Re: [PATCH v3 1/4] nitro_enclaves: Merge contiguous physical memory regions

["Paraschiv, Andra-Irina" <andraprs@amazon.com>]

On 03/11/2021 15:54, Longpeng (Mike, Cloud Infrastructure Service 
Product Dept.) wrote:
> 
> Hi Andra,
> 
> Sorry for the long delay.
> 
> I've read all your suggestions in each patch, there's no objection. I'll
> send v4 later, please review when you free, thanks.

Thank you, no problem. I'll review the patch series till the end of this 
week.

Andra

> 
>> -----Original Message-----
>> From: Paraschiv, Andra-Irina [mailto:andraprs@amazon.com]
>> Sent: Friday, October 15, 2021 9:34 PM
>> To: Longpeng (Mike, Cloud Infrastructure Service Product Dept.)
>> <longpeng2@huawei.com>
>> Cc: Gonglei (Arei) <arei.gonglei@huawei.com>; gregkh@linuxfoundation.org;
>> kamal@canonical.com; pbonzini@redhat.com; sgarzare@redhat.com;
>> stefanha@redhat.com; vkuznets@redhat.com; linux-kernel@vger.kernel.org;
>> ne-devel-upstream@amazon.com; lexnv@amazon.com; alcioa@amazon.com
>> Subject: Re: [PATCH v3 1/4] nitro_enclaves: Merge contiguous physical memory
>> regions
>>
>>
>>
>> On 09/10/2021 04:32, Longpeng(Mike) wrote:
>>>
>>> From: Longpeng <longpeng2@huawei.com>
>>>
>>> There can be cases when there are more memory regions that need to be
>>> set for an enclave than the maximum supported number of memory regions
>>> per enclave. One example can be when the memory regions are backed by 2
>>> MiB hugepages (the minimum supported hugepage size).
>>>
>>> Let's merge the adjacent regions if they are physical contiguous. This
>>
>> physical contiguous => physically contiguous
>>
>>> way the final number of memory regions is less than before merging and
>>> could potentially avoid reaching maximum.
>>>
>>> Signed-off-by: Longpeng <longpeng2@huawei.com>
>>> ---
>>> Changes v2 -> v3:
>>>     - update the commit title and commit message.  [Andra]
>>>     - use 'struct range' to instead of 'struct phys_mem_region'.  [Andra, Greg
>> KH]
>>>     - add comments before the function definition.  [Andra]
>>>     - rename several variables, parameters and function.  [Andra]
>>> ---
>>>    drivers/virt/nitro_enclaves/ne_misc_dev.c | 79
>> +++++++++++++++++++++----------
>>>    1 file changed, 55 insertions(+), 24 deletions(-)
>>>
>>> diff --git a/drivers/virt/nitro_enclaves/ne_misc_dev.c
>> b/drivers/virt/nitro_enclaves/ne_misc_dev.c
>>> index e21e1e8..eea53e9 100644
>>> --- a/drivers/virt/nitro_enclaves/ne_misc_dev.c
>>> +++ b/drivers/virt/nitro_enclaves/ne_misc_dev.c
>>> @@ -26,6 +26,7 @@
>>>    #include <linux/poll.h>
>>>    #include <linux/slab.h>
>>>    #include <linux/types.h>
>>> +#include <linux/range.h>
>>
>> Please keep the alphabetical order and move this before "#include
>> <linux/slab.h>."
>>
>>>    #include <uapi/linux/vm_sockets.h>
>>>
>>>    #include "ne_misc_dev.h"
>>> @@ -126,6 +127,16 @@ struct ne_cpu_pool {
>>>    static struct ne_cpu_pool ne_cpu_pool;
>>>
>>>    /**
>>> + * struct phys_contig_mem_regions - Physical contiguous memory regions
>>
>> Physical contiguous memory regions => Contiguous physical memory regions
>>
>>> + * @num:       The number of regions that currently has.
>>> + * @region:    The array of physical memory regions.
>>> + */
>>> +struct phys_contig_mem_regions {
>>> +       unsigned long num;
>>> +       struct range region[0];
>>
>> Should use "struct range *regions" instead, to keep a similar style with
>> regard to arrays throughout the code.
>>
>> Please align the fields name (e.g. [1]) so that it's easier to
>> distinguish between fields type and name.
>>
>> Let's also prefix with "ne" the data structure naming e.g.
>> ne_phys_contig_mem_regions. So that is similar to other data structures
>> defined in the NE kernel driver codebase.
>>
>> [1]
>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/dri
>> vers/virt/nitro_enclaves/ne_misc_dev.c#n118
>>
>>> +};
>>> +
>>> +/**
>>>     * ne_check_enclaves_created() - Verify if at least one enclave has been
>> created.
>>>     * @void:      No parameters provided.
>>>     *
>>> @@ -825,6 +836,33 @@ static int ne_sanity_check_user_mem_region_page(struct
>> ne_enclave *ne_enclave,
>>>    }
>>>
>>>    /**
>>> + * ne_merge_phys_contig_memory_regions() - Add a memory region and merge the
