Re: [PATCH v3 07/10] lib: test_hmm add module param for zone device type

Alistair Popple
2022-01-20T08:47:47Z

Thanks for splitting the coherent devices into separate device nodes. Couple of
comments below.

On Tuesday, 11 January 2022 9:31:58 AM AEDT Alex Sierra wrote:
> In order to configure device coherent in test_hmm, two module parameters
> should be passed, which correspond to the SP start address of each
> device (2) spm_addr_dev0 & spm_addr_dev1. If no parameters are passed,
> private device type is configured.
>
> Signed-off-by: Alex Sierra <alex.sierra@amd.com>
> ---
> lib/test_hmm.c | 74 +++++++++++++++++++++++++++++++--------------
> lib/test_hmm_uapi.h | 1 +
> 2 files changed, 53 insertions(+), 22 deletions(-)
>
> diff --git a/lib/test_hmm.c b/lib/test_hmm.c
> index 97e48164d56a..9edeff52302e 100644
> --- a/lib/test_hmm.c
> +++ b/lib/test_hmm.c
> @@ -34,6 +34,16 @@
> #define DEVMEM_CHUNK_SIZE (256 * 1024 * 1024U)
> #define DEVMEM_CHUNKS_RESERVE 16
>
> +static unsigned long spm_addr_dev0;
> +module_param(spm_addr_dev0, long, 0644);
> +MODULE_PARM_DESC(spm_addr_dev0,
> + "Specify start address for SPM (special purpose memory) used for device 0. By setting this Coherent device type will be used. Make sure spm_addr_dev1 is set too");

It would be useful if you could mention the required size for this region
(ie. DEVMEM_CHUNK_SIZE).

> +
> +static unsigned long spm_addr_dev1;
> +module_param(spm_addr_dev1, long, 0644);
> +MODULE_PARM_DESC(spm_addr_dev1,
> + "Specify start address for SPM (special purpose memory) used for device 1. By setting this Coherent device type will be used. Make sure spm_addr_dev0 is set too");
> +
> static const struct dev_pagemap_ops dmirror_devmem_ops;
> static const struct mmu_interval_notifier_ops dmirror_min_ops;
> static dev_t dmirror_dev;
> @@ -452,29 +462,44 @@ static int dmirror_write(struct dmirror *dmirror, struct hmm_dmirror_cmd *cmd)
> return ret;
> }
>
> -static bool dmirror_allocate_chunk(struct dmirror_device *mdevice,
> +static int dmirror_allocate_chunk(struct dmirror_device *mdevice,
> struct page **ppage)
> {
> struct dmirror_chunk *devmem;
> - struct resource *res;
> + struct resource *res = NULL;
> unsigned long pfn;
> unsigned long pfn_first;
> unsigned long pfn_last;
> void *ptr;
> + int ret = -ENOMEM;
>
> devmem = kzalloc(sizeof(*devmem), GFP_KERNEL);
> if (!devmem)
> - return false;
> + return ret;
>
> - res = request_free_mem_region(&iomem_resource, DEVMEM_CHUNK_SIZE,
> - "hmm_dmirror");
> - if (IS_ERR(res))
> + switch (mdevice->zone_device_type) {
> + case HMM_DMIRROR_MEMORY_DEVICE_PRIVATE:
> + res = request_free_mem_region(&iomem_resource, DEVMEM_CHUNK_SIZE,
> + "hmm_dmirror");
> + if (IS_ERR_OR_NULL(res))
> + goto err_devmem;
> + devmem->pagemap.range.start = res->start;
> + devmem->pagemap.range.end = res->end;
> + devmem->pagemap.type = MEMORY_DEVICE_PRIVATE;
> + break;
> + case HMM_DMIRROR_MEMORY_DEVICE_COHERENT:
> + devmem->pagemap.range.start = (MINOR(mdevice->cdevice.dev) - 2) ?
> + spm_addr_dev0 :
> + spm_addr_dev1;
> + devmem->pagemap.range.end = devmem->pagemap.range.start +
> + DEVMEM_CHUNK_SIZE - 1;
> + devmem->pagemap.type = MEMORY_DEVICE_COHERENT;
> + break;
> + default:
> + ret = -EINVAL;
> goto err_devmem;
> + }
>
> - mdevice->zone_device_type = HMM_DMIRROR_MEMORY_DEVICE_PRIVATE;

What initialises mdevice->zone_device_type now? It looks like it needs to get
initialised in hmm_dmirror_init(), which would be easier to do in the previous
patch rather than adding it here in the first place.

