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Commit f81face7 authored by Uma Krishnan's avatar Uma Krishnan Committed by Martin K. Petersen
Browse files

scsi: cxlflash: Introduce OCXL context state machine 



In order to protect the OCXL hardware contexts from getting clobbered, a
simple state machine is added to indicate when a context is in open, close or
start state. The expected states are validated throughout the code to prevent
illegal operations on a context. A mutex is added to protect writes to the
context state field.

Signed-off-by: default avatarUma Krishnan <ukrishn@linux.vnet.ibm.com>
Acked-by: default avatarMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent d91dd3a7

drivers/scsi/cxlflash/ocxl_hw.c

+56 −3
Original line number Diff line number Diff line
@@ -163,6 +163,16 @@ static struct file *ocxlflash_getfile(struct device *dev, const char *name, 
static void __iomem *ocxlflash_psa_map(void *ctx_cookie)

{

	struct ocxlflash_context *ctx = ctx_cookie;

	struct device *dev = ctx->hw_afu->dev;



	mutex_lock(&ctx->state_mutex);

	if (ctx->state != STARTED) {

		dev_err(dev, "%s: Context not started, state=%d\n", __func__,

			ctx->state);

		mutex_unlock(&ctx->state_mutex);

		return NULL;

	}

	mutex_unlock(&ctx->state_mutex);



	return ioremap(ctx->psn_phys, ctx->psn_size);

}
@@ -343,6 +353,14 @@ static int start_context(struct ocxlflash_context *ctx) 
	int rc = 0;

	u32 pid;



	mutex_lock(&ctx->state_mutex);

	if (ctx->state != OPENED) {

		dev_err(dev, "%s: Context state invalid, state=%d\n",

			__func__, ctx->state);

		rc = -EINVAL;

		goto out;

	}



	if (master) {

		ctx->psn_size = acfg->global_mmio_size;

		ctx->psn_phys = afu->gmmio_phys;
@@ -366,7 +384,10 @@ static int start_context(struct ocxlflash_context *ctx) 
			__func__, rc);

		goto out;

	}



	ctx->state = STARTED;

out:

	mutex_unlock(&ctx->state_mutex);

	return rc;

}
@@ -396,7 +417,15 @@ static int ocxlflash_stop_context(void *ctx_cookie) 
	struct ocxl_afu_config *acfg = &afu->acfg;

	struct pci_dev *pdev = afu->pdev;

	struct device *dev = afu->dev;

	int rc;

	enum ocxlflash_ctx_state state;

	int rc = 0;



	mutex_lock(&ctx->state_mutex);

	state = ctx->state;

	ctx->state = CLOSED;

	mutex_unlock(&ctx->state_mutex);

	if (state != STARTED)

		goto out;



	rc = ocxl_config_terminate_pasid(pdev, acfg->dvsec_afu_control_pos,

					 ctx->pe);
@@ -474,7 +503,9 @@ static void *ocxlflash_dev_context_init(struct pci_dev *pdev, void *afu_cookie) 


	spin_lock_init(&ctx->slock);

	init_waitqueue_head(&ctx->wq);

	mutex_init(&ctx->state_mutex);



	ctx->state = OPENED;

	ctx->pe = rc;

	ctx->master = false;

	ctx->mapping = NULL;
@@ -499,11 +530,23 @@ static void *ocxlflash_dev_context_init(struct pci_dev *pdev, void *afu_cookie) 
static int ocxlflash_release_context(void *ctx_cookie)

{

	struct ocxlflash_context *ctx = ctx_cookie;

	struct device *dev;

	int rc = 0;



	if (!ctx)

		goto out;



	dev = ctx->hw_afu->dev;

	mutex_lock(&ctx->state_mutex);

	if (ctx->state >= STARTED) {

		dev_err(dev, "%s: Context in use, state=%d\n", __func__,

			ctx->state);

		mutex_unlock(&ctx->state_mutex);

		rc = -EBUSY;

		goto out;

	}

	mutex_unlock(&ctx->state_mutex);



	idr_remove(&ctx->hw_afu->idr, ctx->pe);

	ocxlflash_release_mapping(ctx);

	kfree(ctx);
@@ -947,7 +990,7 @@ static unsigned int afu_poll(struct file *file, struct poll_table_struct *poll) 
	spin_lock_irqsave(&ctx->slock, lock_flags);

	if (ctx_event_pending(ctx))

		mask |= POLLIN | POLLRDNORM;

	else

	else if (ctx->state == CLOSED)

		mask |= POLLERR;

	spin_unlock_irqrestore(&ctx->slock, lock_flags);
@@ -990,7 +1033,7 @@ static ssize_t afu_read(struct file *file, char __user *buf, size_t count, 
	for (;;) {

		prepare_to_wait(&ctx->wq, &event_wait, TASK_INTERRUPTIBLE);



		if (ctx_event_pending(ctx))

		if (ctx_event_pending(ctx) || (ctx->state == CLOSED))

			break;



		if (file->f_flags & O_NONBLOCK) {
@@ -1076,12 +1119,22 @@ static int ocxlflash_mmap_fault(struct vm_fault *vmf) 
{

	struct vm_area_struct *vma = vmf->vma;

	struct ocxlflash_context *ctx = vma->vm_file->private_data;

	struct device *dev = ctx->hw_afu->dev;

	u64 mmio_area, offset;



	offset = vmf->pgoff << PAGE_SHIFT;

	if (offset >= ctx->psn_size)

		return VM_FAULT_SIGBUS;



	mutex_lock(&ctx->state_mutex);

	if (ctx->state != STARTED) {

		dev_err(dev, "%s: Context not started, state=%d\n",

			__func__, ctx->state);

		mutex_unlock(&ctx->state_mutex);

		return VM_FAULT_SIGBUS;

	}

	mutex_unlock(&ctx->state_mutex);



	mmio_area = ctx->psn_phys;

	mmio_area += offset;

drivers/scsi/cxlflash/ocxl_hw.h

+8 −0
Original line number Diff line number Diff line
@@ -46,6 +46,12 @@ struct ocxl_hw_afu { 
	bool is_present;		/* Function has AFUs defined */

};



enum ocxlflash_ctx_state {

	CLOSED,

	OPENED,

	STARTED

};



struct ocxlflash_context {

	struct ocxl_hw_afu *hw_afu;	/* HW AFU back pointer */

	struct address_space *mapping;	/* Mapping for pseudo filesystem */
@@ -57,6 +63,8 @@ struct ocxlflash_context { 


	spinlock_t slock;		/* Protects irq/fault/event updates */

	wait_queue_head_t wq;		/* Wait queue for poll and interrupts */

	struct mutex state_mutex;	/* Mutex to update context state */

	enum ocxlflash_ctx_state state;	/* Context state */



	struct ocxlflash_irqs *irqs;	/* Pointer to array of structures */

	int num_irqs;			/* Number of interrupts */