>> adjacent
>>> + *                                         regions if they are physical
>> contiguous.
>>
>> physical contiguous => physically contiguous
>>
>>> + * @regions   : Private data associated with the physical contiguous memory
>> regions.
>>
>> physical contiguous memory regions => contiguous physical memory regions
>>
>> @regions => @phys_contig_regions
>>
>>> + * @page_paddr: Physical start address of the region to be added.
>>> + * @page_size : Length of the region to be added.
>>> + *
>>> + * Return:
>>> + * * No return value.
>>
>> Please add "Context: Process context. This function is called with the
>> ne_enclave mutex held." before "Return", similar to other defined functions.
>>
>> Can remove these lines, as for now there is no return value:
>>
>> * Return:
>> * * No return value.
>>
>> And then can add this in the second patch in the series:
>>
>> * Context: Process context. This function is called with the ne_enclave
>> mutex held. (note: already available in the first patch)
>> * Return: (note: added in the second patch)
>> * * 0 ...
>>
>>> + */
>>> +static void
>>> +ne_merge_phys_contig_memory_regions(struct phys_contig_mem_regions
>> *regions,
>>> +                                   u64 page_paddr, u64 page_size)
>>
>> phys_contig_mem_regions => ne_phys_contig_mem_regions
>> *regions => *phys_contig_regions
>>
>> Can define something like this:
>>
>> unsigned long num = phys_contig_regions->num;
>>
>> and then use it inside the function, except the last line that
>> increments the num.
>>
>>> +{
>>> +       /* Physical contiguous, just merge */
>>
>> Physical contiguous => Physically contiguous
>>
>>> +       if (regions->num &&
>>> +           (regions->region[regions->num - 1].end + 1) == page_paddr) {
>>
>> e.g. phys_contig_regions->regions[num - 1]
>>
>>> +               regions->region[regions->num - 1].end += page_size;
>>> +
>>> +               return;
>>> +       }
>>> +
>>> +       regions->region[regions->num].start = page_paddr;
>>> +       regions->region[regions->num].end = page_paddr + page_size - 1;
>>> +       regions->num++;
>>> +}
>>> +
>>> +/**
>>>     * ne_set_user_memory_region_ioctl() - Add user space memory region to the
>> slot
>>>     *                                    associated with the current enclave.
>>>     * @ne_enclave :       Private data associated with the current enclave.
>>> @@ -843,9 +881,9 @@ static int ne_set_user_memory_region_ioctl(struct
>> ne_enclave *ne_enclave,
>>>           unsigned long max_nr_pages = 0;
>>>           unsigned long memory_size = 0;
>>>           struct ne_mem_region *ne_mem_region = NULL;
>>> -       unsigned long nr_phys_contig_mem_regions = 0;
>>>           struct pci_dev *pdev = ne_devs.ne_pci_dev->pdev;
>>> -       struct page **phys_contig_mem_regions = NULL;
>>> +       struct phys_contig_mem_regions *phys_contig_mem_regions = NULL;
>>
>> struct phys_contig_mem_regions *phys_contig_mem_regions = NULL; =>
>> struct ne_phys_contig_mem_regions phys_contig_mem_regions = {};
>>
>>> +       size_t size_to_alloc = 0;
>>>           int rc = -EINVAL;
>>>
>>>           rc = ne_sanity_check_user_mem_region(ne_enclave, mem_region);
>>> @@ -866,8 +904,9 @@ static int ne_set_user_memory_region_ioctl(struct
>> ne_enclave *ne_enclave,
>>>                   goto free_mem_region;
>>>           }
>>>
>>> -       phys_contig_mem_regions = kcalloc(max_nr_pages,
>> sizeof(*phys_contig_mem_regions),
>>> -                                         GFP_KERNEL);
>>> +       size_to_alloc = sizeof(*phys_contig_mem_regions) +
>>> +                       max_nr_pages * sizeof(struct range);
>>> +       phys_contig_mem_regions = kzalloc(size_to_alloc, GFP_KERNEL);
>>
>> Then can alloc memory for the regions field.
>>
>> phys_contig_mem_regions.regions = kcalloc(max_nr_pages,
>> sizeof(*phys_contig_mem_regions.regions), GFP_KERNEL);
>>
>> The "size_of_alloc" will not be needed in this case.
>>
>>>           if (!phys_contig_mem_regions) {
>>>                   rc = -ENOMEM;
>>>
>>> @@ -901,26 +940,16 @@ static int ne_set_user_memory_region_ioctl(struct
>> ne_enclave *ne_enclave,
>>>                   if (rc < 0)
>>>                           goto put_pages;
>>>
