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From:   Alistair Popple <apopple@nvidia.com>
To:     <akpm@linux-foundation.org>, <Felix.Kuehling@amd.com>,
        <linux-mm@kvack.org>, <rcampbell@nvidia.com>,
        <linux-ext4@vger.kernel.org>, <linux-xfs@vger.kernel.org>,
        Alex Sierra <alex.sierra@amd.com>
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        <hch@lst.de>, <jgg@nvidia.com>, <jglisse@redhat.com>,
        <willy@infradead.org>
Subject: Re: [PATCH v4 06/10] lib: test_hmm add ioctl to get zone device type
Date:   Fri, 28 Jan 2022 15:22:06 +1100
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Reviewed-by: Alistair Popple <apopple@nvidia.com>

On Thursday, 27 January 2022 2:09:45 PM AEDT Alex Sierra wrote:
> new ioctl cmd added to query zone device type. This will be
> used once the test_hmm adds zone device coherent type.
> 
> Signed-off-by: Alex Sierra <alex.sierra@amd.com>
> ---
>  lib/test_hmm.c      | 23 +++++++++++++++++++++--
>  lib/test_hmm_uapi.h |  8 ++++++++
>  2 files changed, 29 insertions(+), 2 deletions(-)
> 
> diff --git a/lib/test_hmm.c b/lib/test_hmm.c
> index c259842f6d44..fb1fa7c6fa98 100644
> --- a/lib/test_hmm.c
> +++ b/lib/test_hmm.c
> @@ -84,6 +84,7 @@ struct dmirror_chunk {
>  struct dmirror_device {
>  	struct cdev		cdevice;
>  	struct hmm_devmem	*devmem;
> +	unsigned int            zone_device_type;
>  
>  	unsigned int		devmem_capacity;
>  	unsigned int		devmem_count;
> @@ -1025,6 +1026,15 @@ static int dmirror_snapshot(struct dmirror *dmirror,
>  	return ret;
>  }
>  
> +static int dmirror_get_device_type(struct dmirror *dmirror,
> +			    struct hmm_dmirror_cmd *cmd)
> +{
> +	mutex_lock(&dmirror->mutex);
> +	cmd->zone_device_type = dmirror->mdevice->zone_device_type;
> +	mutex_unlock(&dmirror->mutex);
> +
> +	return 0;
> +}
>  static long dmirror_fops_unlocked_ioctl(struct file *filp,
>  					unsigned int command,
>  					unsigned long arg)
> @@ -1075,6 +1085,9 @@ static long dmirror_fops_unlocked_ioctl(struct file *filp,
>  		ret = dmirror_snapshot(dmirror, &cmd);
>  		break;
>  
> +	case HMM_DMIRROR_GET_MEM_DEV_TYPE:
> +		ret = dmirror_get_device_type(dmirror, &cmd);
> +		break;
>  	default:
>  		return -EINVAL;
>  	}
> @@ -1235,14 +1248,20 @@ static void dmirror_device_remove(struct dmirror_device *mdevice)
>  static int __init hmm_dmirror_init(void)
>  {
>  	int ret;
> -	int id;
> +	int id = 0;
> +	int ndevices = 0;
>  
>  	ret = alloc_chrdev_region(&dmirror_dev, 0, DMIRROR_NDEVICES,
>  				  "HMM_DMIRROR");
>  	if (ret)
>  		goto err_unreg;
>  
> -	for (id = 0; id < DMIRROR_NDEVICES; id++) {
> +	memset(dmirror_devices, 0, DMIRROR_NDEVICES * sizeof(dmirror_devices[0]));
> +	dmirror_devices[ndevices++].zone_device_type =
> +				HMM_DMIRROR_MEMORY_DEVICE_PRIVATE;
> +	dmirror_devices[ndevices++].zone_device_type =
> +				HMM_DMIRROR_MEMORY_DEVICE_PRIVATE;
> +	for (id = 0; id < ndevices; id++) {
>  		ret = dmirror_device_init(dmirror_devices + id, id);
>  		if (ret)
>  			goto err_chrdev;
> diff --git a/lib/test_hmm_uapi.h b/lib/test_hmm_uapi.h
> index f14dea5dcd06..17f842f1aa02 100644
> --- a/lib/test_hmm_uapi.h
> +++ b/lib/test_hmm_uapi.h
> @@ -19,6 +19,7 @@
>   * @npages: (in) number of pages to read/write
>   * @cpages: (out) number of pages copied
>   * @faults: (out) number of device page faults seen
> + * @zone_device_type: (out) zone device memory type
>   */
>  struct hmm_dmirror_cmd {
>  	__u64		addr;
> @@ -26,6 +27,7 @@ struct hmm_dmirror_cmd {
>  	__u64		npages;
>  	__u64		cpages;
>  	__u64		faults;
> +	__u64		zone_device_type;
>  };
>  
>  /* Expose the address space of the calling process through hmm device file */
> @@ -35,6 +37,7 @@ struct hmm_dmirror_cmd {
>  #define HMM_DMIRROR_SNAPSHOT		_IOWR('H', 0x03, struct hmm_dmirror_cmd)
>  #define HMM_DMIRROR_EXCLUSIVE		_IOWR('H', 0x04, struct hmm_dmirror_cmd)
>  #define HMM_DMIRROR_CHECK_EXCLUSIVE	_IOWR('H', 0x05, struct hmm_dmirror_cmd)
> +#define HMM_DMIRROR_GET_MEM_DEV_TYPE	_IOWR('H', 0x06, struct hmm_dmirror_cmd)
>  
>  /*
>   * Values returned in hmm_dmirror_cmd.ptr for HMM_DMIRROR_SNAPSHOT.
> @@ -62,4 +65,9 @@ enum {
>  	HMM_DMIRROR_PROT_DEV_PRIVATE_REMOTE	= 0x30,
>  };
>  
> +enum {
> +	/* 0 is reserved to catch uninitialized type fields */
> +	HMM_DMIRROR_MEMORY_DEVICE_PRIVATE = 1,
> +};
> +
>  #endif /* _LIB_TEST_HMM_UAPI_H */
>