> - devmem->pagemap.type = MEMORY_DEVICE_PRIVATE;
> - devmem->pagemap.range.start = res->start;
> - devmem->pagemap.range.end = res->end;
> devmem->pagemap.nr_range = 1;
> devmem->pagemap.ops = &dmirror_devmem_ops;
> devmem->pagemap.owner = mdevice;
> @@ -495,10 +520,14 @@ static bool dmirror_allocate_chunk(struct dmirror_device *mdevice,
> mdevice->devmem_capacity = new_capacity;
> mdevice->devmem_chunks = new_chunks;
> }
> -
> ptr = memremap_pages(&devmem->pagemap, numa_node_id());
> - if (IS_ERR(ptr))
> + if (IS_ERR_OR_NULL(ptr)) {
> + if (ptr)
> + ret = PTR_ERR(ptr);
> + else
> + ret = -EFAULT;
> goto err_release;
> + }
>
> devmem->mdevice = mdevice;
> pfn_first = devmem->pagemap.range.start >> PAGE_SHIFT;
> @@ -527,15 +556,17 @@ static bool dmirror_allocate_chunk(struct dmirror_device *mdevice,
> }
> spin_unlock(&mdevice->lock);
>
> - return true;
> + return 0;
>
> err_release:
> mutex_unlock(&mdevice->devmem_lock);
> - release_mem_region(devmem->pagemap.range.start, range_len(&devmem->pagemap.range));
> + if (res && devmem->pagemap.type == MEMORY_DEVICE_PRIVATE)
> + release_mem_region(devmem->pagemap.range.start,
> + range_len(&devmem->pagemap.range));
> err_devmem:
> kfree(devmem);
>
> - return false;
> + return ret;
> }
>
> static struct page *dmirror_devmem_alloc_page(struct dmirror_device *mdevice)
> @@ -560,7 +591,7 @@ static struct page *dmirror_devmem_alloc_page(struct dmirror_device *mdevice)
> spin_unlock(&mdevice->lock);
> } else {
> spin_unlock(&mdevice->lock);
> - if (!dmirror_allocate_chunk(mdevice, &dpage))
> + if (dmirror_allocate_chunk(mdevice, &dpage))
> goto error;
> }
>
> @@ -1220,10 +1251,8 @@ static int dmirror_device_init(struct dmirror_device *mdevice, int id)
> if (ret)
> return ret;
>
> - /* Build a list of free ZONE_DEVICE private struct pages */
> - dmirror_allocate_chunk(mdevice, NULL);
> -
> - return 0;
> + /* Build a list of free ZONE_DEVICE struct pages */
> + return dmirror_allocate_chunk(mdevice, NULL);
> }
>
> static void dmirror_device_remove(struct dmirror_device *mdevice)
> @@ -1236,8 +1265,9 @@ static void dmirror_device_remove(struct dmirror_device *mdevice)
> mdevice->devmem_chunks[i];
>
> memunmap_pages(&devmem->pagemap);
> - release_mem_region(devmem->pagemap.range.start,
> - range_len(&devmem->pagemap.range));
> + if (devmem->pagemap.type == MEMORY_DEVICE_PRIVATE)
> + release_mem_region(devmem->pagemap.range.start,
> + range_len(&devmem->pagemap.range));
> kfree(devmem);
> }
> kfree(mdevice->devmem_chunks);
> diff --git a/lib/test_hmm_uapi.h b/lib/test_hmm_uapi.h
> index 17f842f1aa02..625f3690d086 100644
> --- a/lib/test_hmm_uapi.h
> +++ b/lib/test_hmm_uapi.h
> @@ -68,6 +68,7 @@ enum {
> enum {
> /* 0 is reserved to catch uninitialized type fields */
> HMM_DMIRROR_MEMORY_DEVICE_PRIVATE = 1,
> + HMM_DMIRROR_MEMORY_DEVICE_COHERENT,
> };
>
> #endif /* _LIB_TEST_HMM_UAPI_H */
>