>>> -               /*
>>> -                * TODO: Update once handled non-contiguous memory regions
>>> -                * received from user space or contiguous physical memory regions
>>> -                * larger than 2 MiB e.g. 8 MiB.
>>> -                */
>>> -               phys_contig_mem_regions[i] = ne_mem_region->pages[i];
>>> +
>> ne_merge_phys_contig_memory_regions(phys_contig_mem_regions,
>>
>> And can pass it here like this: &phys_contig_mem_regions.
>>
>>> +
>> page_to_phys(ne_mem_region->pages[i]),
>>> +
>> page_size(ne_mem_region->pages[i]));
>>>
>>>                   memory_size += page_size(ne_mem_region->pages[i]);
>>>
>>>                   ne_mem_region->nr_pages++;
>>>           } while (memory_size < mem_region.memory_size);
>>>
>>> -       /*
>>> -        * TODO: Update once handled non-contiguous memory regions received
>>> -        * from user space or contiguous physical memory regions larger than
>>> -        * 2 MiB e.g. 8 MiB.
>>> -        */
>>> -       nr_phys_contig_mem_regions = ne_mem_region->nr_pages;
>>> -
>>> -       if ((ne_enclave->nr_mem_regions + nr_phys_contig_mem_regions) >
>>> +       if ((ne_enclave->nr_mem_regions + phys_contig_mem_regions->num) >
>>>               ne_enclave->max_mem_regions) {
>>>                   dev_err_ratelimited(ne_misc_dev.this_device,
>>>                                       "Reached max memory regions %lld\n",
>>> @@ -931,9 +960,10 @@ static int ne_set_user_memory_region_ioctl(struct
>> ne_enclave *ne_enclave,
>>>                   goto put_pages;
>>>           }
>>>
>>> -       for (i = 0; i < nr_phys_contig_mem_regions; i++) {
>>> -               u64 phys_region_addr =
>> page_to_phys(phys_contig_mem_regions[i]);
>>> -               u64 phys_region_size = page_size(phys_contig_mem_regions[i]);
>>> +       for (i = 0; i < phys_contig_mem_regions->num; i++) {
>>> +               struct range *range = phys_contig_mem_regions->region + i;
>>> +               u64 phys_region_addr = range->start;
>>> +               u64 phys_region_size = range_len(range);
>>
>> With the updated data structure field, could be:
>>
>> u64 phys_region_addr = phys_contig_mem_regions.regions[i].start;
>> u64 phys_region_size = range_len(&phys_contig_mem_regions.regions[i]);
>>
>>>
>>>                   if (phys_region_size & (NE_MIN_MEM_REGION_SIZE - 1)) {
>>>                           dev_err_ratelimited(ne_misc_dev.this_device,
>>> @@ -959,13 +989,14 @@ static int ne_set_user_memory_region_ioctl(struct
>> ne_enclave *ne_enclave,
>>>
>>>           list_add(&ne_mem_region->mem_region_list_entry,
>> &ne_enclave->mem_regions_list);
>>>
>>> -       for (i = 0; i < nr_phys_contig_mem_regions; i++) {
>>> +       for (i = 0; i < phys_contig_mem_regions->num; i++) {
>>>                   struct ne_pci_dev_cmd_reply cmd_reply = {};
>>>                   struct slot_add_mem_req slot_add_mem_req = {};
>>> +               struct range *range = phys_contig_mem_regions->region + i;
>>>
>>>                   slot_add_mem_req.slot_uid = ne_enclave->slot_uid;
>>> -               slot_add_mem_req.paddr =
>> page_to_phys(phys_contig_mem_regions[i]);
>>> -               slot_add_mem_req.size =
>> page_size(phys_contig_mem_regions[i]);
>>> +               slot_add_mem_req.paddr = range->start;
>>> +               slot_add_mem_req.size = range_len(range);
>>
>> Similarly here:
>>
>> slot_add_mem_req.paddr = phys_contig_mem_regions.regions[i].start;
>> slot_add_mem_req.size = range_len(&phys_contig_mem_regions.regions[i]);
>>
>> Then remain the kfree paths for "phys_contig_mem_regions.regions"
>> instead of "phys_contig_mem_regions".
>>
>> Thanks,
>> Andra
>>
>>>
>>>                   rc = ne_do_request(pdev, SLOT_ADD_MEM,
>>>                                      &slot_add_mem_req,
>> sizeof(slot_add_mem_req),
>>> --
>>> 1.8.3.1
>>>
>>
>>
>>
>> Amazon Development Center (Romania) S.R.L. registered office: 27A Sf. Lazar
>> Street, UBC5, floor 2, Iasi, Iasi County, 700045, Romania. Registered in Romania.
>> Registration number J22/2621/2005.



Amazon Development Center (Romania) S.R.L. registered office: 27A Sf. Lazar Street, UBC5, floor 2, Iasi, Iasi County, 700045, Romania. Registered in Romania. Registration number J22/2621/2005.