Dear Alexander,
Am 01.06.20 um 04:48 schrieb Paul Menzel:
[…]
Am 31.05.20 um 09:22 schrieb Alexander Monakov:
Adding Shuah Khan to Cc: I've noticed you've seen this issue on Ryzen 2400GE;
can you have a look at the patch? Would be nice to know if it fixes the
problem for you too.
On Fri, 29 May 2020, Alexander Monakov wrote:
The driver performs an extra check if the IOMMU's capabilities advertise
presence of performance counters: it verifies that counters are writable
by writing a hard-coded value to a counter and testing that reading that
counter gives back the same value.
Unfortunately it does so quite early, even before pci_enable_device is
called for the IOMMU, i.e. when accessing its MMIO space is not
guaranteed to work. On Ryzen 4500U CPU, this actually breaks the test:
the driver assumes the counters are not writable, and disables the
functionality.
Moving init_iommu_perf_ctr just after iommu_flush_all_caches resolves
the issue. This is the earliest point in amd_iommu_init_pci where the
call succeeds on my laptop.
Signed-off-by: Alexander Monakov <amona...@ispras.ru>
Cc: Joerg Roedel <j...@8bytes.org>
Cc: Suravee Suthikulpanit <suravee.suthikulpa...@amd.com>
Cc: io...@lists.linux-foundation.org
---
PS. I'm seeing another hiccup with IOMMU probing on my system:
pci 0000:00:00.2: can't derive routing for PCI INT A
pci 0000:00:00.2: PCI INT A: not connected
Hopefully I can figure it out, but I'd appreciate hints.
I guess it’s a firmware bug, but I contacted the linux-pci folks [1].
Unfortunately, it’s still present in Linux 5.11.
drivers/iommu/amd_iommu_init.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/iommu/amd_iommu_init.c
b/drivers/iommu/amd_iommu_init.c
index 5b81fd16f5fa..1b7ec6b6a282 100644
--- a/drivers/iommu/amd_iommu_init.c
+++ b/drivers/iommu/amd_iommu_init.c
@@ -1788,8 +1788,6 @@ static int __init iommu_init_pci(struct
amd_iommu *iommu)
if (iommu->cap & (1UL << IOMMU_CAP_NPCACHE))
amd_iommu_np_cache = true;
- init_iommu_perf_ctr(iommu);
-
if (is_rd890_iommu(iommu->dev)) {
int i, j;
@@ -1891,8 +1889,10 @@ static int __init amd_iommu_init_pci(void)
init_device_table_dma();
- for_each_iommu(iommu)
+ for_each_iommu(iommu) {
iommu_flush_all_caches(iommu);
+ init_iommu_perf_ctr(iommu);
+ }
if (!ret)
print_iommu_info();
base-commit: 75caf310d16cc5e2f851c048cd597f5437013368
Thank you very much for fixing this issue, which is almost two years old
for me.
Tested-by: Paul Menzel <pmen...@molgen.mpg.de>
MSI MSI MS-7A37/B350M MORTAR with AMD Ryzen 3 2200G
Link: https://lore.kernel.org/linux-iommu/20180727102710.ga6...@8bytes.org/
Just a small note, that I am applying your patch, but it looks like
there is still some timing issue. At least today, I noticed it during
one boot with Linux 5.11. (Before I never noticed it again in the
several years, but I am not always paying attention and do not save the
logs.)
Kind regards,
Paul
[1]:
https://lore.kernel.org/linux-pci/8579bd14-e369-1141-917b-204d20cff...@molgen.mpg.de/
