cxl: Fix driver use count (197267d0) · Commits · 戴 / test

cxl keeps a driver use count, which is used with the hash memory model on p8 to know when to upgrade local TLBIs to global and to trigger callbacks to manage the MMU for PSL8. If a process opens a context and closes without attaching or fails the attachment, the driver use count is never decremented. As a consequence, TLB invalidations remain global, even if there are no active cxl contexts. We should increment the driver use count when the process is attaching to the cxl adapter, and not on open. It's not needed before the adapter starts using the context and the use count is decremented on the detach path, so it makes more sense. It affects only the user api. The kernel api is already doing The Right Thing. Signed-off-by:

Frederic Barrat <fbarrat@linux.vnet.ibm.com> Cc: stable@vger.kernel.org # v4.2+ Fixes: ("cxl: Rework context lifetimes") Acked-by:

Andrew Donnellan <andrew.donnellan@au1.ibm.com> Signed-off-by:

Michael Ellerman <mpe@ellerman.id.au>

drivers/misc/cxl/api.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -336,6 +336,10 @@ int cxl_start_context(struct cxl_context *ctx, u64 wed,
		mmput(ctx->mm);
		}

		/*
		* Increment driver use count. Enables global TLBIs for hash
		* and callbacks to handle the segment table
		*/
		cxl_ctx_get();

		if ((rc = cxl_ops->attach_process(ctx, kernel, wed, 0))) {

drivers/misc/cxl/file.c

+7 −1

Original line number	Diff line number	Diff line
		@@ -95,7 +95,6 @@ static int __afu_open(struct inode inode, struct file file, bool master)

		pr_devel("afu_open pe: %i\n", ctx->pe);
		file->private_data = ctx;
		cxl_ctx_get();

		/* indicate success */
		rc = 0;
		@@ -225,6 +224,12 @@ static long afu_ioctl_start_work(struct cxl_context *ctx,
		if (ctx->mm)
		mmput(ctx->mm);

		/*
		* Increment driver use count. Enables global TLBIs for hash
		* and callbacks to handle the segment table
		*/
		cxl_ctx_get();

		trace_cxl_attach(ctx, work.work_element_descriptor, work.num_interrupts, amr);

		if ((rc = cxl_ops->attach_process(ctx, false, work.work_element_descriptor,
		@@ -233,6 +238,7 @@ static long afu_ioctl_start_work(struct cxl_context *ctx,
		cxl_adapter_context_put(ctx->afu->adapter);
		put_pid(ctx->pid);
		ctx->pid = NULL;
		cxl_ctx_put();
		cxl_context_mm_count_put(ctx);
		goto out;
		}

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