[bug report] iommu/vt-d: Fix kdump kernels boot failure with scalable mode

[Dan Carpenter <dan.carpenter@oracle.com>]

Hello Lu Baolu,

The patch 0c5f6c0d8201: "iommu/vt-d: Fix kdump kernels boot failure
with scalable mode" from Aug 23, 2022, leads to the following Smatch
static checker warning:

drivers/iommu/intel/iommu.c:224 set_context_copied() warn: set_bit() takes a bit number
drivers/iommu/intel/iommu.c:230 clear_context_copied() warn: clear_bit() takes a bit number

drivers/iommu/intel/iommu.c
    221 static inline void
    222 set_context_copied(struct intel_iommu *iommu, u8 bus, u8 devfn)
    223 {
--> 224         set_bit(((long)bus << 8) | devfn, iommu->copied_tables);
    225 }

This is trying to set a mask but it will instead corrupt a bit way out
in the middle of your memory.  The set_bit function will only set one
bit at a time.  If we want to set bit zero:

	set_bit(0, iommu->copied_tables);

Or if we have a whole page full of bits then we could set the last one:

	set_bit(32767, page);

regards,
dan carpenter