| Message ID | 20181015092416.47380-4-aik@ozlabs.ru |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | vfio/spapr_tce: Reworks for NVIDIA V100 + P9 passthrough (part 1) | expand |
On Mon, Oct 15, 2018 at 08:24:15PM +1100, Alexey Kardashevskiy wrote: > Since we are going to have 2 different preregistering helpers, let's > make it clear that mm_iommu_new() is only for the normal (i.e. not device) > memory and for existing areas mm_iommu_get() should be used instead. > > Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> I think the idea is sensible. However (and, yes, this is really an existing bug) - shouldn't we check for a request to add anything overlapping with an existing region, not just one that exactly matches? > --- > arch/powerpc/mm/mmu_context_iommu.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/arch/powerpc/mm/mmu_context_iommu.c b/arch/powerpc/mm/mmu_context_iommu.c > index a8c4a3c..839dbce 100644 > --- a/arch/powerpc/mm/mmu_context_iommu.c > +++ b/arch/powerpc/mm/mmu_context_iommu.c > @@ -141,8 +141,7 @@ long mm_iommu_new(struct mm_struct *mm, unsigned long ua, unsigned long entries, > list_for_each_entry_rcu(mem, &mm->context.iommu_group_mem_list, > next) { > if ((mem->ua == ua) && (mem->entries == entries)) { > - ++mem->used; > - *pmem = mem; > + ret = -EBUSY; > goto unlock_exit; > } >
On 17/10/2018 12:00, David Gibson wrote: > On Mon, Oct 15, 2018 at 08:24:15PM +1100, Alexey Kardashevskiy wrote: >> Since we are going to have 2 different preregistering helpers, let's >> make it clear that mm_iommu_new() is only for the normal (i.e. not device) >> memory and for existing areas mm_iommu_get() should be used instead. >> >> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> > > I think the idea is sensible. However (and, yes, this is really an > existing bug) - shouldn't we check for a request to add anything > overlapping with an existing region, not just one that exactly > matches? The overlap check is below the changed hunk: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/powerpc/mm/mmu_context_iommu.c#n150 > >> --- >> arch/powerpc/mm/mmu_context_iommu.c | 3 +-- >> 1 file changed, 1 insertion(+), 2 deletions(-) >> >> diff --git a/arch/powerpc/mm/mmu_context_iommu.c b/arch/powerpc/mm/mmu_context_iommu.c >> index a8c4a3c..839dbce 100644 >> --- a/arch/powerpc/mm/mmu_context_iommu.c >> +++ b/arch/powerpc/mm/mmu_context_iommu.c >> @@ -141,8 +141,7 @@ long mm_iommu_new(struct mm_struct *mm, unsigned long ua, unsigned long entries, >> list_for_each_entry_rcu(mem, &mm->context.iommu_group_mem_list, >> next) { >> if ((mem->ua == ua) && (mem->entries == entries)) { >> - ++mem->used; >> - *pmem = mem; >> + ret = -EBUSY; >> goto unlock_exit; >> } >> >
On Wed, Oct 17, 2018 at 02:34:32PM +1100, Alexey Kardashevskiy wrote: > > > On 17/10/2018 12:00, David Gibson wrote: > > On Mon, Oct 15, 2018 at 08:24:15PM +1100, Alexey Kardashevskiy wrote: > >> Since we are going to have 2 different preregistering helpers, let's > >> make it clear that mm_iommu_new() is only for the normal (i.e. not device) > >> memory and for existing areas mm_iommu_get() should be used instead. > >> > >> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> > > > > I think the idea is sensible. However (and, yes, this is really an > > existing bug) - shouldn't we check for a request to add anything > > overlapping with an existing region, not just one that exactly > > matches? > > The overlap check is below the changed hunk: > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/powerpc/mm/mmu_context_iommu.c#n150 Ah, right. In that case can't you just drop this whole if. I don't see that there's any use in giving different error codes for "tried to register exactly a region you registered before" and "tried to register a region overlapping one you registered before. > > > > > >> --- > >> arch/powerpc/mm/mmu_context_iommu.c | 3 +-- > >> 1 file changed, 1 insertion(+), 2 deletions(-) > >> > >> diff --git a/arch/powerpc/mm/mmu_context_iommu.c b/arch/powerpc/mm/mmu_context_iommu.c > >> index a8c4a3c..839dbce 100644 > >> --- a/arch/powerpc/mm/mmu_context_iommu.c > >> +++ b/arch/powerpc/mm/mmu_context_iommu.c > >> @@ -141,8 +141,7 @@ long mm_iommu_new(struct mm_struct *mm, unsigned long ua, unsigned long entries, > >> list_for_each_entry_rcu(mem, &mm->context.iommu_group_mem_list, > >> next) { > >> if ((mem->ua == ua) && (mem->entries == entries)) { > >> - ++mem->used; > >> - *pmem = mem; > >> + ret = -EBUSY; > >> goto unlock_exit; > >> } > >> > > >
diff --git a/arch/powerpc/mm/mmu_context_iommu.c b/arch/powerpc/mm/mmu_context_iommu.c index a8c4a3c..839dbce 100644 --- a/arch/powerpc/mm/mmu_context_iommu.c +++ b/arch/powerpc/mm/mmu_context_iommu.c @@ -141,8 +141,7 @@ long mm_iommu_new(struct mm_struct *mm, unsigned long ua, unsigned long entries, list_for_each_entry_rcu(mem, &mm->context.iommu_group_mem_list, next) { if ((mem->ua == ua) && (mem->entries == entries)) { - ++mem->used; - *pmem = mem; + ret = -EBUSY; goto unlock_exit; }
Since we are going to have 2 different preregistering helpers, let's make it clear that mm_iommu_new() is only for the normal (i.e. not device) memory and for existing areas mm_iommu_get() should be used instead. Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> --- arch/powerpc/mm/mmu_context_iommu.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)