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ocxl: Allow contexts to be attached with a NULL mm

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If an OpenCAPI context is to be used directly by a kernel driver, there
may not be a suitable mm to use.

The patch makes the mm parameter to ocxl_context_attach optional.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
Acked-by: Andrew Donnellan <ajd@linux.ibm.com>
Acked-by: Frederic Barrat <fbarrat@linux.ibm.com>
Acked-by: Nicholas Piggin <npiggin@gmail.com>
Link: https://lore.kernel.org/r/20190620041203.12274-1-alastair@au1.ibm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Alastair D'Silva 2019-06-20 14:12:01 +10:00 committed by Greg Kroah-Hartman
parent 7ce98fb6c5
commit 60e8523e2e
3 changed files with 35 additions and 7 deletions
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5
arch/powerpc/mm/book3s64/radix_tlb.c
View File

@ -666,6 +666,11 @@ EXPORT_SYMBOL(radix__flush_tlb_page);
#define radix__flush_all_mm radix__local_flush_all_mm
#endif /* CONFIG_SMP */
/*
* If kernel TLBIs ever become local rather than global, then
* drivers/misc/ocxl/link.c:ocxl_link_add_pe will need some work, as it
* assumes kernel TLBIs are global.
*/
void radix__flush_tlb_kernel_range(unsigned long start, unsigned long end)
{
_tlbie_pid(0, RIC_FLUSH_ALL);

9
drivers/misc/ocxl/context.c
View File

@ -69,6 +69,7 @@ static void xsl_fault_error(void *data, u64 addr, u64 dsisr)
int ocxl_context_attach(struct ocxl_context *ctx, u64 amr, struct mm_struct *mm)
{
int rc;
unsigned long pidr = 0;
// Locks both status & tidr
mutex_lock(&ctx->status_mutex);
@ -77,9 +78,11 @@ int ocxl_context_attach(struct ocxl_context *ctx, u64 amr, struct mm_struct *mm)
goto out;
}
rc = ocxl_link_add_pe(ctx->afu->fn->link, ctx->pasid,
mm->context.id, ctx->tidr, amr, mm,
xsl_fault_error, ctx);
if (mm)
pidr = mm->context.id;
rc = ocxl_link_add_pe(ctx->afu->fn->link, ctx->pasid, pidr, ctx->tidr,
amr, mm, xsl_fault_error, ctx);
if (rc)
goto out;

28
drivers/misc/ocxl/link.c
View File

@ -224,6 +224,17 @@ static irqreturn_t xsl_fault_handler(int irq, void *data)
ack_irq(spa, ADDRESS_ERROR);
return IRQ_HANDLED;
}
if (!pe_data->mm) {
/*
* translation fault from a kernel context - an OpenCAPI
* device tried to access a bad kernel address
*/
rcu_read_unlock();
pr_warn("Unresolved OpenCAPI xsl fault in kernel context\n");
ack_irq(spa, ADDRESS_ERROR);
return IRQ_HANDLED;
}
WARN_ON(pe_data->mm->context.id != pid);
if (mmget_not_zero(pe_data->mm)) {
@ -523,7 +534,13 @@ int ocxl_link_add_pe(void *link_handle, int pasid, u32 pidr, u32 tidr,
pe->amr = cpu_to_be64(amr);
pe->software_state = cpu_to_be32(SPA_PE_VALID);
mm_context_add_copro(mm);
/*
* For user contexts, register a copro so that TLBIs are seen
* by the nest MMU. If we have a kernel context, TLBIs are
* already global.
*/
if (mm)
mm_context_add_copro(mm);
/*
* Barrier is to make sure PE is visible in the SPA before it
* is used by the device. It also helps with the global TLBI
@ -546,7 +563,8 @@ int ocxl_link_add_pe(void *link_handle, int pasid, u32 pidr, u32 tidr,
* have a reference on mm_users. Incrementing mm_count solves
* the problem.
*/
mmgrab(mm);
if (mm)
mmgrab(mm);
trace_ocxl_context_add(current->pid, spa->spa_mem, pasid, pidr, tidr);
unlock:
mutex_unlock(&spa->spa_lock);
@ -652,8 +670,10 @@ int ocxl_link_remove_pe(void *link_handle, int pasid)
if (!pe_data) {
WARN(1, "Couldn't find pe data when removing PE\n");
} else {
mm_context_remove_copro(pe_data->mm);
mmdrop(pe_data->mm);
if (pe_data->mm) {
mm_context_remove_copro(pe_data->mm);
mmdrop(pe_data->mm);
}
kfree_rcu(pe_data, rcu);
}
unlock: