Re: [PATCH v9 2/2] x86/sgx: Add an attribute for the amount of SGX memory in a NUMA node

From: Greg Kroah-Hartman
Date: Fri Oct 29 2021 - 10:53:38 EST


On Fri, Oct 29, 2021 at 03:18:57PM +0300, Jarkko Sakkinen wrote:
> The amount of SGX memory on the system is determined by the BIOS and it
> varies wildly between systems. It can be from dozens of MB's on desktops
> or VM's, up to many GB's on servers. Just like for regular memory, it is
> sometimes useful to know the amount of usable SGX memory in the system.
>
> Add an attribute for the amount of SGX memory in bytes to each NUMA
> node. The path is /sys/devices/system/node/node[0-9]*/sgx/size.
> Calculate these values by summing up EPC section sizes for each node
> during the driver initalization.
>
> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Jarkko Sakkinen <jarkko@xxxxxxxxxx>
> ---
> v9:
> * Fix racy initialization of sysfs attributes:
> https://lore.kernel.org/linux-sgx/YXOsx8SvFJV5R7lU@xxxxxxxxx/
>
> v8:
> * Fix a bug in sgx_numa_init(): node->dev should be only set after
> sysfe_create_group(). Otherwise, sysfs_remove_group() will issue a
> warning in sgx_numa_exit(), when sgx_create_group() is unsuccessful,
> because the group does not exist.
>
> v7:
> * Shorten memory_size to size. The prefix makes the name only longer
> but does not clarify things more than "size" would.
> * Use device_attribute instead of kobj_attribute.
> * Use named attribute group instead of creating raw kobject just for
> the "sgx" subdirectory.
>
> v6:
> * Initialize node->size to zero in sgx_setup_epc_section(), when the
> node is first accessed.
>
> v5
> * A new patch based on the discussion on
> https://lore.kernel.org/linux-sgx/3a7cab4115b4f902f3509ad8652e616b91703e1d.camel@xxxxxxxxxx/T/#t
> ---
> Documentation/ABI/stable/sysfs-devices-node | 7 +++++
> arch/x86/include/asm/sgx.h | 2 ++
> arch/x86/kernel/cpu/sgx/main.c | 31 +++++++++++++++++++++
> arch/x86/kernel/cpu/sgx/sgx.h | 2 ++
> drivers/base/node.c | 16 ++++++++++-
> 5 files changed, 57 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/ABI/stable/sysfs-devices-node b/Documentation/ABI/stable/sysfs-devices-node
> index 484fc04bcc25..12dc2149e8e0 100644
> --- a/Documentation/ABI/stable/sysfs-devices-node
> +++ b/Documentation/ABI/stable/sysfs-devices-node
> @@ -176,3 +176,10 @@ Contact: Keith Busch <keith.busch@xxxxxxxxx>
> Description:
> The cache write policy: 0 for write-back, 1 for write-through,
> other or unknown.
> +
> +What: /sys/devices/system/node/nodeX/sgx/size
> +Date: October 2021
> +Contact: Jarkko Sakkinen <jarkko@xxxxxxxxxx>
> +Description:
> + Total available physical SGX memory, also known as Enclave Page
> + Cache (EPC), in bytes.
> diff --git a/arch/x86/include/asm/sgx.h b/arch/x86/include/asm/sgx.h
> index 05f3e21f01a7..43d1ccae6c62 100644
> --- a/arch/x86/include/asm/sgx.h
> +++ b/arch/x86/include/asm/sgx.h
> @@ -365,6 +365,8 @@ struct sgx_sigstruct {
> * comment!
> */
>
> +extern const struct attribute_group sgx_node_group;
> +
> #ifdef CONFIG_X86_SGX_KVM
> int sgx_virt_ecreate(struct sgx_pageinfo *pageinfo, void __user *secs,
> int *trapnr);
> diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
> index a6e313f1a82d..86d6d309ff29 100644
> --- a/arch/x86/kernel/cpu/sgx/main.c
> +++ b/arch/x86/kernel/cpu/sgx/main.c
> @@ -714,9 +714,12 @@ static bool __init sgx_page_cache_init(void)
> spin_lock_init(&sgx_numa_nodes[nid].lock);
> INIT_LIST_HEAD(&sgx_numa_nodes[nid].free_page_list);
> node_set(nid, sgx_numa_mask);
> + sgx_numa_nodes[nid].size = 0;
> }
>
> sgx_epc_sections[i].node = &sgx_numa_nodes[nid];
> + sgx_numa_nodes[nid].dev = &node_devices[nid]->dev;
> + sgx_numa_nodes[nid].size += size;
>
> sgx_nr_epc_sections++;
> }
> @@ -790,6 +793,34 @@ int sgx_set_attribute(unsigned long *allowed_attributes,
> }
> EXPORT_SYMBOL_GPL(sgx_set_attribute);
>
> +#ifdef CONFIG_NUMA
> +static ssize_t size_show(struct device *dev, struct device_attribute *attr, char *buf)
> +{
> + unsigned long size = 0;
> + int nid;
> +
> + for (nid = 0; nid < num_possible_nodes(); nid++) {
> + if (dev == sgx_numa_nodes[nid].dev) {
> + size = sgx_numa_nodes[nid].size;
> + break;
> + }
> + }
> +
> + return sysfs_emit(buf, "%lu\n", size);
> +}
> +DEVICE_ATTR_RO(size);

static?