| Message ID | 20200617003835.48831-1-aik@ozlabs.ru (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 5f202c1a1d429bee3ddab647711f181c72d157da |
| Headers | show |
| Series | [kernel,v2] powerpc/powernv/ioda: Return correct error if TCE level allocation failed | expand |
| Context | Check | Description |
|---|---|---|
| snowpatch_ozlabs/apply_patch | success | Successfully applied on branch powerpc/merge (c3405d517d606e965030026daec198d314f20195) |
| snowpatch_ozlabs/build-ppc64le | success | Build succeeded |
| snowpatch_ozlabs/build-ppc64be | success | Build succeeded |
| snowpatch_ozlabs/build-ppc64e | success | Build succeeded |
| snowpatch_ozlabs/build-pmac32 | success | Build succeeded |
| snowpatch_ozlabs/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 8 lines checked |
| snowpatch_ozlabs/needsstable | success | Test needsstable on branch powerpc/merge |
On Wed, 17 Jun 2020 10:38:35 +1000, Alexey Kardashevskiy wrote: > The iommu_table_ops::xchg_no_kill() callback updates TCE. It is quite > possible that not entire table is allocated if it is huge and multilevel > so xchg may also allocate subtables. If failed, it returns H_HARDWARE > for failed allocation and H_TOO_HARD if it needs it but cannot do because > the alloc parameter is "false" (set when called with MMU=off to force > retry with MMU=on). > > [...] Applied to powerpc/next. [1/1] powerpc/powernv/ioda: Return correct error if TCE level allocation failed https://git.kernel.org/powerpc/c/5f202c1a1d429bee3ddab647711f181c72d157da cheers
diff --git a/arch/powerpc/platforms/powernv/pci-ioda-tce.c b/arch/powerpc/platforms/powernv/pci-ioda-tce.c index f923359d8afc..5218f5da2737 100644 --- a/arch/powerpc/platforms/powernv/pci-ioda-tce.c +++ b/arch/powerpc/platforms/powernv/pci-ioda-tce.c @@ -166,7 +166,7 @@ int pnv_tce_xchg(struct iommu_table *tbl, long index, if (!ptce) { ptce = pnv_tce(tbl, false, idx, alloc); if (!ptce) - return alloc ? H_HARDWARE : H_TOO_HARD; + return -ENOMEM; } if (newtce & TCE_PCI_WRITE)
The iommu_table_ops::xchg_no_kill() callback updates TCE. It is quite possible that not entire table is allocated if it is huge and multilevel so xchg may also allocate subtables. If failed, it returns H_HARDWARE for failed allocation and H_TOO_HARD if it needs it but cannot do because the alloc parameter is "false" (set when called with MMU=off to force retry with MMU=on). The problem is that having separate errors only matters in real mode (MMU=off) but the only caller with alloc="false" does not check the exact error code and simply returns H_TOO_HARD; and for every other mode alloc is "true". Also, the function is also called from the ioctl() handler of the VFIO SPAPR TCE IOMMU subdriver which does not expect hypervisor error codes (H_xxx) and will expose them to the userspace. This converts wrong error codes to -ENOMEM. Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> --- Changes: v2: * return -ENOMEM vs. -1 --- arch/powerpc/platforms/powernv/pci-ioda-tce.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)