[Bug 201753] AMD-Vi: Unable to write to IOMMU perf counter

bugzilla-daemon
2021-03-19T09:57:14Z

--- Comment #30 from Felice Tufo (info@felicetufo.com) ---
Hello, a little update to my previous message: same machine, same kernel, but
this time the patch works. So it seems that also on the same HW the timings are
not so predictable...

[ 1.844903] pci 0000:00:00.2: AMD-Vi: IOMMU performance counters supported
[ 1.845157] pci 0000:00:00.2: can't derive routing for PCI INT A
[ 1.845160] pci 0000:00:00.2: PCI INT A: not connected
[ 1.845213] pci 0000:00:01.0: Adding to iommu group 0
[ 1.845240] pci 0000:00:01.3: Adding to iommu group 1
[ 1.845267] pci 0000:00:02.0: Adding to iommu group 2
[ 1.845284] pci 0000:00:02.1: Adding to iommu group 3
[ 1.845301] pci 0000:00:02.2: Adding to iommu group 4
[ 1.845318] pci 0000:00:02.4: Adding to iommu group 5
[ 1.845349] pci 0000:00:08.0: Adding to iommu group 6
[ 1.845368] pci 0000:00:08.1: Adding to iommu group 6
[ 1.845394] pci 0000:00:14.0: Adding to iommu group 7
[ 1.845411] pci 0000:00:14.3: Adding to iommu group 7
[ 1.845469] pci 0000:00:18.0: Adding to iommu group 8
[ 1.845484] pci 0000:00:18.1: Adding to iommu group 8
[ 1.845500] pci 0000:00:18.2: Adding to iommu group 8
[ 1.845515] pci 0000:00:18.3: Adding to iommu group 8
[ 1.845530] pci 0000:00:18.4: Adding to iommu group 8
[ 1.845545] pci 0000:00:18.5: Adding to iommu group 8
[ 1.845559] pci 0000:00:18.6: Adding to iommu group 8
[ 1.845574] pci 0000:00:18.7: Adding to iommu group 8
[ 1.845592] pci 0000:01:00.0: Adding to iommu group 9
[ 1.845611] pci 0000:02:00.0: Adding to iommu group 10
[ 1.845629] pci 0000:03:00.0: Adding to iommu group 11
[ 1.845646] pci 0000:04:00.0: Adding to iommu group 12
[ 1.845665] pci 0000:05:00.0: Adding to iommu group 6
[ 1.845674] pci 0000:05:00.1: Adding to iommu group 6
[ 1.845683] pci 0000:05:00.2: Adding to iommu group 6
[ 1.845691] pci 0000:05:00.3: Adding to iommu group 6
[ 1.845699] pci 0000:05:00.4: Adding to iommu group 6
[ 1.845706] pci 0000:05:00.5: Adding to iommu group 6
[ 1.845714] pci 0000:05:00.6: Adding to iommu group 6
[ 1.848251] pci 0000:00:00.2: AMD-Vi: Found IOMMU cap 0x40
[ 1.848257] pci 0000:00:00.2: AMD-Vi: Extended features
(0x206d73ef22254ade):
[ 1.848258] PPR X2APIC NX GT IA GA PC GA_vAPIC
[ 1.848263] AMD-Vi: Interrupt remapping enabled
[ 1.848264] AMD-Vi: Virtual APIC enabled
[ 1.848264] AMD-Vi: X2APIC enabled
[ 1.848490] AMD-Vi: Lazy IO/TLB flushing enabled