dma.c | 7 +++++++ 2 files changed, 8 insertions(+)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 2792879d398e..2c90f8de3e20 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -85,6 +85,7 @@ config X86 select ARCH_HAS_STRICT_MODULE_RWX select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE select ARCH_HAS_SYSCALL_WRAPPER + select ARCH_HAS_TEARDOWN_DMA_OPS if IOMMU_DMA select ARCH_HAS_UBSAN_SANITIZE_ALL select ARCH_HAS_DEBUG_WX select ARCH_HAVE_NMI_SAFE_CMPXCHG diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c index de234e7a8962..60a4ec22d849 100644 --- a/arch/x86/kernel/pci-dma.c +++ b/arch/x86/kernel/pci-dma.c @@ -154,3 +154,10 @@ static void via_no_dac(struct pci_dev *dev) DECLARE_PCI_FIXUP_CLASS_FINAL(PCI_VENDOR_ID_VIA, PCI_ANY_ID, PCI_CLASS_BRIDGE_PCI, 8, via_no_dac); #endif + +#ifdef CONFIG_ARCH_HAS_TEARDOWN_DMA_OPS +void arch_teardown_dma_ops(struct device *dev) +{ + set_dma_ops(dev, NULL); +} +#endif -- 2.31.1
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