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Commit 60e8523e authored by Alastair D'Silva's avatar Alastair D'Silva Committed by Greg Kroah-Hartman
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ocxl: Allow contexts to be attached with a NULL mm 



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: default avatarAlastair D'Silva <alastair@d-silva.org>
Acked-by: default avatarAndrew Donnellan <ajd@linux.ibm.com>
Acked-by: default avatarFrederic Barrat <fbarrat@linux.ibm.com>
Acked-by: default avatarNicholas Piggin <npiggin@gmail.com>
Link: https://lore.kernel.org/r/20190620041203.12274-1-alastair@au1.ibm.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 7ce98fb6

arch/powerpc/mm/book3s64/radix_tlb.c

+5 −0
Original line number Diff line number Diff line
@@ -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);

drivers/misc/ocxl/context.c

+6 −3
Original line number Diff line number Diff line
@@ -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;

drivers/misc/ocxl/link.c

+24 −4
Original line number Diff line number Diff line
@@ -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)) {
@@ -523,6 +534,12 @@ 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);



	/*

	 * 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
@@ -546,6 +563,7 @@ 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.

	 */

	if (mm)

		mmgrab(mm);

	trace_ocxl_context_add(current->pid, spa->spa_mem, pasid, pidr, tidr);

unlock:
@@ -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 {

		if (pe_data->mm) {

			mm_context_remove_copro(pe_data->mm);

			mmdrop(pe_data->mm);

		}

		kfree_rcu(pe_data, rcu);

	}

unlock: